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This article explains the measurement principle of the rebound tonometer iCare, the procedure requiring no topical anesthesia, multi-position measurement with IC200, self-measurement and 24-hour intraocular pressure monitoring with iCare HOME, and accuracy comparison with the Goldmann applanation tonometer.

This article details the pathophysiology of ICE syndrome (iridocorneal endothelial syndrome), its three clinical types (progressive iris atrophy, Chandler syndrome, and Cogan-Reese syndrome), diagnosis using specular microscopy, and treatment strategies ranging from aqueous suppressants to tube shunt surgery and DMEK/DSAEK.

Idiopathic multifocal choroiditis (IMFC) is a bilateral autoimmune disease characterized by multiple inflammatory lesions in the retina and choroid, predominantly affecting young myopic women, with choroidal neovascularization as a serious complication.

An inflammatory disease of the optic nerve caused by autoimmune mechanisms. It predominantly affects women aged 15–45 years, with acute unilateral vision loss and eye movement pain as main symptoms. Visual recovery is expected in over 90% of cases, but anti-AQP4 antibody-positive cases are refractory, and assessment of MS conversion risk is important.

A nonspecific inflammatory disease of unknown cause occurring in the orbit, formerly called "orbital inflammatory pseudotumor." It is defined pathologically by three conditions: nonspecific inflammation, no response to antibiotics, and marked response to steroids. Oral prednisolone is the first-line treatment, tapered over 3 to 6 months. For refractory cases, radiation therapy or methotrexate may be tried.

A systemic disease in which fibroinflammatory lesions rich in IgG4-positive plasma cells occur in the orbit. Painless swelling of the lacrimal gland is the most common symptom (86%), and the mainstay of treatment is steroid tapering therapy or immunosuppressive therapy with rituximab. The 2023 revised diagnostic criteria added a warning about optic neuropathy.

A systemic disease in which fibroinflammatory lesions rich in IgG4-positive plasma cells occur in the orbit. Painless swelling of the lacrimal gland is most common, and immunosuppressive therapy with steroids or rituximab is the mainstay of treatment.

A benign syndrome that commonly occurs in young myopic eyes, presenting with intrapapillary hemorrhage and adjacent peripapillary subretinal hemorrhage (IHAPSH). Most cases resolve spontaneously without treatment, and the visual prognosis is good.

Systematic explanation of imaging techniques used for trauma of the eye and ocular adnexa, including ultrasonography, UBM, OCT, CT, and MRI, covering the principles, indications, findings, and contraindications of each modality.

Explains imaging of the aqueous humor outflow pathway in glaucoma. Covers evaluation of the anterior chamber angle, Schlemm's canal, and collector channels using ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT), as well as gonioscopy, AS-OCTA, and deep learning applications.

Explanation of imaging techniques for the optic nerve and retinal nerve fiber layer (RNFL) in glaucoma. Covers OCT (SD-OCT, SS-OCT), HRT, GDx, fundus photography, RNFL thickness, BMO-MRW, GCC analysis, limitations of normative databases, progression detection, and latest technologies (PS-OCT, AI).

This article explains the indications, contraindications, surgical techniques, complications, and safety protocols for simultaneous bilateral cataract surgery (Immediately Sequential Bilateral Cataract Surgery: ISBCS). It also details the comparison with sequential surgery performed one eye at a time, and the importance of complete sterile separation to prevent endophthalmitis.

Ocular and orbital immune-related adverse events 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.

This article explains the genetic background, clinical features, and treatment of glaucoma associated with immunogenetic diseases (Aicardi-Goutières syndrome, Singleton-Merten syndrome). It also details the pathophysiology due to RIG-I receptor dysfunction and the potential of JAK inhibitors.

Immunomodulatory therapy (IMT) for ocular inflammation is an important treatment strategy to preserve vision in steroid-resistant or steroid-dependent non-infectious uveitis, with a wide range of options from conventional drugs to biologics.

A minimally invasive diagnostic test in which cellulose acetate filter paper is applied to the ocular surface to collect and analyze superficial epithelial cells. It is widely used for diagnosing dry eye, limbal stem cell deficiency, and ocular surface squamous neoplasia.

Inclusion body myositis (IBM) is a slowly progressive inflammatory muscle disease that typically occurs in individuals over 50 years of age. It is characterized by asymmetric weakness of the quadriceps and finger flexors, and rimmed vacuoles. It is resistant to immunosuppressive therapy, and dysphagia and orbicularis oculi muscle weakness are also relevant from an ophthalmological perspective.

