Cornea & External Eye

A rare but severe corneal infection caused by Acanthamoeba, a free-living amoeba that infects the cornea. It is more common in contact lens wearers and causes severe pain and visual impairment.

First-in-class TRPM8 receptor agonist approved by the FDA in 2025. An eye drop that stimulates corneal cold receptors to promote basal tear secretion, representing a new neurosensory approach for dry eye.

A rare complication of corneal ectasia (e.g., keratoconus) in which rupture of Descemet's membrane allows aqueous humor to flow into the corneal stroma, causing sudden corneal edema. It occurs in 2–3% of keratoconus cases and leads to visual impairment and pain.

Acute hemorrhagic conjunctivitis (AHC) is an acute infectious conjunctivitis caused by enterovirus 70 (EV70) or a variant of coxsackievirus A24 (CA24v). Bulbar conjunctival hemorrhage is observed in 70–90% of cases, and it is also known as "Apollo disease." There is no specific antiviral treatment; symptomatic therapy is the mainstay. It resolves spontaneously within about one week.

Allergic conjunctival diseases are inflammatory conditions of the conjunctiva primarily involving type I allergic reactions, classified into four types: seasonal, perennial, vernal keratoconjunctivitis, atopic keratoconjunctivitis, and giant papillary conjunctivitis. Based on the Japanese Society of Ophthalmic Allergy's "Clinical Practice Guidelines for Allergic Conjunctival Diseases, 3rd Edition (2021)," this article outlines the definition, diagnostic criteria, and standard treatments (anti-allergic eye drops, immunosuppressive eye drops, and steroid eye drops).

A rare bilateral corneal edema occurring as a side effect of amantadine, used for Parkinson's disease and multiple sclerosis. It dose-dependently damages corneal endothelial cells, and in most cases resolves after drug discontinuation, but may become irreversible with long-term use.

Ocular surface reconstruction using amniotic membrane. Amniotic membrane, which has anti-inflammatory, anti-fibrotic, and wound-healing promoting effects, is transplanted for various corneal and conjunctival diseases using three methods: graft, cover, and stuff. It has been covered by insurance in Japan since 2014.

A collective term for congenital developmental disorders of the anterior segment structures including the cornea, iris, anterior chamber, and lens. It encompasses a diverse group of diseases such as Axenfeld-Rieger syndrome, Peters anomaly, primary congenital glaucoma, and aniridia, with developmental glaucoma due to abnormal development of the aqueous outflow pathway being a common and important complication.

A therapeutic procedure for recurrent corneal epithelial erosion. Using a 25-27G needle, the Bowman's layer and superficial stroma are punctured to promote anchoring fiber production through wound healing response and reconstruct epithelial adhesion. It shows an 85% efficacy rate for recurrences outside the pupillary zone.

A ring-shaped opacity caused by cholesterol and phospholipid deposition in the peripheral corneal stroma associated with aging. It is observed in over 70% of individuals aged 60 and older, and in nearly all individuals aged 80 and older. When similar findings appear in individuals under 40, it is called arcus juvenilis, and evaluation for familial hypercholesterolemia is recommended.

An extremely rare corneal finding first reported by Ascher in 1964. It presents as bilateral, symmetric annular opacities 7–8 mm in diameter in the mid-peripheral corneal stroma. It does not affect vision and requires no treatment. It is considered a diagnosis of exclusion.

A relatively rare surgical procedure that replaces a damaged cornea using the patient's own cornea. There are two types: ipsilateral rotational autokeratoplasty (IRA) and full-thickness bilateral autokeratoplasty. The greatest advantage is the absence of risk of allograft rejection. It is indicated for cases at high risk of rejection or when donor corneas are difficult to obtain.

An overview of the causative organisms, symptoms, diagnosis, and treatment of bacterial conjunctivitis, including age-specific characteristics and management of drug-resistant bacteria.

Explains the pathology, clinical findings by causative organism, diagnosis, and treatment of bacterial keratitis based on the Infectious Keratitis Clinical Practice Guidelines (3rd edition). Covers the Japanese standard treatment of monotherapy for mild cases and combination therapy with two drugs for severe cases, recommendations for culture and smear, Japan-specific recommendations regarding steroid use, and preparation methods for fortified antibiotics in accordance with AAO PPP.

Band keratopathy is a chronic corneal degenerative disease caused by the deposition of calcium hydroxyapatite in Bowman's layer and the epithelial basement membrane, secondary to chronic ocular inflammation or hypercalcemia. Treatment includes EDTA chelation therapy and excimer laser therapy.

An autosomal recessive chorioretinal dystrophy caused by mutations in the CYP4V2 gene. It is characterized by crystalline deposits in the retina and cornea, and progressive chorioretinal atrophy, and is frequently found in East Asians.

A chronic inflammatory disease centered on the eyelid margin. It is broadly classified into anterior blepharitis (staphylococcal and seborrheic) and posterior blepharitis (meibomian gland dysfunction, MGD), with repeated remissions and exacerbations. Warm compresses and eyelid hygiene are the mainstays of treatment, with antibiotics or steroids added as needed.

A chronic inflammatory disease of the eyelid margin that commonly occurs in children. It is accompanied by secondary conjunctivitis and keratitis, and can lead to permanent visual impairment due to corneal scarring and amblyopia. Early multidisciplinary treatment is essential for improving prognosis.

This article outlines the types, mechanisms of action, and clinical applications of blood-derived products in ophthalmology, including autologous serum eye drops, platelet-rich plasma (PRP), and plasma rich in growth factors (PRGF).

Blue cataract is a developmental cataract with autosomal dominant inheritance that produces a bluish-white opacity in the lens nucleus and cortex. It usually does not affect vision until adulthood, and cataract surgery is indicated when it progresses and causes visual impairment.

The Boston Keratoprosthesis (Boston KPro) is the most widely used artificial cornea in the world. Type 1 is used for severe corneal diseases that are difficult to treat with conventional corneal transplantation, and Type 2 is used as a last resort for visual recovery in end-stage ocular surface diseases with loss of tear film and ocular surface keratinization.

Scleral contact lenses are rigid gas-permeable lenses that cover the entire cornea in a dome-like shape and rest on the sclera. They simultaneously correct irregular astigmatism and protect the ocular surface through a fluid reservoir. BostonSight PROSE is an FDA-approved treatment model using highly customizable prosthetic devices.

Brittle cornea syndrome (BCS) is a rare autosomal recessive connective tissue disorder caused by biallelic mutations in ZNF469 or PRDM5 genes, characterized by progressive corneal thinning and fragility, leading to a significantly high risk of corneal perforation and rupture.

A specialist explains the symptoms, causes, diagnosis, and treatment of bullous keratopathy. Detailed introduction includes irreversible corneal edema due to corneal endothelial cell damage, comparison of DMEK and DSAEK, ROCK inhibitors, and cultured corneal endothelial cell injection therapy.

A disease caused by caterpillar or insect setae penetrating ocular tissues and inducing granulomatous inflammation. This article explains the classification (Cadera Type I–V), treatment, and multimodal imaging diagnosis.

Chemical injury of the conjunctiva and cornea is an ophthalmic emergency requiring immediate irrigation. Alkali agents penetrate deeply and often cause severe damage. Severity is assessed using the Kinoshida classification or Roper-Hall classification, and management is staged from conservative treatment in the acute phase to surgical ocular surface reconstruction in the cicatricial phase.

Cicatricial conjunctivitis is a group of vision-threatening diseases characterized by chronic inflammation and scarring of the conjunctiva, caused by various factors such as autoimmune diseases (ocular cicatricial pemphigoid), drug toxicity, infections, and chemical trauma. Early diagnosis and treatment according to the underlying disease determine the prognosis.

Cogan syndrome is a rare autoimmune disease characterized by non-syphilitic interstitial keratitis and vestibuloauditory symptoms. It predominantly affects young adults and presents with recurrent ocular inflammation and progressive hearing loss. Up to 80% of patients have systemic symptoms, and up to 15% have vasculitis.

