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 articleA subconjunctival hemorrhage is a small bleed that happens under the clear skin that covers the white part of your eye, and this clear skin is...
Read articleSubclavian Steal Syndrome (SSS) happens when a blockage or severe narrowing in the subclavian artery (the big artery that supplies your arm) “steals” blood away from...
Read articleDiabetic macular edema (DME) is swelling in the very center of the retina (the macula) caused by diabetes. High blood sugar and related changes make the...
Read articleA stye is a small, painful, red lump on the eyelid. It happens when a tiny oil or sweat gland at the edge of the eyelid...
Read articleSturge–Weber syndrome is a rare condition that a person is born with. It affects blood vessels in the skin of the face, in the thin covering...
Read articleStrachan’s disease is a rare nerve and eye disorder. It mainly affects three systems at the same time. The eyes get a type of optic nerve...
Read articleStrabismus means the two eyes are not lined up. One eye points in a slightly different direction than the other eye. Thyroid Eye Disease (TED) is...
Read articleStrabismus fixus is a severe, “stuck” form of eye misalignment. One or both eyes are held in an abnormal position and cannot move normally because something...
Read articleStraatsma syndrome is a rare eye condition where one eye has three things together: a white, feathery patch on the retina called myelinated retinal nerve fibers,...
Read articleStickler syndrome is a genetic condition that affects the eyes, ears, face, joints, and spine. “Genetic” means the change starts in a gene, which is like...
Read articleStevens-Johnson syndrome is a rare but very serious reaction that usually happens after the body is exposed to a trigger, most often a medicine. The reaction...
Read articleIntravitreal endophthalmitis is a severe, sight-threatening infection inside the eye that happens after a tiny needle is used to place medicine into the vitreous gel (the...
Read articleSterile endophthalmitis means that the inside of the eye becomes very inflamed, but there is no living germ causing an infection. The word “endophthalmitis” describes inflammation...
Read articleStereopsis means “seeing depth with two eyes.” It is the brain’s special skill that lets you feel how far or near things are by comparing the...
Read articleRetinoschisis is a change inside the retina, which is the light-sensing “film” at the back of the eye. In retinoschisis, the retina splits into two layers....
Read articleFoveomacular retinoschisis is a problem in the center of the retina. The retina is the thin, light-sensing layer at the back of your eye. The very...
Read articleIdiopathic foveomacular retinoschisis is a retinal splitting problem that happens at the very center of sight. The center of sight is called the fovea. The larger...
Read articleStellate Nonhereditary Idiopathic Foveomacular Retinoschisis (SNIFR) is a pattern of “splitting” inside the macula, the central part of the retina that gives sharp vision. The split...
Read articleStellate multiform amelanotic choroidopathy (SMACH) is a newly described change in the choroid (the vascular layer under your retina). Doctors see a star-shaped (“stellate”) choroidal lesion...
Read articleThe stellate ganglion is a small “relay station” of the sympathetic nervous system in the lower neck/upper chest, made by the fusion of the inferior cervical...
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