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 articleScleritis is inflammation of the sclera, which is the strong white wall of the eye. The sclera gives the eye its firm shape and protects the...
Read articleSchwartz–Matsuo syndrome is sudden or fluctuating high eye pressure that happens at the same time as a rhegmatogenous retinal detachment. In SMS, the drainage filter of...
Read articleSchwartz–Matsuo syndrome is a rare eye problem where eye pressure becomes very high at the same time as a rhegmatogenous retinal detachment (a “tear with fluid...
Read articleSchwartz-Jampel syndrome is a rare, genetic condition that affects muscles and bones. In very simple terms: the muscles stay too tight and do not relax easily...
Read articleSchnyder corneal dystrophy is a rare, inherited eye condition in which fat-like substances—mainly cholesterol and certain phospholipids—slowly build up inside the clear front window of the...
Read articleSaturday Night Retinopathy is a rare eye emergency. It happens when someone becomes deeply unconscious—most often after heavy alcohol use or sedating drugs—and lies face-down or...
Read articleSarcoid uveitis is eye inflammation that happens when a person has sarcoidosis, a condition where the immune system forms tiny clumps of inflammatory cells called granulomas...
Read articleSanjad-Sakati Syndrome (SSS)—also called HRD syndrome (hypoparathyroidism–retardation–dysmorphism)—is a very rare, inherited condition. Children are born with underactive parathyroid glands (hypoparathyroidism), which causes low blood calcium, high...
Read articleSalzmann Nodular Degeneration is a slow eye surface problem of the clear front window of the eye called the cornea. In this condition, small, raised, gray-white...
Read articleSagging Eye Syndrome is an age-related problem of the soft “guy-wires” and pulleys that guide your eye muscles. With age, a key strap of tissue that...
Read articleSaethre-Chotzen syndrome is a genetic condition where some of the flexible seams between skull bones (called sutures) close too early. When these seams close too soon,...
Read articleSaccadic intrusions are brief, unwanted, fast eye jumps that interrupt steady looking. Your eyes are trying to hold still on a target, but a sudden, quick...
Read articleA saccade is a very fast eye movement that jumps your line of sight from one spot to another spot. Your eyes do not slide smoothly...
Read articleA ruptured globe is a full-thickness tear of the wall of the eye after a strong blunt blow. The eye has a tough outer coat made...
Read articleRowland Payne Syndrome is a neuro-anatomical triad—three problems that usually happen on the same side of the neck and chest—caused by a single area of damage...
Read articleRoth spots are small bleeds inside the retina—the light-sensitive tissue at the back of the eye—with a pale or white center in the middle of the...
Read articleRoss syndrome is a rare disorder of the autonomic nervous system (the automatic nerves that control sweating, pupil size, and reflexes). Doctors recognize it by a...
Read articleRosai–Dorfman disease (RDD)—also called sinus histiocytosis with massive lymphadenopathy—is a rare disorder where a specific type of immune cell called a histiocyte grows and gathers in...
Read articleRho-kinase inhibitor–associated corneal epithelial edema is a temporary swelling of the surface layer (epithelium) of the cornea that appears after using ROCK-inhibitor glaucoma drops such as...
Read articleRhinosporidiosis is a long-lasting infection that mainly grows on moist lining tissues of the nose, throat, and eyes. It is caused by a microscopic organism called...
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