This article explains the pathophysiology, diagnosis, and management of complications after radial keratotomy (RK), including diurnal fluctuation, progressive hyperopia, corneal perforation, irregular astigmatism, and infectious keratitis.

A group of eye, visual, and musculoskeletal symptoms caused by prolonged use of digital devices. The global prevalence is approximately 66%, rising to 74% after the COVID-19 pandemic. Abnormal blinking, accommodative disorders, and environmental factors are the main mechanisms, and preventive measures such as improving the work environment and the 20-20-20 rule are important.

An in vivo imaging diagnostic method that allows non-invasive observation of the cornea at the cellular level. It has a wide range of clinical applications, including detection of pathogens in corneal infections, differentiation of corneal dystrophies, and evaluation of corneal nerves. The HRT III-RCM is the current standard device, achieving lateral resolution of 1–2 μm and depth resolution of 4 μm.

Explains the causative gene SLC4A11, symptoms, diagnosis, treatment including corneal endothelial transplantation, and pathophysiology of congenital hereditary endothelial dystrophy (CHED).

Explains the decorin gene mutation, symptoms, diagnosis, treatment including penetrating keratoplasty, and pathophysiology of congenital stromal corneal dystrophy (CSCD).

A condition in which silver deposits in the conjunctiva and cornea due to chronic exposure to silver-containing compounds. Causes include occupational exposure (jewelry making, photography development, dentistry) and long-term use of silver-containing eye drops or cosmetics. The conjunctiva appears bluish-gray, and the deep corneal layers show gray-green to golden deposits.

Definition, causes (postoperative, traumatic, congenital), diagnosis (anterior segment OCT, UBM), and treatment (excision, TCA injection, sclerotherapy, marsupialization) of conjunctival inclusion cysts.

Explains the causes (surgery, trauma, inflammation, genetics), symptoms, diagnosis (slit lamp, biopsy), and treatment (steroid injection, excision, cryotherapy, radiation) of conjunctival keloid (conjunctival fibrosis).

Classification of conjunctival lymphangiectasia (diffuse, localized, hemorrhagic), etiology (congenital anomaly, trauma, inflammation), diagnosis (anterior segment OCT, pathology), and treatment (excision, cryocoagulation, anti-VEGF, high-frequency electrocautery).

Explains the etiology (MALT antigen stimulation), diagnosis (salmon-pink lesion, flow cytometry), treatment (excision, steroids, tacrolimus, radiation), and lymphoma risk of conjunctival reactive lymphoid hyperplasia (CRLH).

Explains the causative diseases of conjunctival telangiectasia (ataxia telangiectasia, hereditary hemorrhagic telangiectasia, Fabry disease, rosacea, VHL syndrome), clinical diagnosis, differential diagnosis, and treatment.

A general term for inflammation of the conjunctiva. It is broadly classified into infectious (viral, bacterial, chlamydial) and non-infectious (allergic, toxic, etc.) types, with hyperemia, discharge, and foreign body sensation as the main symptoms.

Explains the definition, symptoms, pathophysiology, diagnosis, and treatment of conjunctivochalasis. Covers the three mechanisms of tear dynamics disorders, association with MGD, and everything from eye drop therapy to surgical therapies (resection, suturing, cauterization, and HFR-ES).

A general term for corneal and conjunctival disorders caused or triggered by contact lens wear. The main mechanisms include mechanical trauma, hypoxia, inadequate lubrication, immune reactions, and microbial infection. Identifying the cause through fluorescein staining patterns is key to diagnosis.

Contact lens peripheral ulcer (CLPU) is a non-infectious immune-inflammatory corneal infiltration that occurs in the peripheral cornea associated with contact lens wear. It is based on the host response to bacterial components such as Staphylococcus aureus. This article systematically explains the differentiation from microbial keratitis, discontinuation of contact lenses, use of antibiotic eye drops, and management with low-dose steroids.

Cornea farinata is an age-related change in which fine dust-like opacities appear bilaterally in the deep corneal stroma just anterior to Descemet's membrane. It is usually asymptomatic and requires no treatment. Differentiation from Fuchs endothelial corneal dystrophy is important.

Explanation of the causes (amiodarone, Fabry disease, ROCK inhibitors, methotrexate), clinical findings, diagnosis (slit-lamp microscopy, α-gal A activity), pathophysiology (centripetal migration of limbal stem cells), and treatment of cornea verticillata.

This article explains the definition, immune privilege, epithelial/endothelial classification, rejection rates by PKP/DALK/DSAEK/DMEK, risk factors (including vaccine-related), Khodadoust line, differential diagnosis, steroid/CsA treatment, and HLA matching for corneal allograft rejection and failure.

Explains the viscoelastic properties of the cornea and their measurement methods (ORA, Corvis ST, Brillouin microscopy), as well as clinical applications for early diagnosis of keratoconus and refractive surgery.

A complication in which hemosiderin deposits in the corneal stroma after hyphema, causing a yellowish-brown corneal opacity. It tends to occur with traumatic hyphema, especially in cases with sustained elevated intraocular pressure.

A comparative explanation of the two major corneal collagen cross-linking (CXL) techniques: Epi-off (epithelium-off) and Epi-on (transepithelial). Covers the standard Dresden protocol, accelerated protocols, indications, procedures, outcomes, and complications for each method.

Detailed explanation of corneal cross-linking (CXL) indications, surgical techniques (Dresden protocol, accelerated CXL, PACK-CXL), effects, complications, and latest research. A minimally invasive procedure that halts the progression of progressive keratoconus and post-LASIK corneal ectasia.

A shallow saucer-shaped depression in the peripheral cornea caused by disruption of the tear film due to a limbal elevation. It usually resolves quickly with appropriate lubrication, but if left untreated, it can lead to perforation.

A congenital benign choristoma that commonly occurs at the corneal limbus. It frequently complicates amblyopia due to oblique astigmatism, and refractive correction and occlusion therapy are the mainstays of treatment. For cosmetic purposes, superficial keratectomy combined with lamellar keratoplasty may be performed.

A comprehensive explanation of the corneal donation process, donor eligibility criteria, the role of eye banks, tissue evaluation and preservation, and the legal framework.

An anterior corneal dystrophy characterized by abnormal thickening and deformation of the corneal epithelial basement membrane, producing characteristic patterns called map (geographic lines), dot (punctate opacities), and fingerprint (fingerprint lines). It is a major cause of recurrent corneal erosion and is also relevant to ocular surface management before cataract surgery.

An evidence-based explanation of the symptoms, causes, diagnosis, and treatment of corneal epithelial defect (simple erosion, recurrent erosion, persistent epithelial defect).

This article explains the types, diagnosis, removal techniques (foreign body needle, drill, forceps), and postoperative management of corneal foreign bodies. It covers essential knowledge for ophthalmic emergencies, from rust ring formation due to iron foreign bodies to infection risk from vegetative foreign bodies.

An intraoperative complication during cataract surgery (phacoemulsification) in which the corneal incision is thermally damaged by friction heat around the ultrasound tip. It can cause wound closure insufficiency and high astigmatism.

A benign raised fibrous lesion on the corneal surface. It can be secondary, developing after trauma or surgery, or primary, associated with conditions such as Lowe syndrome. Although rare, it can cause visual impairment.

A detailed explanation by a specialist of the causes of corneal leukoma (infections, trauma, inflammation, degenerative diseases), severity classification (nebula, macula, leukoma), diagnostic methods, treatments such as corneal transplantation and PTK, and the latest research on losartan eye drops.

A specialist explains in detail the causes of corneal neovascularization (infection, hypoxia, chemical trauma, LSCD), pathophysiology (VEGF, angiogenic privilege), treatments such as anti-VEGF therapy, FND, and MICE, and the latest research on gene therapy and nano DDS.

A surgical treatment that transfers healthy donor nerves to the cornea to restore sensation in neurotrophic keratopathy (epithelial damage due to decreased or absent corneal sensation). There are direct and indirect methods, aiming for long-term stabilization of corneal sensation and ocular surface.