Incontinentia pigmenti (Bloch-Sulzberger syndrome) is an X-linked dominant disorder caused by mutations in the IKBKG gene, characterized by four stages of skin lesions as well as ocular complications such as retinal vascular occlusion, neovascularization, and retinal detachment.

A fundus angiography test in which indocyanine green (ICG) is injected intravenously and near-infrared fluorescence is used to visualize choroidal vessels. It is the gold standard for definitive diagnosis of polypoidal choroidal vasculopathy and is essential for evaluating choroidal lesions in age-related macular degeneration, central serous chorioretinopathy, and inflammatory diseases.

Indocyanine green fluorescence fundus angiography (ICGA) explains the principles, procedures, indications, interpretation of findings, and safety. It is a near-infrared fluorescence imaging test that visualizes choroidal vessels.

A large-angle constant esotropia that develops within the first 6 months of life. Early surgical correction is important for achieving binocular vision.

Perioperative strategies for preventing infectious endophthalmitis after cataract surgery. This article explains evidence-based prevention methods including preoperative disinfection, preoperative and postoperative antibiotic eye drops, intracameral antibiotic administration, and incision wound management.

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.

General overview of uveitis caused by viruses, bacteria, fungi, and parasites. A comprehensive hub article explaining classification, diagnostic strategies, indications for intraocular fluid PCR, and the principle of steroid monotherapy contraindication.

A rare eye movement disorder characterized by intermittent involuntary contractions of the inferior oblique muscle, causing excyclotorsion and oscillopsia. Idiopathic, with very few reported cases.

This section explains ocular complications such as uveitis, scleritis, and chorioretinopathy associated with Crohn's disease and ulcerative colitis. It focuses on HLA-B27-related acute anterior uveitis, and TNF-α inhibitors can simultaneously control inflammation in the gut and eyes.

Infliximab is a mouse/human chimeric anti-TNF-α monoclonal antibody that plays an important role as a steroid-sparing treatment for refractory non-infectious ocular inflammation, particularly uveitis associated with Behçet's disease and JIA.

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.

Intermediate uveitis is a chronic recurrent intraocular inflammation primarily involving the vitreous and peripheral retina, and includes the entity of pars planitis characterized by snowballs and snowbanks. It is common in young individuals, and macular edema is the main cause of vision loss.

Intermittent exotropia is a type of strabismus in which the eye alignment is normal most of the time but one eye drifts outward when tired or looking at distant objects. It is the most common type of strabismus in children. This article explains its classification, diagnosis, and treatment.

Internal limiting membrane dystrophy (ILMD) is a rare hereditary retinal dystrophy caused by defects in Müller cells, leading to delamination of the internal limiting membrane and cystoid spaces. It presents with a characteristic sheen in the posterior pole and may cause vision loss in later life.

Internuclear ophthalmoplegia (INO) is an eye movement disorder caused by a lesion of the medial longitudinal fasciculus (MLF), characterized by impaired adduction on the ipsilateral side, nystagmus of the contralateral abducting eye, and preserved convergence. When MLF lesion is combined with PPRF/abducens nucleus lesion, one-and-a-half syndrome occurs, with only abduction of the contralateral eye remaining. Multiple sclerosis and cerebrovascular disease are the two main causes, and treatment of the underlying disease is fundamental.

Systematic interpretation of normal and abnormal findings in color fundus photographs. Interpretation of findings of the optic disc, vascular system, hemorrhages, and macula based on color information and morphology.

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.).

This article explains the indications, procedures, drugs, and clinical outcomes of selective ophthalmic artery infusion chemotherapy (IAC) for retinoblastoma, as well as its position in the treatment system in Japan.

A rare complication after cataract surgery in which blood accumulates between the posterior surface of the intraocular lens and the posterior lens capsule.

Intracorneal ring segments (ICRS) are a surgical procedure for corneal ectasia such as keratoconus and pellucid marginal degeneration, in which arcuate implants are inserted into the corneal stroma to correct the shape. The arc shortening effect flattens the central cornea and reduces irregular astigmatism. Combined use with corneal cross-linking (CXL) provides synergistic effects of halting progression and improving shape.

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.

