High myopia is a severe form of nearsightedness (myopia) in which distant objects appear very blurry while close objects remain clear. In technical terms, it ...

High altitude retinopathy (HAR) is an eye condition that arises when people ascend to high elevations—usually above 2,500 m (about 8,200 ft)—and experience low ...

Herpes Zoster Uveitis is an eye condition in which the varicella-zoster virus (VZV)—the same virus that causes chickenpox and shingles—reactivates and inflames ...

Herpes Zoster Optic Neuritis is a rare but serious inflammation of the optic nerve caused by reactivation of the varicella-zoster virus (VZV)—the same virus ...

Herpes Zoster Ophthalmicus (HZO) is a painful, viral infection of the eye and the surrounding skin, caused by the reactivation of the varicella-zoster virus ...

Herpes Simplex Virus (HSV) Stromal Endotheliitis is a type of eye inflammation caused by the herpes simplex virus affecting the deep layers of the cornea. In ...

Herpes Simplex Virus Stromal Keratitis (often shortened to HSV Stromal Keratitis) is a serious infection of the corneal stroma—the thick, transparent middle ...

Herpes Simplex Uveitis is a form of eye inflammation caused by infection with the herpes simplex virus (HSV). In plain English, “herpes simplex” refers to a ...

Herpes Simplex Epithelial Keratitis (HSEK) is an eye infection affecting the thin, clear front layer of the eye called the corneal epithelium. It is caused by ...

Hereditary Hyperferritinemia Cataract Syndrome (HHCS) is a rare, autosomal dominant genetic disorder characterized by persistently elevated serum L-ferritin ...

Hereditary Benign Intraepithelial Dyskeratosis (HBID) is a rare genetic disorder characterized by the development of white, plaque-like lesions on the surface ...

Hereditary Angiopathy with Nephropathy, Aneurysms, and Muscle Cramps (HANAC) syndrome is a rare genetic disorder caused by mutations in the COL4A1 gene. This ...

Hemorrhagic Occlusive Retinal Vasculitis (HORV) is a rare but serious inflammatory condition affecting the small blood vessels (vasculature) in the retina, the ...

Intraocular pressure is the pressure inside your eye. Think of your eye like a small, flexible ball filled with a clear fluid. That clear fluid in the front ...

Hemifacial spasm is a nervous system disorder characterized by involuntary, irregular muscle contractions on one side of the face. These spasms often begin ...

Hemangiopericytoma (HPC) is a rare vascular tumor that arises from pericytes—cells that wrap around small blood vessels. Recent studies classify it within the ...

Helicoid peripapillary chorioretinal degeneration (HPCD) is a rare, slowly progressive eye disorder characterized by a winding (“helicoid”) band of ...

Heimann–Bielschowsky Phenomenon (HBP) is a type of involuntary eye movement (nystagmus) that occurs in a single, non-seeing (blind) eye. Unlike more common ...

Heerfordt–Waldenström syndrome, also called uveoparotid fever, is a rare form of sarcoidosis. In this condition, tiny clumps of inflammatory cells called ...

Heavy Eye Syndrome (also known as myopic strabismus fixus or strabismus fixus convergence) is a form of acquired eye misalignment (strabismus) that occurs ...