A clinical finding in which corneal nerves are observed to be thick and prominent up to the central cornea. It is associated with systemic diseases such as multiple endocrine neoplasia type 2B (MEN2B) and corneal diseases such as keratoconus and Acanthamoeba keratitis. This finding can be an important clue for early detection of undiagnosed MEN2B.

Explanation of the principle, procedure, and normal values of the corneal sensitivity test (Cochet-Bonnet esthesiometer), and differential diagnosis of decreased corneal sensitivity.

A group of hereditary diseases in which abnormal proteins deposit in the corneal stroma, primarily due to TGFBI gene mutations. Includes lattice corneal dystrophy, granular corneal dystrophy, and macular corneal dystrophy.

A new surgical technique for corneal ectasia such as keratoconus, in which donor corneal tissue is inserted into the stroma to improve corneal shape. It is attracting attention as a highly biocompatible treatment option that replaces synthetic ICRS.

A non-invasive examination technique that measures and visualizes the shape of the corneal surface. Devices based on multiple principles such as Placido rings, Scheimpflug cameras, and anterior segment OCT are available, and are essential for screening keratoconus and planning refractive surgery.

This article explains the definition of corneal allograft rejection after corneal transplantation, the three types (epithelial, stromal, and endothelial), Khodadoust line, risk factors, incidence rates by PKP/DALK/DSAEK/DMEK, and standard treatment including frequent steroid eye drops, mini-pulse therapy, and systemic cyclosporine or tacrolimus.

COVID conjunctivitis is an ocular symptom associated with SARS-CoV-2 infection, presenting as follicular conjunctivitis that often resolves spontaneously. It occurs in 1–3% of COVID-19 patients and may rarely be the initial symptom.

A benign corneal degeneration in which polygonal gray-white opacities appear in the posterior stroma with aging. The appearance resembles crocodile skin, but it is asymptomatic and requires no treatment.

Infectious keratitis occurring after corneal crosslinking (CXL). The incidence is low at 0.12–0.21%, but it can lead to corneal perforation and severe visual impairment. Treatment of infectious keratitis with PACK-CXL is also discussed.

Cystinosis is a lysosomal storage disease characterized by the accumulation of cystine within cells throughout the body. Ocular manifestations include photophobia and visual impairment due to corneal cystine crystal deposition, and treatment with cysteamine eye drops is effective.

Cytomegalovirus (CMV) corneal endotheliitis is a disease in which reactivation of CMV causes inflammation of the corneal endothelial cells. It is a chronic, recurrent anterior segment infection characterized by coin-shaped keratic precipitates, corneal edema, and elevated intraocular pressure.

A partial-thickness corneal transplant that preserves the recipient's Descemet membrane and corneal endothelium, replacing only the corneal stroma with donor tissue. Compared to penetrating keratoplasty (PK), it has no endothelial rejection and higher long-term graft survival. Keratoconus is the most common indication.

Chronic blepharitis caused by excessive infestation of Demodex folliculorum and D. brevis (eyelash mites). Characterized by cylindrical dandruff at the base of the eyelashes. Treatment includes tea tree oil, ivermectin, and Lotilaner ophthalmic solution (XDEMVY®), which is approved in the United States. It is often associated with meibomian gland dysfunction, recurrent chalazion, and recurrent corneal erosion.

A condition in which the Descemet membrane detaches from the posterior surface of the corneal stroma. It most commonly occurs as a complication of intraocular surgery, especially cataract surgery, but can also result from trauma or occur spontaneously. Extensive detachment causes corneal edema and vision loss, and early intervention with descemetopexy is the standard treatment.

A corneal endothelial transplant that only grafts the Descemet membrane and endothelial cell layer. It is the latest surgical technique for Fuchs endothelial corneal dystrophy and bullous keratopathy, offering excellent visual recovery and low rejection rates.

A corneal endothelial transplant procedure in which a donor corneal endothelial graft including Descemet's membrane and posterior stroma is transplanted. It is a standard surgical technique for Fuchs endothelial corneal dystrophy and bullous keratopathy, offering less invasiveness and faster visual recovery than full-thickness corneal transplantation.

DWEK (Descemetorhexis Without Endothelial Keratoplasty) is a surgical procedure for Fuchs endothelial corneal dystrophy in which only the Descemet membrane is stripped without donor corneal transplantation. Corneal clarity is expected from migration of peripheral endothelial cells.

Doxycycline is a broad-spectrum tetracycline antibiotic. In addition to its antibacterial effects, it has MMP-inhibitory and anti-inflammatory properties and is used for many ophthalmic conditions such as meibomian gland dysfunction, ocular rosacea, blepharitis, and recurrent corneal erosion.

Explains the effects of systemic medications and eye drops on the cornea by layer (epithelium, stroma, endothelium). Covers vortex keratopathy, crack lines, causative drugs, diagnosis, and treatment of drug deposits.

Comprehensive explanation of the pathology, diagnosis, and treatment of dry eye associated with Sjögren syndrome. Includes characteristics of aqueous tear-deficient dry eye due to lymphocytic infiltration of the lacrimal gland, Japanese diagnostic criteria, and novel treatments such as muscarinic receptor agonists and PRP lacrimal gland injection.

A comprehensive explanation of the definition, causes, diagnosis, and treatment of dry eye syndrome. Covers the Japanese 2016 diagnostic criteria, the Dry Eye Clinical Practice Guidelines (Journal of the Japanese Ophthalmological Society 2019), the TFOS DEWS III treatment algorithm, TFOD/TFOT, TFOS Lifestyle, meibomian gland dysfunction, punctal plugs, and the latest treatments.

Explains the pathology, diagnosis, and treatment of conjunctivitis and ocular surface disease (DIOSD) associated with dupilumab (Dupixent). Goblet cell reduction due to IL-4/IL-13 inhibition, five pathological mechanisms, stepwise progression, and management with tacrolimus and cyclosporine eye drops.

Explains preoperative assessment methods for corneal ectasia risk in refractive surgery. Covers screening using corneal topography, tomography, and biomechanical indices, as well as risk assessment tools such as the Randleman score, PTA, and BAD-D.

A group of hereditary connective tissue disorders caused by abnormal collagen synthesis. Classified into 13 subtypes, characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. Associated with various ocular complications such as blue sclera, corneal thinning, and keratoconus.

This article explains the developmental process of the eyeball and ocular adnexa, covering from gastrulation to optic cup formation, differentiation of each tissue, the role of retinoic acid signaling, and genes involved in developmental abnormalities.

Epidemic keratoconjunctivitis (EKC): causes, symptoms, diagnosis, and treatment explained based on the Japanese Guidelines for Viral Conjunctivitis 2025 edition. A highly contagious acute conjunctivitis caused by adenovirus species D (types AdV8/37/53/54/56/64/85), covering MSI staging, diagnostic criteria, steroid/iodine treatment flow, infection control in healthcare settings, and response under the School Health and Safety Act.

Explains symptoms, causes, diagnosis, and treatment of episcleritis. Details the difference between simple and nodular types, differentiation from scleritis using the epinephrine test, association with systemic diseases, and prevention of recurrence.

A condition in which the cornea is exposed to the external environment for a prolonged period due to incomplete eyelid closure or impaired blinking, leading to dryness, epithelial damage, and infection. Lagophthalmos is the primary cause, with a prevalence of up to 34% in ICU patients.

A surgical technique involving extensive resection of the bulbar conjunctiva and application of mitomycin C to reduce conjunctival hyperemia for cosmetic purposes. It is banned in South Korea due to serious complications such as necrotizing scleritis.

Explains the role of eye banks, donor eligibility criteria, corneal harvesting and preservation, legal framework, and current status and challenges in Japan.

Explains the techniques, indications, complications, safety, and latest research on keratopigmentation and eyeball tattooing.

This article explains ocular complications of Fabry disease (cornea verticillata, Fabry cataract, vascular tortuosity), systemic symptoms, diagnosis, and enzyme replacement therapy.

