Browse plain-English disease and condition guides, including symptoms, causes, diagnosis, treatment options, prevention, and when to seek medical care.
Persistent Hyperplastic Primary Vitreous (PHPV)—now more often called Persistent Fetal Vasculature (PFV) is a congenital (present at birth) eye condition. In a developing baby, the eye has...
Read articleAblepharon-Macrostomia Syndrome (AMS) is an extremely rare, autosomal dominant genetic disorder characterized principally by absent or underdeveloped eyelids (“ablepharon”) and an unusually wide, fish-like mouth (“macrostomia”)...
Read articleAcanthamoeba keratitis is a rare but potentially sight-threatening corneal infection caused by the free-living amoeba Acanthamoeba, which is found ubiquitously in soil, fresh water, and even...
Read articleAccommodative esotropia is a common form of childhood strabismus in which one or both eyes turn inward (esodeviation) because of excessive focusing (accommodation) linked to farsightedness...
Read articleAchromatopsia is a rare eye condition that affects how a person sees color. People with achromatopsia typically have trouble seeing colors or can only see them...
Read articleAchromatopsia is a rare, inherited vision disorder that causes a complete or partial inability to see color. People with achromatopsia rely almost entirely on their rod...
Read articleAchromatopsia 2 (ACHM2) is a genetic eye condition that starts from birth. It mainly affects the cone cells in the retina, which are the light-sensing cells...
Read articleAcquired Developmental Prosopagnosia, often referred to as ADP, is a condition that affects a person’s ability to recognize faces. It’s a complex condition, and in this...
Read articleAcquired ectropion uveae (AEU) is a condition in which the pigmented posterior layer of the iris—normally hidden on the back surface—becomes adherent to and everts onto...
Read articleAcquired oculomotor nerve palsy is a non-congenital condition in which the third cranial nerve (oculomotor nerve) becomes damaged after birth, leading to dysfunction of most extraocular...
Read articleAcquired ophthalmoparesis is a condition characterized by weakness or paralysis of one or more extraocular muscles—those that control eye movements—due to processes that occur after birth....
Read articleAcquired Orbital Dysmorphia (AOD) is a medical condition that affects the structure and appearance of the eye socket and surrounding areas. In simpler terms, it means...
Read articleBirdshot choroidal lesions are pale, oval or round spots deep in the back of the eye. They sit in the choroid, which is the layer that...
Read articleBirdshot chorioretinitis is a rare, long-lasting (chronic) inflammation inside both eyes. It mainly affects the back of the eye: the choroid (the blood-vessel layer under the...
Read articleBirdshot chorioretinopathy (BCR) is a rare, long-lasting inflammation inside both eyes. It affects the choroid (the blood-rich layer under the retina) and the retina (the light-sensing...
Read articleBilateral Acute Depigmentation of the Iris (BADI) is a rare eye condition where both irises suddenly lose their brown/blue/green color in patches or diffusely. The pigment...
Read articleBietti crystalline retinopathy (BCR)—also called Bietti crystalline corneoretinal dystrophy—is a rare, inherited eye disease. Tiny yellow-white crystals and lipid deposits gradually build up in the retina...
Read articleBietti crystalline corneoretinal dystrophy is a rare, inherited eye disease. Tiny yellow-white crystals made of lipids (fats) collect in the retina and sometimes in the cornea....
Read articleOuvrier–Billson syndrome is a rare neuro-ophthalmic condition in babies and young children. During “spells,” the child’s eyes hold a fixed upward gaze, often for minutes to...
Read articleNeuroocular syndrome 2, paroxysmal type (NOC2)”—a disorder best known for recurrent upward eye deviation (or vertical nystagmus) with abnormal head posturing from infancy, often with ataxia...
Read articleBenign concentric annular macular dystrophy (BCAMD) is a rare, inherited eye condition that slowly changes the macula—the central part of the retina that gives sharp, detailed...
Read articleHemifacial hyperplasia-strabismus syndrome is a very rare condition where one side of the face grows more than the other, and the person also has eye misalignment...
Read articleOculo-cerebral dysplasia describes very rare developmental conditions present from birth in which eye structures and the brain form abnormally, often alongside other issues like muscle tone...
Read articleBehrens-Baumann-Vogel syndrome is a very rare birth condition that affects the eyes and the brain. Babies are born with very small eyes (microphthalmia) and severe problems...
Read articleAxenfeld-Rieger syndrome (ARS) is a rare genetic condition that mainly affects the front part of the eye (the “anterior segment”). It changes the way the iris,...
Read articleCombined Granular-Lattice Corneal Dystrophy Type 2 is an inherited corneal dystrophy caused most commonly by the R124H mutation in the TGFBI (TGFBIp) gene. Abnormal protein deposits...
Read articleAvellino corneal dystrophy is a genetic eye condition. A change (mutation) in the TGFBI gene makes a sticky, abnormal protein collect in the clear front window...
Read articleProgressive external ophthalmoplegia (PEO) is a mitochondrial muscle condition where the muscles that move the eyes slowly become weak. Over years, people develop droopy eyelids (ptosis)...
Read articleRetinopathy, Burgess-Black type is a rare, inherited eye disease caused by harmful changes (mutations) in both copies of a gene called BEST1. This gene helps the...
Read articleBestrophinopathy is an umbrella term for several inherited eye conditions caused by changes (variants) in a gene called BEST1. This gene helps retinal pigment epithelium (RPE)...
Read articleAutosomal recessive bestrophinopathy (ARB) is a rare, inherited eye disease. It happens when a child receives two faulty copies of a gene called BEST1—one from each...
Read articleVitreoretinochoroidopathy with microcornea is a rare, inherited eye disease in which several parts of the eye develop and function abnormally. The back of the eye (the...
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