Explains the relationship between intracranial pressure (ICP) and glaucoma. Details the concept of translaminar pressure gradient (TLPG), the cerebrospinal fluid theory of glaucoma, low ICP in normal-tension glaucoma, development of glaucoma after normal pressure hydrocephalus and VP shunt, changes in lamina cribrosa depth, and mechanisms of axonal transport impairment.

Explains the causes, classification, symptoms, CT diagnosis, foreign body removal via PPV, and prognostic factors of intraocular foreign bodies (IOFB). Includes pathophysiology of siderosis and chalcosis, OTS prognosis prediction, and information on the latest removal devices.

A comprehensive hub summarizing types, indications, power calculation, and postoperative visual function of intraocular lenses (IOLs). It organizes monofocal, trifocal, EDOF, toric, and phakic IOLs with comparison tables and power calculation formula selection charts.

A complication after cataract surgery where the intraocular lens shifts from its normal position. Exfoliation syndrome and zonular weakness are major risk factors, causing decreased vision and increased intraocular pressure.

A complication in which the optic part of an intraocular lens (IOL) becomes cloudy after cataract surgery. There are several mechanisms, including calcium deposition and glistening. If visual function is impaired, IOL removal and exchange is required.

This article explains the diagnosis and treatment of primary intraocular lymphoma (PIOL) / vitreoretinal lymphoma (VRL), including diagnosis using the IL-10/IL-6 ratio, treatment outcomes of intravitreal MTX injection, and risk of CNS progression.

This article explains the physiological significance of intraocular pressure (IOP) and various methods of IOP measurement. It details the principles and measurement techniques of the Goldmann applanation tonometer (GAT), as well as the characteristics of non-contact tonometers, rebound tonometers, and dynamic contour tonometers. The effects of central corneal thickness and corneal biomechanics on measurement values, target IOP setting, and continuous IOP monitoring are also discussed.

This article explains the mechanisms, risk factors, and management of acute and chronic intraocular pressure elevation following intravitreal injection of anti-VEGF drugs.

Explains challenges and solutions for intraocular pressure measurement after refractive surgery (LASIK, PRK, RK). Covers accuracy comparison of various tonometers (GAT, DCT, ORA), mechanism of underestimation due to corneal thinning, interface fluid syndrome, and clinical considerations.

Classification, symptoms, diagnosis, and treatment of intraocular vascular tumors (retinal capillary hemangioma, choroidal hemangioma, retinal cavernous hemangioma, retinal arteriovenous malformation, retinal vasoproliferative tumor). Also covers associations with VHL disease and Sturge-Weber syndrome.

A wavefront aberrometry technique used during cataract surgery to verify and optimize intraocular lens (IOL) power. It is particularly useful in eyes with prior refractive surgery and for toric IOL alignment.

Explanation of intraoperative detection methods for occult retinal breaks in rhegmatogenous retinal detachment surgery. Principles and indications of scleral depression, schlieren phenomenon, dye drainage, cryotherapy test, and endoscopic observation.

A syndrome characterized by iris flaccidity, prolapse, and progressive miosis that occurs during cataract surgery in patients with a history of taking α1-adrenergic receptor blockers (such as tamsulosin). Preoperative medication history review and appropriate intraoperative management are important.

A new nucleus processing technique for manual small-incision cataract surgery (MSICS). This procedure reduces induced astigmatism by dividing and removing the lens nucleus within a sclerocorneal tunnel smaller than 6 mm.

Intravitreal injection of anti-VEGF drugs is a standard treatment for retinal vascular diseases such as age-related macular degeneration, diabetic macular edema, and retinal vein occlusion. This article comprehensively covers drug specifics, procedures, disease-specific regimens, and complications.

Intravitreal injection of anti-VEGF drugs is a standard treatment for retinal vascular diseases such as age-related macular degeneration, diabetic macular edema, retinal vein occlusion, and retinopathy of prematurity. This article comprehensively covers drug specifics, procedures, disease-specific regimens, and complications.

A progressive cataract in which the lens cortex liquefies and swells, increasing intra-lenticular pressure. Anterior capsulotomy during surgery is difficult, requiring special preoperative evaluation and intraoperative measures.

A rare phenomenon in which the eyeball deviates downward and inward during forced eyelid closure. It most commonly occurs after ptosis surgery and usually resolves spontaneously within days to months.

A technique in which the internal limiting membrane (ILM) peeled during macular hole surgery is inverted to cover the hole. It achieves a high closure rate in cases that are difficult to close with standard surgery, such as large, chronic, or myopic macular holes.