Detailed explanation of the definition, background diseases, standard treatment in Japan (rebamipide eye drops, therapeutic SCL, PTK), pathophysiology, and differential diagnosis of filamentary keratitis based on the Japanese dry eye clinical practice guidelines.

This article explains the CNA1 and CNA2 classification of cornea plana, KERA gene mutations, clinical findings (corneal flattening, shallow anterior chamber, high hyperopia), differential diagnosis, and treatment (refractive correction, corneal transplantation, cataract surgery), as well as pathophysiology.

François Central Cloudy Corneal Dystrophy (CCCD) is a rare corneal dystrophy characterized by bilateral, symmetrical, polygonal gray opacities in the posterior stroma of the central cornea. It is non-progressive and usually does not affect visual function; observation is the standard management.

Explanation of the mechanism, risk factors, prevention, management, and complications of free cap during LASIK surgery.

A comprehensive explanation of Fuchs endothelial corneal dystrophy (FECD) from a Japanese perspective, covering definition, Krachmer classification, epidemiology, TCF4/COL8A2 genes, diagnosis, DMEK/DSAEK/DWEK, ROCK inhibitor eye drops, and cultured endothelial cell injection therapy.

Fuchs superficial marginal keratitis (FSMK) is a rare inflammatory disease characterized by recurrent infiltration and progressive thinning of the peripheral cornea. Formation of pseudopterygium is characteristic, and it can lead to irregular astigmatism or perforation.

Fungal keratitis (corneal mycosis) is a severe eye infection caused by fungi such as filamentous fungi and Candida species. It often progresses slowly and is resistant to treatment, potentially leading to corneal perforation and blindness.

Gelatinous drop-like corneal dystrophy (GDLD) is an autosomal recessive hereditary corneal disease caused by TACSTD2 gene mutations, leading to tight junction dysfunction and amyloid deposition beneath the corneal epithelium. It is relatively common in Japan and was designated as a specified intractable disease in 2019.

A rare chronic inflammatory disease occurring in the elderly, characterized by recurrent purulent conjunctivitis against a background of abnormally deep upper eyelid fornix. Colonization by Staphylococcus aureus is the main cause, and fornix shortening surgery is attracting attention as an effective surgical treatment.

Giant papillary conjunctivitis (GPC) is a conjunctivitis characterized by the formation of giant papillae (≥1 mm in diameter) on the upper tarsal conjunctiva due to mechanical irritation from contact lenses, ocular prostheses, surgical sutures, etc. It is classified as an independent disease type in the Japanese Guidelines for Allergic Conjunctival Diseases (3rd edition) and is most commonly seen in contact lens wearers.

An autosomal dominant corneal dystrophy caused by TGFBI gene mutations, leading to deposition of hyaline and amyloid in the corneal stroma. It is classified into type 1 (R555W) and type 2 (R124H, formerly Avellino), with type 2 being overwhelmingly more common in Japan. PTK is the first-line treatment.

An autosomal dominant disorder characterized by benign plaque formation in the conjunctiva, cornea, and oral mucosa. Also known as "red eye disease" due to prominent bilateral conjunctival injection. Onset occurs in early childhood with lifelong exacerbations and remissions. Causes include 4q35 duplication or NLRP1 gene mutations.

Hereditary transient corneal endotheliitis is an autosomal dominant disorder caused by NLRP3 gene mutations, characterized by recurrent episodes of debilitating inflammatory attacks in one eye, with pain, corneal edema, conjunctival injection, and vision loss. Attacks last 2–5 days and occur 1–8 times per year. It is common in Finnish populations but also reported in other European populations.

An overview of keratitis caused by herpes simplex virus (HSV). This article explains the pathophysiology, diagnosis, and treatment of each disease type—epithelial (dendritic keratitis), stromal (disciform and necrotizing), endothelitis, and neurotrophic keratopathy—based on the Japanese Infectious Keratitis Clinical Practice Guidelines, 3rd edition, and the classification of the Ocular Herpes Infection Study Group.

Herpes zoster caused by reactivation of varicella-zoster virus (VZV) in the first division of the trigeminal nerve, leading to various ocular complications such as keratitis, uveitis, and optic neuritis. Explained in accordance with the Japanese Infectious Keratitis Clinical Practice Guidelines, 3rd edition.

A benign corneal epitheliopathy characterized by a whorl-like fluorescein staining pattern on the corneal epithelium, occurring after full-thickness keratoplasty, hard contact lens wear, or chronic steroid eye drop use. It resolves spontaneously upon removal of the cause.

Infectious crystalline keratopathy (ICK) is a slowly progressive infectious keratitis characterized by branching crystalline opacities within the corneal stroma. Inflammatory response is minimal, and it commonly occurs under steroid use after corneal transplantation. Biofilm formation contributes to treatment resistance, and in refractory cases, intrastromal antibiotic injection or therapeutic corneal transplantation may be required.

Intense pulsed light (IPL) therapy is a treatment for meibomian gland dysfunction (MGD) and evaporative dry eye. Non-coherent polychromatic light of 500–1200 nm is applied to the periorbital area, improving tear film stability through photothermolysis of abnormal blood vessels, warming of meibum, and anti-inflammatory effects.

Interface fluid syndrome (IFS) is a complication after LASIK in which fluid accumulates at the flap interface. It is primarily caused by steroid-induced intraocular pressure elevation and is also called pressure-induced stromal keratitis (PISK). The mainstay of treatment is discontinuation of steroids and reduction of intraocular pressure.

Interstitial keratitis (IK) is a non-ulcerative inflammation of the corneal stroma that does not directly involve the epithelium or endothelium, and is characterized by stromal neovascularization and scarring. Etiologies are broadly divided into infectious (herpes simplex virus, syphilis, etc.) and immune-mediated (Cogan syndrome, etc.).

Intracorneal ring segments (ICRS) are a treatment for corneal ectasia such as keratoconus, inserted into the corneal stroma to flatten the central cornea. They improve corneal shape through an arc-shortening effect and contribute to biomechanical stabilization.

Iris trauma repair is a surgical method for treating iris dialysis, traumatic mydriasis, and pupillary deviation caused by blunt or penetrating ocular trauma. Techniques such as the modified Siepser sliding knot, McCannel method, single-pass four-throw (SFT) method, and iris cerclage are used to perform pupilloplasty, improving photophobia and optical aberrations.

A skin infection in which herpes simplex virus spreads extensively on a background of inflammatory skin diseases such as atopic dermatitis. Herpetic keratitis involving the eye is a vision-threatening complication.

Keratoconus is an ectatic corneal disorder in which the central corneal stroma progressively thins and protrudes forward into a cone shape, causing high irregular astigmatism and visual impairment. It typically begins in adolescence and progresses into the 30s. First-line treatment for progression is corneal cross-linking (CXL), and visual correction is achieved with rigid gas-permeable contact lenses or scleral lenses.

Keratoglobus is a rare non-inflammatory corneal ectasia characterized by diffuse thinning of the entire cornea and spherical forward protrusion. The congenital type is associated with Ehlers-Danlos syndrome type VI and blue sclera syndrome, while the acquired type progresses from pellucid marginal degeneration or keratoconus. Thinning is most pronounced in the periphery, and there is a risk of corneal rupture even with minor trauma.

Keratolimbal allograft (KLAL) is a type of ocular surface stem cell transplantation for limbal stem cell deficiency (LSCD). It involves transplanting allogeneic limbal tissue attached to a corneoscleral carrier from a cadaveric donor to restore corneal epithelial homeostasis. It is indicated for bilateral LSCD or cases where a living donor is unavailable, and systemic immunosuppression is essential.

This article explains the role of corneal topography and tomography in refractive surgery. It summarizes key points of corneal shape analysis in preoperative screening, ectasia risk assessment, various indices, and postoperative management.

LASIK surgery after corneal transplantation is a refractive surgery that corrects residual refractive errors and astigmatism after penetrating keratoplasty (PKP). After PKP, an average of 4–5 D of astigmatism occurs, and LASIK is considered for cases where correction with glasses or contact lenses is difficult. Attention must be paid to the risks of wound dehiscence and graft rejection.

