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 articleVisual snow is a neurological visual phenomenon where you see countless tiny, flickering dots—like “TV static”—across your entire field of view, all the time, with your...
Read articleVisual neglect—often called hemispatial neglect or simply neglect—is a problem of attention and awareness, not a problem of eyesight itself. A person with visual neglect acts...
Read articleVici syndrome is a very rare genetic condition that starts early in life and affects many organs at the same time. The condition is usually caused...
Read articleVestibular disease rehabilitation is a therapeutic program that uses specific exercises and education to retrain how your balance system works. Your balance system includes your inner...
Read articleVertical gaze palsy means a person cannot move both eyes normally up or down on command. The problem is not in the eyeball muscles themselves—it is...
Read articleVertebrobasilar Insufficiency (VBI) is reduced blood flow to the back of the brain that can cause dizziness, imbalance, double vision, slurred speech, swallowing problems, and fainting....
Read articleVernal keratoconjunctivitis is a long-lasting (chronic), allergy-type inflammation of the front surface of the eye and the inner side of the eyelids. It mostly affects children...
Read articleThe vasculature of the orbit means all blood vessels that bring blood to and take blood away from the tissues inside the eye socket. This includes...
Read articleVaricella Zoster Virus (VZV) is the virus that causes chickenpox the first time you catch it and shingles when it wakes up again later in life....
Read articleVaricella Zoster Virus (VZV) stromal keratitis is inflammation and injury in the middle layer of the cornea (the clear front window of the eye) caused by...
Read articleValsalva retinopathy is a sudden bleed in front of the retina (a preretinal hemorrhage) that happens after an intense, brief strain—like a hard cough, vomiting, lifting...
Read articleUveitis–Glaucoma–Hyphema (UGH) syndrome is a problem that can happen after cataract surgery when an artificial lens or another device inside the eye rubs against the iris...
Read articleHyphema means blood inside the front chamber of the eye (the space between the cornea and the iris). The blood comes from tiny torn blood vessels...
Read articleUveitis masquerade syndromes are eye problems that look like uveitis (inflammation inside the eye) but are not true autoimmune uveitis. In other words, the eye shows...
Read articleUveitic cataract is a cataract (a clouding of the eye’s natural lens) that develops because of uveitis, which is inflammation inside the eye. The eye’s inner...
Read articleUveitis is inflammation inside the eye, focused on a layer called the uvea. The uvea is the eye’s middle coat and includes the iris (the colored...
Read articleUveitic glaucoma is high pressure inside the eye that happens in a person who has uveitis (inflammation inside the eye). The uvea is the “middle coat”...
Read articleA hypermature cataract is the end stage of a cataract. A cataract means the natural lens inside the eye has turned cloudy. In early stages, only...
Read articleUveal pseudomelanoma means a spot or mass in the eye that looks like a uveal melanoma (a true eye cancer) but actually isn’t cancer. “Uveal” refers...
Read articleUveal Effusion Syndrome (UES) is a rare eye condition where fluid collects in the potential space around the uveal tissues—the choroid, the ciliary body, and sometimes...
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