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 articleAutosomal dominant iridogoniodysgenesis (IGDS) is a rare, inherited eye condition where parts at the front of the eye do not develop normally before birth. The main...
Read articleAnterior segment dysgenesis is an umbrella term for a group of eye conditions that happen when the front part of the eye does not form normally...
Read articleIschemic Optic Neuropathy (ION) means sudden vision loss because blood flow to the optic nerve is reduced or blocked. It comes in two main locations: anterior...
Read articleAnterior ischemic optic neuropathy (AION) is a sudden drop in vision caused by reduced blood flow to the front part of the optic nerve (the “cable”...
Read articleAnterior segment dysgenesis (ASD) is a group of birth (congenital) conditions where the front parts of the eye—the cornea, iris, lens, and the drainage angle—do not...
Read articleAnterior chamber cleavage disorder (anterior segment dysgenesis, ASD) is a group of birth conditions where the front part of the eye (the cornea, iris, lens, and...
Read articleSyndromic microphthalmia type 3 (MCOPS3) is a rare genetic condition in which a baby is born with very small eyes (microphthalmia) or no visible eye tissue...
Read articleCassia Stocco dos Santos syndrome is an extremely rare condition present from birth that affects several body systems at the same time. Babies with this syndrome...
Read articleMicrophthalmia means a baby is born with one or both eyes that are abnormally small because eye development was interrupted before birth. It exists on a...
Read articleAmaurosis-Hypertrichosis Syndrome is a very rare, inherited condition that affects the eyes and body hair. Babies are born with serious retina problems (the retina is the...
Read articleForsius–Eriksson type ocular albinism—today most often referred to as Åland Islands eye disease (AIED). It is an X-linked retinal channelopathy in which changes in the CACNA1F...
Read articleForsius–Eriksson syndrome—also called Åland Islands eye disease (AIED)—is a very rare eye condition present from birth. It mainly affects boys because the gene change sits on...
Read articleÅland Islands Eye Disease (AIED), also called Forsius–Eriksson syndrome, is a rare, inherited eye condition that mostly affects boys and men because it is X-linked recessive....
Read articleAAID (Alacrima, Achalasia, and Intellectual Disability Syndrome) is a rare, inherited condition. The three core problems are: Alacrima: very low or absent tear production. Eyes feel...
Read articleAlacrima means the eyes do not make enough tears or, in some people, almost no tears at all. Tears are not only “water.” Healthy tears are...
Read articleAdult-onset vitelliform macular dystrophy (AOVMD) is a slow, usually mild, retinal condition that appears in adults, most often between ages 30 and 60. It affects the...
Read articleAdult-onset foveomacular vitelliform dystrophy is a rare, usually slow-moving eye condition that starts in adulthood (often in your 40s–60s). It affects the macula (the center of...
Read articleAcute Zonal Occult Outer Retinopathy, or AZOOR, is a rare eye condition. It starts suddenly. People notice bright flashes of light (called photopsia) and patchy areas...
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 articlePingelapese blindness is a rare, inherited eye condition. People with it see the world in shades of gray. They cannot see color. Bright light hurts their...
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