Lattice corneal dystrophy is a hereditary corneal dystrophy in which amyloid deposits in a lattice pattern in the corneal stroma. It is broadly classified into LCD1, an autosomal dominant form caused by TGFBI gene mutations, variant types (e.g., type 3A), and gelsolin type (Meretoja syndrome). It causes recurrent epithelial erosions and progressive vision loss, and PTK and deep anterior lamellar keratoplasty (DALK) are standard treatments.

A condition in which the uppermost part of the conjunctiva of the upper eyelid (lid wiper) develops epithelial damage due to friction during blinking. It is strongly associated with dry eye symptoms in contact lens wearers.

An extremely rare conjunctivitis characterized by chronic, recurrent formation of woody-hard fibrinous pseudomembranes on the palpebral conjunctiva, associated with plasminogen deficiency. It may involve systemic mucosal lesions.

A disease in which the limbus, where corneal epithelial stem cells reside, is damaged, leading to loss of corneal epithelial regenerative capacity. Visual impairment occurs due to conjunctival epithelial invasion (conjunctivalization), superficial neovascularization, and corneal opacity.

A rare corneal disease characterized by linear opacities in the corneal stroma. The etiology is unknown, but an autoimmune involvement is suspected. It responds well to steroid eye drops, but may follow a relapsing-remitting course.

A corneal degenerative disease in which cholesterol and phospholipids deposit in the corneal stroma. It is classified into primary (rare) and secondary (associated with corneal neovascularization). Secondary cases often occur after herpetic keratitis or trauma, and treatment mainly involves occlusion of neovascular vessels.

A rare superficial corneal dystrophy caused by heterozygous loss-of-function mutations in MCOLN1 at Xp22.3. Gray, whorl-like, feathery microcysts appear in the corneal epithelium, causing painless progressive blurred vision. First described by Lisch et al. in 1992.

An ocular surface stem cell transplantation procedure in which conjunctival and limbal tissue from a living relative is transplanted for limbal stem cell deficiency (LSCD). It is indicated for bilateral LSCD or unilateral LSCD where the contralateral eye is unsuitable as a donor. Performed under systemic immunosuppression, the ocular surface stabilization rate is reported to be 45–92%.

A parasitic infection of the subcutaneous and subconjunctival tissues caused by the filarial worm Loa loa. It is transmitted by Chrysops flies and is endemic in Central and West Africa. It is characterized by subconjunctival migration of the worm and Calabar swellings. Diethylcarbamazine (DEC) is the first-line treatment.

The first FDA-approved treatment for Demodex blepharitis. It is an isoxazoline GABA receptor-gated chloride channel inhibitor that induces spastic paralysis and kills Demodex mites. Administer 0.25% ophthalmic solution twice daily for 6 weeks.

Macular corneal dystrophy (MCD) is an autosomal recessive corneal dystrophy caused by mutations in the CHST6 gene, leading to diffuse accumulation of glycosaminoglycans (keratan sulfate) in the corneal stroma. Bilateral vision loss occurs from around 10 to 30 years of age. Treatment includes deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PKP).

A comprehensive overview of the etiology, diagnosis, and treatment of descemetocele (anterior bulging of Descemet's membrane due to corneal stromal defect) and corneal perforation, ranging from conservative to surgical management.

Extrusion of intracorneal ring segments (ICRS) is a complication in which the ring protrudes due to progressive corneal stromal thinning and epithelial breakdown. It accounts for about half of all removal cases and is preceded by ring migration or corneal melting. Recovery is possible with removal surgery.

Overcorrection after LASIK can cause difficulty with near vision, eye strain, and decreased quality of vision. The Refractive Surgery Guidelines (8th edition) set a goal of avoiding postoperative overcorrection. Conservative correction is the first choice; additional interventions such as enhancement surgery, PRK, or TG-LASIK should be performed with careful indication assessment.

A recurrent inflammatory disease characterized by sterile infiltration and ulceration in the peripheral cornea due to a type III allergic reaction to antigens of staphylococci that normally reside on the eyelids. It is frequently associated with blepharitis.

An autosomal dominant corneal dystrophy characterized by multiple microcysts within the corneal epithelium due to mutations in the KRT3 or KRT12 genes. Onset occurs early in life, but symptoms are usually mild and may include recurrent corneal erosions.

A non-progressive congenital anomaly in which the horizontal corneal diameter is 13 mm or more (12 mm or more in newborns). X-linked recessive inheritance is most common, caused by a mutation in the CHRDL1 gene leading to deficiency of ventroptin, a BMP-4 antagonist. Differentiation from congenital glaucoma (buphthalmos) is important.

A chronic diffuse abnormality of the meibomian glands, characterized by terminal duct obstruction and/or qualitative or quantitative changes in glandular secretions. It is the most common cause of evaporative dry eye, affecting 10–30% of individuals aged 50 years or older in Japan.

A general term for conjunctivitis in which a membrane composed of fibrin and inflammatory exudate forms on the conjunctival surface. True membranes embed into the conjunctival epithelium and bleed upon removal, whereas pseudomembranes adhere to the surface and can be easily removed. Adenoviral conjunctivitis is the most common cause.

A group of diseases that cause structural and functional changes in the cornea due to genetic enzyme deficiencies or acquired metabolic dysregulation (e.g., diabetes). Abnormal accumulation of metabolic products impairs corneal transparency, leading to vision loss. Diabetic keratopathy is the most common clinically.

Keratitis caused by methamphetamine (stimulant) abuse. Pharmacological vasoconstriction, corneal hypoesthesia, and tear film dysfunction, combined with chemical toxicity of contaminants and behavioral factors, cause complex corneal damage. It has features of neurotrophic keratopathy and is frequently complicated by infectious keratitis.

Microsporidia are obligate intracellular spore-forming fungi that cause ocular infections presenting as two clinical forms: keratoconjunctivitis and stromal keratitis. They affect not only immunocompromised individuals but also immunocompetent individuals, and are often misdiagnosed as herpetic keratitis. Special staining of corneal scrapings and confocal microscopy are useful for diagnosis.

Cardenolides (cardiac glycosides) in the milky sap (latex) of plants in the genus Asclepias inhibit Na+/K+-ATPase in the corneal endothelium, causing corneal edema due to impaired corneal pump function. Recovery usually occurs within a few days with eye irrigation, steroid eye drops, and hypertonic agents.

Mitomycin intravascular chemoembolization (MICE) is a new treatment for corneal neovascularization and lipid keratopathy that affect visual function. Mitomycin C (MMC) is selectively injected into corneal neovessels, inducing vascular occlusion through irreversible cytotoxicity to the vascular endothelium.

Modified Osteo-Odonto-Keratoprosthesis (MOOKP) is a keratoprosthesis that uses the patient's own tooth and alveolar bone as a biological support. It is performed as a multi-stage surgery combining an oral mucosal graft and a PMMA optical cylinder, as a final visual function restoration method for bilateral end-stage ocular surface diseases.

Mooren's ulcer (rodent corneal ulcer) is an idiopathic autoimmune peripheral corneal ulcer that progresses along the corneal limbus. It is characterized by an arcuate ulcer with undermined edges, and the sclera is not involved. An autoimmune reaction against calgranulin C in the corneal stroma is thought to be involved in the pathogenesis.

Mpox (monkeypox) is a zoonotic disease caused by the monkeypox virus (MPXV), a member of the Orthopoxvirus genus. Ophthalmic complications (MPXROD) primarily affect the eyelids, conjunctiva, and cornea, and can cause ulcerative keratitis and immune stromal keratitis. Severe cases may lead to permanent vision loss due to corneal scarring.

Mucus fishing syndrome is a chronic inflammatory ocular surface disease caused by repeatedly manually removing mucus from the conjunctival fornix. The core pathology is a vicious cycle in which mechanical trauma stimulates goblet cells to increase mucus production, which in turn triggers further removal behavior.

