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A very rare congenital syndrome characterized by distinctive craniofacial features, congenital cataracts, microphthalmia, hypotrichosis, skin atrophy, and proportionate short stature. Approximately 90% of cases have ocular findings, requiring multidisciplinary management.

A rare disorder in which visual distortions or flashbacks persist after hallucinogen use. It is classified into two types, HPPD I and HPPD II, and this article explains diagnostic criteria, treatment, and pathophysiology.

HaNDL syndrome is a self-limited secondary headache disorder characterized by transient headache and neurological deficits accompanied by cerebrospinal fluid lymphocytosis. It may present with ophthalmologic findings such as papilledema and abducens nerve palsy.

This article explains the indications, prescription, fitting, and complication management of rigid gas permeable (RGP/hard) contact lenses for keratoconus. It provides a practical, detailed description including base curve selection using BFS values from anterior segment OCT (Itoi Method), fluorescein pattern evaluation, and criteria for transitioning to scleral lenses.

Harding disease is a rare condition in which Leber hereditary optic neuropathy (LHON) and multiple sclerosis (MS) coexist. It causes painless, severe vision loss against a background of mitochondrial DNA mutations, and no established treatment exists.

A rare syndrome of autonomic nervous system dysfunction characterized by unilateral facial flushing and hyperhidrosis with contralateral pallor and anhidrosis. May be associated with Horner syndrome.

Hashimoto encephalopathy (SREAT) is a rare autoimmune encephalopathy associated with elevated antithyroid antibodies. It presents with seizures, cognitive impairment, and psychiatric symptoms, and responds well to steroid therapy.

An acquired strabismus caused by elongation of the eyeball in high myopia, where the posterior part of the eye dislocates from the muscle cone, leading to deviation of extraocular muscle paths and progressive esotropia and hypotropia. Diagnosis by coronal MRI and the superior rectus-lateral rectus suture technique (Yokoyama procedure) are explained.

A rare subtype of sarcoidosis characterized by four main symptoms: anterior uveitis, parotid gland swelling, facial nerve palsy, and fever. Also known as uveoparotid fever, it occurs in 4–6% of sarcoidosis patients.

Heimann-Bielschowsky phenomenon (HBP) is a unilateral, slow pendular vertical nystagmus occurring in an eye with severe visual impairment. This article explains its diagnosis, differential diagnosis, and treatment.

Infantile hemangioma of the eyelid (formerly called strawberry hemangioma) is the most common benign vascular tumor in infancy, and 70% regress spontaneously before school age. Oral propranolol is the first-line treatment when there is a risk of form deprivation amblyopia due to difficulty opening the eyelid.

Hemifacial spasm (HFS) is a movement disorder characterized by involuntary tonic-clonic contractions of the facial muscles on one side of the face. Vascular compression of the facial nerve is the main cause, and it is treated with botulinum toxin injections or microvascular decompression.

Explains intraocular pressure fluctuations during hemodialysis and the pathophysiology, risk factors, diagnosis, and treatment of ocular dialysis disequilibrium syndrome (ODD). Details the effects of osmotic gradients on aqueous humor dynamics, optimization of dialysis prescriptions, and management in glaucoma patients.

An extremely rare retinal vasculitis that occurs after intracameral vancomycin administration during cataract surgery. Explains diagnostic criteria, clinical findings, treatment, and prevention.

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.

An autosomal dominant genetic disorder characterized by hyperferritinemia without iron overload and early-onset bilateral cataracts, caused by an IRE mutation in the FTL gene leading to overproduction of L-ferritin. Differentiation from hereditary hemochromatosis is important.

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.

Anterior uveitis caused by intraocular reactivation of herpes simplex virus (HSV). It is a representative cause of unilateral anterior uveitis with elevated intraocular pressure, accounting for 5–10% of all uveitis cases.

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.

Optic neuritis occurring as a rare complication of herpes zoster ophthalmicus (HZO). Varicella-zoster virus (VZV) damages the optic nerve, causing vision loss.

Anterior or posterior uveitis caused by reactivation of varicella-zoster virus (VZV). It occurs in 40–60% of herpes zoster ophthalmicus (HZO) cases and is characterized by elevated intraocular pressure, chronicity, and sectoral iris atrophy.

A clinical test to record dysfunction or overaction of the extraocular muscles and evaluate incomitant strabismus. This article explains the Hess chart, which uses red-green goggles to diagrammatically record ocular deviation.

A disease characterized by retinal hemorrhage and papilledema caused by the low-pressure, hypoxic environment at high altitudes. Explains the Wiedman-Tabin classification, diagnosis, prevention, and treatment.

This article explains preoperative evaluation, IOL power calculation, intraoperative complications, and postoperative management in cataract surgery for high myopia. It covers unique challenges associated with axial elongation and improved accuracy using AI-driven new-generation formulas.

This article chronologically explains the evolution of cataract surgery, from ancient couching to modern phacoemulsification and femtosecond laser surgery.

This article explains the historical evolution of the recognition, diagnosis, and treatment of glaucoma, from the ancient Greek term "glaukos" to modern MIGS. It details the invention of the ophthalmoscope, development of the tonometer, advances in pharmacotherapy (miotics, beta-blockers, prostaglandin analogs), surgical treatments (iridectomy, trabeculectomy, tube shunt, MIGS), and the prospects of gene therapy.

Neuro-ophthalmology began with ancient Greek theories of vision, developed through accumulating anatomical discoveries and the specialization of the field in the 19th and 20th centuries, and was established as a subspecialty by Frank Walsh.