This article explains the challenges and solutions for IOL power calculation during cataract surgery in patients with corneal ectasia, such as keratoconus and post-refractive surgery ectasia. The use of corneal tomography and keratoconus-specific formulas is key.

Explains the pathophysiology, three clinical types, diagnosis, and treatment of iridocorneal endothelial syndrome (ICE syndrome). Details the features of Chandler syndrome, progressive iris atrophy, and Cogan-Reese syndrome, diagnosis using specular microscopy and AS-OCT, and treatment strategies including aqueous suppressants, trabeculectomy, tube shunt, and corneal endothelial transplantation.

A condition in which the iris root is torn from the ciliary body attachment and detached from the scleral spur due to blunt trauma. It can cause pupillary deviation, monocular diplopia, and photophobia. It is repaired by iris suturing using the modified Siepser method or McCannel method.

This article explains the indications, technique, treatment outcomes, and complications of argon laser peripheral iridoplasty (ALPI). It details the actual laser treatment for acute primary angle closure and plateau iris syndrome.

Iridoschisis is a rare degenerative disease in which the anterior and posterior layers of the iris stroma separate, and the anterior layer fibers become free in the aqueous humor. It is frequently associated with angle-closure glaucoma and corneal endothelial damage, and cataract surgery requires special considerations.

Iris coloboma is a congenital condition caused by incomplete closure of the embryonic fissure, resulting in a defect in the lower part of the iris. It is characterized by a keyhole-shaped pupil and may be associated with choroidal or optic nerve involvement. This article explains the classification, diagnosis, treatment, and genetic background.

An iris cyst is a fluid-filled sac that forms in the iris. It is classified as primary (pigment epithelial cyst or stromal cyst) or secondary (traumatic, postoperative, or drug-induced). Most are asymptomatic, but large cysts can cause glaucoma or corneal endothelial damage.

This article explains the definition, diagnosis, and treatment of cystic lesions occurring in the iris, focusing on two types: iris stromal cyst and iris pigment epithelial cyst.

This article explains the diagnosis, genetic mutations, treatment, and prognosis of primary malignant melanoma of the iris, which accounts for about 2% of uveal melanomas. It tends to have a lower malignancy compared to those arising from the choroid and ciliary body.

Congenital benign cystic lesions at the pupillary margin. Derived from iris pigment epithelium, usually follow a benign course, but can be an ocular marker for familial aortic disease associated with ACTA2 gene mutations.

A minute, tangled vascular lesion at the pupillary margin (also called Cobb tuft or iris vascular tuft). Usually asymptomatic, but can cause spontaneous hyphema or secondary glaucoma; a rare benign vascular lesion.

This article explains the definition, differential diagnosis, follow-up, and treatment strategy for benign pigmented tumors derived from iris melanocytes.

Detailed explanation of indications, techniques (Siepser method, McCannel method, SFT method), and postoperative outcomes of iris suture (pupilloplasty) for congenital iris coloboma, trauma, and iris damage after cataract surgery. Also explains the criteria for choosing between iris repair and artificial iris devices.

A rare condition characterized by posterior bowing of the peripheral iris and adhesion of the iris to the anterior lens surface. It occurs in association with retinal detachment, hypotony, and intraocular inflammation, and presents with a deep anterior chamber, opposite to iris bombe.

Iris synechiae is a condition in which the iris adheres to adjacent structures due to intraocular inflammation, and is broadly classified into posterior synechiae and peripheral anterior synechiae. It is an important complication of uveitis and can cause secondary glaucoma and visual impairment.

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.

Iris varix is a benign lesion characterized by abnormal dilation and tortuosity of iris blood vessels. It is often asymptomatic, unilateral, and follows a stable course over the long term.

A serious intraoperative complication during cataract surgery where irrigation fluid passes through the zonules and misdirects posteriorly, causing anterior chamber shallowing and elevated intraocular pressure via a ciliary block-like mechanism. Early recognition and appropriate intraoperative management determine visual prognosis.

Non-congenital cataract that can develop in children as a side effect of CFTR modulators including ivacaftor, used to treat cystic fibrosis (CF). Regular ophthalmic screening is recommended.

Non-congenital cataract occurring in children taking ivacaftor, a treatment for cystic fibrosis (CF). Visual impact is often minor, but regular ophthalmic screening is recommended.