The Mycotic Corneal Ulcer Treatment Trial (MUTT) is a large randomized controlled trial comparing the efficacy of topical natamycin and topical voriconazole for filamentous fungal keratitis. MUTT 1 showed superiority of natamycin (especially for Fusarium species), and MUTT 2 found no overall benefit from adding oral voriconazole.

Neuhauser syndrome (MMR syndrome) is a rare autosomal recessive disorder characterized by the triad of megalocornea, intellectual disability, and hypotonia. This article reviews ocular findings, genetic background, differential diagnosis, and management.

Neurotrophic keratitis (NK) is a degenerative disease in which corneal epithelial homeostasis is disrupted due to impaired corneal sensory innervation from the trigeminal nerve. This article explains stage-specific management according to the Mackie classification, treatment with cenegermin (rhNGF), and corneal nerve regeneration surgery.

Nocardia keratitis is a rare corneal infection caused by the actinomycete Nocardia, which inhabits soil. It is characterized by wreath-like infiltrates, and differentiation from fungal keratitis is important. This article explains treatment with amikacin eye drops, as well as diagnosis and management.

Immune-related adverse events in the eye and orbit caused by immune checkpoint inhibitors (ICIs) used in cancer immunotherapy. They present with various conditions such as dry eye, uveitis, orbital myositis, and retinal vasculitis.

Ocular bee injuries are eye injuries caused by stings from honeybees or hornets, which can lead to complications such as toxic keratopathy, optic neuritis, glaucoma, and cataracts. Removal of the stinger, steroid treatment, and close follow-up are important.

This article explains the symptoms, diagnosis, and treatment of ocular complications in epidermolysis bullosa (EB), including corneal erosion, ectropion, and symblepharon. It covers the relationship between the four major disease types and ocular findings.

Multiple endocrine neoplasia (MEN) is a group of rare hereditary disorders in which neoplasms develop in two or more endocrine glands. In MEN type 2B, marked thickening of corneal nerves, neuromas of the conjunctiva and eyelids, and dry eye are characteristic ocular findings. In MEN type 1, visual field defects due to pituitary tumors may occur.

Ocular graft versus host disease (oGVHD) develops after allogeneic hematopoietic stem cell transplantation and causes severe dry eye, corneal ulcers, and conjunctival scarring. This article explains the latest findings including tear biomarkers and mesenchymal stem cell therapy.

Alkaptonuria (AKU) is a rare autosomal recessive disorder caused by accumulation of homogentisic acid, presenting with characteristic bluish-black pigmentation (ochronosis) of the sclera, conjunctiva, and cornea. Treatment advances including nitisinone are discussed.

Cutaneous T-cell lymphoma (CTCL) is a non-Hodgkin lymphoma in which malignant T cells infiltrate the skin, and can cause ocular symptoms such as seborrheic blepharoconjunctivitis, cicatricial ectropion, and madarosis of the eyelids and conjunctiva.

This article explains the symptoms, diagnosis, and treatment of ocular complications associated with psoriasis (dry eye, blepharitis, uveitis, cataracts, etc.). Approximately 10% of psoriasis patients develop ocular symptoms, and immune abnormalities via the IL-23/Th17 pathway serve as a common pathological basis.

Ocular mucous membrane pemphigoid (ocular cicatricial pemphigoid, OCP) is an autoimmune disease in which autoantibodies against adhesion components of the conjunctival basement membrane cause chronic progressive scarring. Disease progression is assessed using the Foster classification stages I to IV, and early systemic immunosuppressive therapy determines visual prognosis.

Chronic pain that persists despite minimal organic findings in the cornea or ocular surface. It is classified into peripheral and central types, differentiated by proparacaine test and IVCM. Stepwise topical and systemic treatment is performed.

Ocular rosacea is the ocular form of rosacea, causing chronic blepharitis, meibomian gland dysfunction, and keratitis. It is managed with stepwise eyelid hygiene and medication, but if left untreated, it can lead to corneal scarring and perforation.

Antibody-drug conjugates (ADCs) are a new generation of anticancer drugs, but they can cause ocular surface adverse events such as microcystic epithelial changes (MECs), conjunctivitis, and limbal stem cell dysfunction. Management involves regular ophthalmic examinations and dose adjustments.

The ocular surface microbiome is a community of bacteria, fungi, and viruses that reside on the conjunctiva and cornea, involved in maintaining homeostasis and immune regulation. Dysbiosis is associated with many ocular diseases such as dry eye, keratitis, and meibomian gland dysfunction.

This article explains the indications, surgical techniques (CLAu, SLET, CLET, COMET), pathophysiology, and latest research on ocular surface reconstruction for limbal stem cell deficiency (LSCD).

A general term for dysplasia to malignant tumors arising from squamous epithelial cells of the ocular surface. It ranges from mild intraepithelial neoplasia to invasive squamous cell carcinoma, with risk factors including UV exposure, HIV, and HPV infection.

A specialized explanation of ocular complications (uveitis, scleritis, keratitis, dry eye) associated with hidradenitis suppurativa (HS), including symptoms, diagnosis, and treatment. The effectiveness of anti-TNF-α therapy and the importance of regular ophthalmologic screening are also introduced.

This article explains the symptoms, diagnosis, and treatment of ocular complications (ectropion, exposure keratopathy, MGD, fleck corneal dystrophy) associated with ichthyosis (vulgaris, X-linked, lamellar, harlequin). It introduces differences in ocular findings among types and key management points.

This article explains ocular side effects of isotretinoin (13-cis-RA) including dry eye, meibomian gland dysfunction, blepharitis, corneal abnormalities, and retinal disorders. It covers dose relationship, diagnosis, treatment, and prevention.

Mucolipidosis (ML I–IV) is a group of inherited storage disorders caused by defects in lysosomal enzyme transport or function, with varying ocular manifestations depending on the subtype. ML I is characterized by a macular cherry-red spot, while ML IV features early corneal opacities and progressive retinal dystrophy.

A benign dermal melanocytosis characterized by bluish-gray to brown pigmentation of the skin, sclera, and uvea in the distribution of the trigeminal nerve V1/V2 branches. There is a risk of glaucoma and uveal melanoma, making regular ophthalmic examinations important.

A comprehensive explanation of various staining agents used in ophthalmology, including fluorescein, lissamine green, rose bengal, trypan blue, and ICG, covering their types, principles, clinical applications, and side effects.

This article explains the mechanism of action, clinical trials, administration, and real-world clinical data of Oxervate (cenegermin-bkbj 0.002%), the first FDA-approved treatment for neurotrophic keratitis (NK).

Keratitis and keratoconjunctivitis caused by ocular exposure to palytoxin (PTX). The toxin is derived from soft corals such as Palythoa, and commonly occurs in aquarium hobbyists.

A syndrome characterized by unilateral granulomatous follicular conjunctivitis and ipsilateral regional lymphadenopathy. The most common cause is cat scratch disease (Bartonella henselae), and the prognosis is often good.

Full-thickness corneal transplantation performed in patients under 18 years of age. Main indications include congenital corneal opacities and acquired corneal diseases. However, graft failure rates are higher compared to adults, and multidisciplinary collaboration including amblyopia management is essential.

A non-inflammatory, non-hereditary corneal ectasia characterized by band-like thinning and anterior protrusion of the inferior peripheral cornea. It is considered a variant of keratoconus and causes decreased visual acuity due to high irregular astigmatism.

A transplant surgery that replaces the full thickness of the cornea with donor cornea. Main indications include bullous keratopathy, keratoconus, corneal leukoma, and corneal dystrophy. The three major complications are rejection, glaucoma, and infection. In recent years, indications have been changing due to the spread of lamellar keratoplasty.

Perfluorohexyloctane (Miebo®) is the first FDA-approved tear evaporation-targeted eye drop for treating signs and symptoms of evaporative dry eye. It is a 100% active ingredient, water-free, preservative-free formulation that forms a monolayer on the tear film surface to inhibit evaporation.

