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 articleRhino-orbital-cerebral mucormycosis, often shortened to ROCM, is a very serious fungal infection that usually starts in the nose and the sinuses, then can spread to the...
Read articleReversible Posterior Leukoencephalopathy Syndrome is a sudden brain problem that usually gets better when the cause is treated. Doctors also call it Posterior Reversible Encephalopathy Syndrome,...
Read articleA relative afferent pupillary defect (RAPD) is a difference in how the two eyes send light signals to the brain. In a normal system, shining a...
Read articleReversal of Vision Metamorphopsia means a person suddenly sees the whole world turned completely upside down, as if the entire scene has been rotated by 180...
Read articleRetrobulbar hemorrhage means blood collects in the tight space behind the eyeball inside the bony eye socket. The eye socket is like a closed box that...
Read articleRetinopathy of prematurity, or ROP, is an eye disease that happens in some babies who are born too early and too small. The retina is the...
Read articleRetinitis pigmentosa is a group of inherited eye conditions that slowly damage the retina, which is the thin, light-sensing tissue that lines the inside of the...
Read articleRetinal vein occlusion is a blood-flow problem inside the eye. The retina is a thin, light-sensing layer at the back of the eye that turns light...
Read articleRetinal vasculitis means there is inflammation in the tiny blood vessels inside the retina, which is the light-sensitive layer at the back of the eye. When...
Read articleAn RPE tear is a sudden rip in the thin brown “support layer” under the retina called the retinal pigment epithelium (RPE). This layer normally sits...
Read articleThe retinal nerve fiber layer (RNFL) is the thin, outermost layer on the inside of the eye where the long cables (axons) of the retinal ganglion...
Read articleRetinal metastasis means cancer cells from somewhere else in the body have traveled through the bloodstream and settled inside the retina, the light-sensing layer at the...
Read articleLeukemic retinopathy is an eye problem that happens in people who have leukemia, which is a cancer of the blood and bone marrow. In leukemia, the...
Read articleLeukemia is a cancer of the blood and bone marrow. It changes how white blood cells, red blood cells, and platelets are made and how they...
Read articleThe retinal hemifield slide phenomenon happens when the right and left eyes can no longer keep the two halves of vision “locked together” at the midline....
Read articleRhegmatogenous retinal detachment is a serious eye condition where a break in the retina lets watery gel from the middle of the eye (called the vitreous)...
Read articleRetinal displacement means the thin nerve layer at the back of the eye (the retina) has shifted from its normal place, even a little, so the...
Read articleRetinal detachment means the retina—the thin, light-sensing layer that lines the back of the eye—has pulled away from the wall of the eye that normally nourishes...
Read articleVHL disease is an inherited condition that makes a person more likely to develop certain tumors and cysts in different parts of the body. These growths...
Read articleRetinal capillary hemangioblastoma is a benign (non-cancerous) but highly vascular (very blood-vessel-rich) growth that arises inside the retina, which is the light-sensing layer at the back...
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