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 articleSilent Brain Syndrome is a rare eye-orbit condition that usually appears years after a child has been treated for hydrocephalus with a ventriculo-peritoneal shunt. In this...
Read articleElschnig spots are tiny, round marks that an eye doctor can see on the back of the eye when the pupil is dilated and the retina...
Read articleSiegrist streaks are thin, straight lines of dark pigment that you can see in the back of the eye when a doctor looks with a dilated...
Read articleSiderosis means iron builds up inside body tissues and stays there as tiny brown particles called hemosiderin, which is iron stored in a safe but heavy...
Read articleSickle cell retinopathy is an eye disease that happens in people who carry sickle hemoglobin in their red blood cells. In sickle cell disease, red blood...
Read articleSickle cell maculopathy is damage in the center of the retina called the macula that happens in people who have sickle cell disease. The macula is...
Read articleSeasonal Hyperacute Pan-Uveitis (SHAPU) is a very sudden and very strong inflammation inside the eye. “Pan-uveitis” means the inflammation involves the whole uveal tract of the...
Read articleAbusive Head Trauma is a serious brain injury in a baby or young child. It happens when a caregiver violently shakes a child, hits the head,...
Read articleSeven Rings of Trauma” is an eye-trauma concept used mostly in ophthalmology. It describes seven circular (ring-like) tissues in the front half of the eye that...
Read articleSerpiginous choroidopathy is a rare inflammation in the back of the eye. It mainly involves three layers: the choroid (the blood-rich layer under the retina), the...
Read articleSeronegative myasthenia gravis is a long-term immune system disease that makes muscles weak and tired. It affects the place where nerves talk to muscles. This place...
Read articlePeriorbital malignancy means a cancer that starts in the skin of the eyelid or the tissues right next to the eye. It can grow on the...
Read articleSenile scleral plaque is an age-related change in the white coat of the eye, which doctors call the sclera. It looks like a flat, well-defined, slate-gray...
Read articleSenile retinoschisis—also called degenerative retinoschisis—is a common, age-related eye condition where the retina (the thin, light-sensing tissue at the back of the eye) splits into two...
Read articleSecondary acquired nasolacrimal duct obstruction means the normal tear-drainage tube in the nose gets blocked because of another disease, injury, treatment, or outside cause. The “nasolacrimal...
Read articleSeborrheic keratosis is a benign (non-cancerous) skin growth that looks like a small plaque or wart that is “stuck on” the skin surface. The growth is...
Read articleSebaceous carcinoma is a cancer that grows from oil-making glands in the skin. These oil-making glands are called sebaceous glands. They make sebum, which is a...
Read articleScleromalacia perforans is a rare eye problem where the tough white coat of the eye (the sclera) becomes very thin and weak in quiet, non-red areas....
Read articleSclerocornea is a rare eye condition that is usually present at birth. In this condition, the clear front window of the eye (the cornea) looks white...
Read articleSclerochoroidal calcification means tiny to small lumps or plaques of calcium salts have settled inside the white wall of the eye (the sclera). With time, this...
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