A group of diseases presenting with crescent-shaped destructive inflammation in the peripheral cornea. It is strongly associated with systemic autoimmune diseases such as rheumatoid arthritis, and can lead to corneal perforation if left untreated. Early systemic immunosuppressive therapy and multidisciplinary collaboration are important.

A surgery that corrects refractive errors by inserting an intraocular lens while preserving the natural crystalline lens. It is an alternative to LASIK for moderate to high myopia, and because the cornea is not removed, it offers excellent reversibility. It is broadly classified into anterior chamber and posterior chamber types.

Pharyngoconjunctival fever (PCF, pool fever) is an adenovirus infection characterized by the three main symptoms of fever, pharyngitis, and conjunctivitis. It commonly occurs in children and spreads during the summer. Under the School Health and Safety Act, it is classified as a Type 2 infectious disease requiring school exclusion for 2 days after the resolution of major symptoms. Diagnosis, treatment, and infection control are explained based on the Viral Conjunctivitis Clinical Practice Guidelines 2025 edition.

A disease characterized by nodular inflammation of the cornea or conjunctiva due to a type IV (delayed-type) hypersensitivity reaction to exogenous antigens. Currently, Cutibacterium acnes (formerly Propionibacterium acnes) and Staphylococcus aureus are the main causes. In Japan, it is understood as a subtype of meibomian gland-associated keratoconjunctival epitheliopathy (MRKC). In tuberculosis-endemic regions, Mycobacterium tuberculosis remains an important cause.

An acute disease in which the corneal epithelium is damaged by exposure to ultraviolet radiation. Typical examples are electric ophthalmia (welding) and snow blindness (skiing). After a latent period of several hours, severe eye pain occurs, but it usually heals spontaneously within 24 to 72 hours.

A treatment that uses an excimer laser (193 nm) to remove corneal surface opacities and irregularities. Indications include corneal dystrophy, band keratopathy, and recurrent corneal erosion. FDA approved in 1995.

A yellowish-white raised lesion on the bulbar conjunctiva in the interpalpebral fissure. Ultraviolet exposure and aging are the main causes, and it is found in most people over 50 years of age. Usually asymptomatic, but when inflamed it becomes pingueculitis, which is treated with low-concentration steroid eye drops.

A rare autosomal dominant corneal dystrophy affecting the posterior stroma and Descemet's membrane. It is characterized by bilateral sheet-like posterior stromal opacities, corneal flattening and thinning, and is usually non-progressive. Deletion of the SLRP gene cluster on chromosome 12q21.33 is involved.

A rare congenital corneal disease characterized by increased curvature of the posterior corneal surface. Usually unilateral and sporadic, accompanied by corneal stromal opacity. It has been suggested to be associated with anterior segment dysgenesis (mildest form of Peters anomaly). There are two subtypes: generalized and localized.

An autosomal dominant corneal dystrophy affecting the corneal endothelium and Descemet's membrane. It presents with vesicular changes, band-like lesions, and diffuse opacities. Four genetic loci (OVOL2, COL8A2, ZEB1, GRHL2) have been identified, and abnormal epithelial-mesenchymal transition (EMT) is central to the pathogenesis.

A rare complication in which necrotizing scleritis occurs adjacent to the surgical wound after ophthalmic surgery. Type IV hypersensitivity is considered central to the pathology, and it is often associated with autoimmune diseases. Early systemic steroid administration is associated with good visual prognosis.

This article explains the types and characteristics of preservatives essential for maintaining sterility in multi-dose eye drops, and the mechanisms, clinical features, and management of ocular surface toxicity, primarily focusing on benzalkonium chloride (BAK). It also outlines the advantages and limitations of alternative preservatives and preservative-free formulations.

A rare corneal disease in which a wave-like plaque extends from the superior limbus toward the center due to dysfunction of corneal limbal stem cells. Good prognosis is achieved with silver nitrate application.

A specialist explains the symptoms, causes, diagnosis, and treatment of Pseudomonas aeruginosa keratitis. Detailed coverage includes contact lens-related risks, characteristics of ring abscess, fluoroquinolone treatment, and pathophysiology of liquefactive necrosis.

A chronic disease in which fibrovascular tissue of the conjunctiva extends onto the cornea in a wing-like shape. Ultraviolet exposure is the greatest risk factor, and surgical excision with conjunctival autograft is the mainstay of treatment.

A surgical procedure that permanently closes the punctum and vertical canaliculus using thermal or electrocautery. It prolongs tear retention time and protects the ocular surface in severe dry eye.

A small device that closes the lacrimal drainage system to increase tear volume on the ocular surface. Widely used as an adjunct to eye drops in dry eye treatment.

A very rare hereditary corneal dystrophy characterized by punctiform and polychromatic minute opacities in the pre-Descemet layer. Asymptomatic with good visual prognosis.

A vision-threatening keratitis caused by the aquatic oomycete Pythium insidiosum. It closely resembles fungal keratitis but antifungal drugs are ineffective; early accurate diagnosis and antibacterial treatment determine the prognosis.

A condition in which epithelial erosions recur due to abnormal adhesion of the corneal epithelium. Characterized by sudden eye pain upon waking, and managed stepwise from conservative therapy to surgical treatment.

This article explains the ocular findings, diagnosis, and treatment of rhinosporidiosis, a chronic granulomatous disease caused by Rhinosporidium seeberi. It focuses on its predilection for the conjunctiva and lacrimal sac, histopathological diagnosis, and treatment with surgical excision plus electrocautery.

A honeycomb-like corneal epithelial edema that occurs with the use of ROCK inhibitors (netarsudil, ripasudil), which are glaucoma medications. It is reversible upon discontinuation of the drug.

This article explains the mechanism of action, pharmacological properties, and clinical applications of Rho kinase inhibitors (ROCK inhibitors) for corneal diseases. It focuses on the promotion of corneal endothelial regeneration after Fuchs endothelial corneal dystrophy and Descemet membrane detachment surgery, and describes the indications and safety of ripasudil and netarsudil.

A non-inflammatory corneal degeneration characterized by bluish-gray subepithelial nodules on Bowman's layer. Often secondary to chronic ocular surface disease, it can cause visual impairment and irregular astigmatism.

An autosomal dominant stromal corneal dystrophy characterized by abnormal deposition of cholesterol and phospholipids in the cornea due to UBIAD1 gene mutation. It features corneal crystals and central opacity.

A disease characterized by severe eye pain and redness due to inflammation of the sclera. It often occurs in association with systemic autoimmune diseases such as rheumatoid arthritis, and necrotizing scleritis can lead to serious visual impairment.

A rare congenital disease in which the corneal limbal primordium fails to form due to abnormal neural crest cell migration, resulting in corneal opacity resembling sclera. It is bilateral and asymmetric, often accompanied by flat cornea and anterior segment abnormalities.

Refractive surgery is an irreversible treatment that invades a normal anterior segment of the eye, and careful evaluation is required for determining indications. A second opinion allows verification of the appropriateness of preoperative screening, overlooked contraindications, suitability of surgical technique selection, and management of postoperative complications from a third-party perspective.

A test to detect aqueous humor leakage from a full-thickness corneal or scleral defect using fluorescein staining and cobalt blue light. It is essential for confirming wound closure in open globe injuries and after surgery.

A slate-gray, elongated oval area appearing posterior to the corneal limbus and anterior to the insertion of the horizontal rectus muscles, characterized by hyaline degeneration and calcification of the sclera. Usually asymptomatic and requires no treatment, but rarely leads to senile scleral softening.

As blood-derived eye drops, they are used for ocular surface diseases resistant to conservative treatments such as severe dry eye and persistent corneal epithelial defects. There are autologous serum (AS) and allogeneic serum (ALS), which contain growth factors, vitamins, and fibronectin similar to natural tears, promoting ocular surface repair.

Corneal decompensation caused by contact and emulsification of silicone oil on the corneal endothelium following silicone oil tamponade after vitrectomy. It leads to band keratopathy and bullous keratopathy.