A historical overview that traces the origins of oculoplastic surgery from ancient times and explains how the main procedures of eyelid reconstruction, ptosis surgery, lacrimal surgery, and orbital surgery developed.

Acute, recurrent non-granulomatous anterior uveitis that frequently occurs in HLA-B27-positive individuals. It is commonly associated with spondyloarthropathies such as ankylosing spondylitis and presents with acute eye pain, photophobia, and redness. This article explains diagnosis, treatment, and indications for biologic agents based on the uveitis clinical practice guidelines.

This article explains the background, principles, devices, and clinical significance of home intraocular pressure measurement (home tonometry). It details the features and limitations of the iCare HOME rebound tonometer, Triggerfish contact lens sensor, and EyeMate implantable sensor, as well as the importance of out-of-office intraocular pressure monitoring.

A congenital amino acid metabolism disorder caused by deficiency of cystathionine beta-synthase (CBS). It is an autosomal recessive disease that frequently involves lens dislocation, skeletal abnormalities, thromboembolism, and intellectual disability.

A visual field defect affecting the same side of both eyes caused by damage to the posterior visual pathway (optic tract, lateral geniculate body, optic radiation, occipital visual cortex). Cerebrovascular disease (infarction or hemorrhage in the posterior cerebral artery territory) is the most common cause. The presence or absence of macular sparing and the quadrantanopia pattern help localize the lesion.

Horner syndrome is a syndrome characterized by the triad of miosis, ptosis, and anhidrosis due to disruption of the ocular sympathetic pathway. It is classified into central, preganglionic, and postganglionic types, and is diagnosed by pharmacological pupil testing and the apraclonidine test. It is essential to rule out serious causes such as carotid artery dissection and Pancoast tumor.

Explains how to get a second opinion in ophthalmology, how to obtain a referral letter (medical information letter), costs, and insurance coverage. Summarizes when a second opinion is helpful, such as when deciding whether surgery is needed, diagnosing hard-to-treat conditions, or after receiving an important explanation, and the points for using it well.

Granulomatous or non-granulomatous uveitis occurring in carriers of human T-cell leukemia virus type 1 (HTLV-1). Common in Kyushu, Okinawa, and southern Shikoku, characterized by distinctive veil-like vitreous opacities and retinal vasculitis. Responds well to steroids but recurs in about 60% of cases.

Explains the SITA algorithm, test program selection, result interpretation, Anderson-Patella criteria, GHT/MD/VFI/PSD indices, and progression assessment for Humphrey static perimetry (HFA). It is the standard visual field test for glaucoma diagnosis and management.

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.

A technique for separating lens tissue using fluid flow during cataract surgery. Centered on two procedures—hydrodissection and hydrodelineation—it is a fundamental maneuver that achieves nucleus mobilization, cortex removal, and posterior capsule protection.

A treatment that administers 100% oxygen under high pressure of 1.4 ATA or higher. Central retinal artery occlusion (CRAO) is the only ophthalmic indication approved by UHMS, and off-label use has been reported for other eye diseases such as diabetic retinopathy and optic neuropathy. Attention should also be paid to ophthalmic complications such as hyperoxic myopia and cataracts.

Hyperopia is a refractive error in which parallel light rays focus behind the retina. This article covers detection of latent hyperopia, its association with accommodative esotropia and amblyopia, and the importance of early correction in children.

Hyperreflective foci (HRF) observed on optical coherence tomography (OCT) are biomarkers of inflammation and degeneration found in various ocular diseases such as uveitis, age-related macular degeneration, and diabetic retinopathy.

Small hyperreflective lesions less than 30 μm detected by optical coherence tomography (OCT). They are attracting attention as biomarkers of inflammation and degeneration in various retinal diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma.

Hypertension and dyslipidemia are risk factors for hypertensive retinopathy, retinal vein occlusion, retinal artery occlusion, and ischemic optic neuropathy. The ocular fundus is the only part of the body where blood vessels can be directly observed, playing an important role in assessing cardiovascular risk.

A disease in which retinal blood vessels are damaged by systemic hypertension. Through vasospasm, arteriosclerosis, and breakdown of the blood-retinal barrier, fundus changes such as hemorrhages, exudates, and papilledema occur. Severe cases are also a risk indicator for cardiovascular disease and stroke.

Hypertropia is a vertical strabismus in which one eye is deviated upward relative to the other. The most common cause is superior oblique muscle palsy, which can be congenital or acquired. Diagnosis involves the Parks three-step test and the Bielschowsky head tilt test. Treatment options include prism correction and strabismus surgery, depending on the cause.

A condition in which blood accumulates in the anterior chamber (between the cornea and iris). Blunt trauma is the most common cause, and it can lead to vision-related complications such as elevated intraocular pressure and corneal blood staining.

This article explains the diagnostic criteria, pathophysiology, and treatment of hypnic headache, a rare primary headache that occurs only during sleep and causes awakening.

Definition of hypotony maculopathy, threshold intraocular pressure (8–10 mmHg), OCT findings of chorioretinal folds and photoreceptor folds, conservative treatment (autologous blood injection, transconjunctival scleral flap suture), and surgical treatment (laser photocoagulation, cyclopexy, bleb revision).

This article explains the pathology, diagnosis, and treatment of hypotropia associated with thyroid eye disease (Graves' ophthalmopathy). It covers the mechanism of restrictive strabismus due to fibrosis of the inferior rectus muscle, indications and surgical techniques for prism therapy and strabismus surgery, and the latest findings on teprotumumab.