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 articleWernicke Encephalopathy (WE) is a sudden brain disorder caused by a lack of vitamin B1 (thiamine). Thiamine is a small nutrient your body cannot store in...
Read articleWeill-Marchesani Syndrome (WMS) is a rare, inherited connective-tissue condition that affects the eyes, the skeleton (bones and joints), and sometimes the heart. In everyday terms, people...
Read articleWallenberg syndrome happens when the side (lateral) part of the medulla—a small but vital area at the bottom of the brainstem—loses its blood supply, most often...
Read articleWaldenström Macroglobulinemia (WM) is a rare cancer of B-cells (a type of white blood cell). These cancer cells live mainly in the bone marrow and make...
Read articleWaldenström macroglobulinemia is a rare type of slow-growing blood cancer. It starts in B-lymphocytes (a type of white blood cell) inside the bone marrow. These B-cells...
Read articleWagner syndrome is a rare, inherited eye condition that mainly affects the vitreous (the clear gel that fills the eye) and the retina (the light-sensitive layer...
Read articleA Vossius ring is a round, brown-black circle that appears on the front surface of the eye’s natural lens (the anterior lens capsule) after blunt trauma...
Read articleA vortex vein varix is a localized, balloon-like widening of a vortex vein, which is one of the large choroidal drainage veins inside the eye. The...
Read articleVon Hippel–Lindau (VHL) syndrome is an inherited condition that raises the lifetime risk of developing multiple tumors and cysts in different organs. These growths often include...
Read articleVogt’s striae are very fine, straight, vertical lines that an eye doctor can see inside the clear front window of your eye (the cornea) when you...
Read articleVogt–Koyanagi–Harada (VKH) disease is an autoimmune condition. “Autoimmune” means the body’s defense system gets confused and attacks its own cells. In VKH, the immune system mainly...
Read articleVitreous Wick Syndrome is a problem that happens when strands of the eye’s vitreous (the clear, gel-like substance that fills the back of the eye) slip...
Read articleVitreous metastasis means cancer cells that started somewhere else in the body have traveled through the bloodstream and reached the vitreous (the clear gel that fills...
Read articleVitreous hemorrhage means bleeding into the vitreous, the clear gel that fills most of the inside of the eye between the lens at the front and...
Read articleA vitreous cyst is a small, round or oval sac filled with fluid that floats inside the vitreous (the clear gel that fills the back of...
Read articleVitreopapillary Traction Syndrome is a condition where the vitreous—the clear gel that fills the back of the eye—pulls abnormally on the optic nerve head, also called...
Read articleVitreomacular Traction Syndrome means the clear gel that fills the eye—the vitreous—is pulling on the macula, which is the sharp-seeing center of the retina. The macula...
Read articleVisual vertigo / visually-induced dizziness means you feel dizzy, off-balance, or motion-sick mainly when your eyes see a lot of motion or busy patterns. Your inner...
Read articleVisual Variant of Alzheimer’s Disease is a form of Alzheimer’s that mainly damages the back parts of the brain (the occipital, parietal, and occipito-temporal lobes). These...
Read articleVisual symptoms of Parkinson’s disease are problems with how the eyes move, how comfortable the eyes feel, and how the brain handles visual information. They can...
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