A one-stage surgical technique for limbal stem cell deficiency (LSCD) reported by Sangwan et al. in 2012. A small amount of limbal tissue is harvested from the healthy eye, divided into small pieces on amniotic membrane, and allowed to proliferate in vivo. No special culture equipment is required, and it is cost-effective.

An experimental procedure that reuses the corneal stromal lenticule extracted during SMILE surgery as a homologous corneal inlay for the treatment of hyperopia, presbyopia, keratoconus, corneal thinning, and other conditions.

A degenerative disease in which yellowish-brown spherical protein deposits accumulate beneath the epithelium of the cornea and conjunctiva. Ultraviolet exposure and aging are major risk factors, and it commonly occurs in the interpalpebral fissure. Usually asymptomatic, but if it extends to the pupillary area, it can cause vision loss.

An acute disease characterized by erosions and blisters on the skin and mucous membranes throughout the body, triggered by medications or infections. Ocular complications are the most important sequelae, with corneal opacity due to loss of corneal epithelial stem cells and severe dry eye persisting throughout life.

A benign ocular surface disease in which blood accumulates in the subconjunctival space due to rupture of conjunctival vessels. It appears as a bright red to dark red hemorrhage patch and is naturally absorbed in most cases. Systemic evaluation is required for recurrent cases.

An extremely rare autosomal dominant corneal dystrophy characterized by deposition of chondroitin-4-sulfate and dermatan sulfate beneath the corneal epithelium. It presents with recurrent corneal erosions in childhood and progressive vision loss in adulthood.

Superficial punctate keratitis (SPK) is a finding in which the outermost cells of the corneal epithelium are shed in a punctate pattern. It arises from various causes including dry eye, meibomian gland dysfunction, drug toxicity, allergies, contact lens-related disorders, and Thygeson superficial punctate keratitis. The cause can be inferred from the staining pattern, and treatment is selected accordingly, including artificial tears, diquafosol, rebamipide, corneal protective agents, and low-concentration steroid eye drops.

A chronic inflammatory disease of unknown cause localized to the superior bulbar conjunctiva and corneal limbus. It is often associated with thyroid dysfunction and dry eye. Increased friction with the upper eyelid during blinking is considered central to the pathogenesis.

A condition in which the bulbar conjunctiva and palpebral conjunctiva become abnormally adherent. It often occurs after conjunctival epithelial damage such as chemical trauma, Stevens-Johnson syndrome, or ocular pemphigoid. It can cause impaired eye movement, shortening of the conjunctival fornix, and decreased vision.

Non-ulcerative keratitis caused by Treponema pallidum infection. It is most common as a late manifestation of congenital syphilis and is considered one of Hutchinson's triad. The immune response is central to the pathology, and topical steroids are the first-line treatment.

A temporary artificial cornea device used to secure the surgical field during vitreoretinal surgery in eyes with corneal opacity. Representative types include the Landers type (made of PMMA) and the Eckardt type (made of silicone). It is removed after vitreoretinal surgery and replaced with a full-thickness corneal transplant.

A rare degenerative disease characterized by non-inflammatory thinning of the peripheral cornea with lipid deposition and superficial neovascularization. It slowly progresses circumferentially from the superior quadrant, causing high irregular astigmatism and perforation triggered by minor trauma.

An autosomal dominant Bowman layer dystrophy caused by the Arg555Gln mutation in the TGFBI gene. It is characterized by honeycomb-shaped corneal opacities and recurrent corneal epithelial erosions. A sawtooth pattern on anterior segment OCT and curly collagen fibers on electron microscopy are useful for diagnosis.

An idiopathic recurrent bilateral corneal epitheliopathy. Gray-white elevated punctate opacities are scattered in the central cornea without conjunctival inflammation. An association with HLA-DR3 has been suggested. Low-dose steroid eye drops and cyclosporine eye drops are effective. Visual prognosis is good, and it resolves without scarring.

A severe corneal disorder caused by abuse of topical anesthetics. It presents with persistent corneal epithelial defects, ring-shaped stromal infiltration, and stromal edema. Differentiation from Acanthamoeba keratitis is important. The principle of treatment is immediate discontinuation of anesthetics, along with introduction of alternative analgesia and psychiatric intervention.

An extremely rare autosomal recessive disorder caused by mutations in the ASPH gene. It is characterized by four major features: facial dysmorphism, lens dislocation, anterior segment abnormalities, and spontaneous filtering blebs. Impaired hydroxylation of EGF domains reduces the stability of the zonules, leading to progressive ocular complications.

A chronic conjunctivitis caused by repeated infection with ocular serotypes A to C of Chlamydia trachomatis, and the leading infectious cause of blindness worldwide. It progresses from conjunctival follicles and papillary hypertrophy to scarring, trichiasis, and corneal opacity. The WHO SAFE strategy (Surgery, Antibiotics, Facial cleanliness, Environmental improvement) is promoted for its elimination.

A condition in which the eyelashes grow in an abnormal direction toward the eyeball, distinguished from entropion by the absence of eyelid malposition. It can be caused by various factors such as trachoma, chronic blepharitis, trauma, Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and chemotherapy. Treatment is selected based on severity, ranging from epilation to electrolysis, follicle excision, and tarsal rotation surgery.

A transient corneal edema that occurs during prolonged physical exertion such as ultramarathons. It is thought to be caused by lactate accumulation in the cornea, presenting with painless progressive blurred vision, and resolves within hours after stopping exercise. Protective eyewear and lubricating eye drops are recommended for prevention.

Urets-Zavalia syndrome (UZS) is a rare complication after ophthalmic surgery in which the pupil becomes dilated and fixed, unresponsive to light or miotics. It is mainly reported after penetrating keratoplasty, but also occurs after many other ophthalmic surgeries such as cataract surgery, DALK, DSAEK, and phakic intraocular lens implantation. The main pathophysiology is thought to be necrosis of the pupillary sphincter due to iris ischemia.

Vernal keratoconjunctivitis (VKC) is an allergic conjunctival disease accompanied by proliferative changes in the conjunctiva. It commonly occurs in boys during childhood and presents characteristic findings such as cobblestone papillae and Horner-Trantas dots. Based on the Japanese Guidelines for the Diagnosis and Treatment of Allergic Conjunctival Diseases, 3rd Edition (2021), treatment centers on immunosuppressive eye drops (cyclosporine and tacrolimus).

This is a corneal complication of herpes zoster ophthalmicus (HZO) associated with reactivation of varicella-zoster virus (VZV). Stromal keratitis (VZV-SK) primarily involves immune-mediated inflammation of the corneal stroma, leading to nummular infiltrates and corneal scarring. Endotheliitis (VZV-E) is characterized by keratic precipitates and corneal edema. The mainstay of treatment for both conditions is a combination of topical steroids and antiviral agents, and gradual tapering of steroids is important to prevent recurrence.

A Wessely immune ring is a sterile ring-shaped infiltration that occurs as an immune reaction in the corneal stroma to foreign antigens. It appears in association with infectious keratitis (e.g., Pseudomonas aeruginosa, Acanthamoeba, herpes) and non-infectious factors (e.g., contact lenses, laser treatment), and immune complex-mediated complement activation is central to its pathogenesis.

Wilson disease is a copper metabolism disorder caused by mutations in the ATP7B gene, characterized by three main features: liver disease, extrapyramidal symptoms, and corneal Kayser-Fleischer rings. Kayser-Fleischer rings are copper deposits at the level of Descemet's membrane and are an important ophthalmic finding for diagnosis. Copper chelating agents and zinc therapy can reduce or resolve Kayser-Fleischer rings.

X-linked corneal endothelial dystrophy (XECD) is an extremely rare posterior corneal dystrophy reported only in a single Austrian family. It shows X-linked dominant inheritance, with males presenting congenital ground-glass corneal opacities and nystagmus, while females remain asymptomatic with only moon-crater-like endothelial changes.

Xerophthalmia is a general term for a series of eye diseases caused by vitamin A deficiency. It progresses through stages: night blindness, conjunctival xerosis, Bitot's spots, corneal xerosis, and keratomalacia, leading to irreversible blindness if not treated appropriately.