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 articleThis phrase means what to do before an eye specialist (ophthalmologist) sees the patient. It includes the very first steps at home, in the field, in...
Read articlePrader–Willi syndrome is a genetic condition that affects many parts of the body. In the first months of life, most babies with PWS have very low...
Read articlePourfour du Petit syndrome is a rare problem of the sympathetic nerves to the eye and face. The key signs are a large pupil (mydriasis), upper...
Read articlePostoperative decompensated strabismus means a hidden eye misalignment (a “phoria”) becomes obvious (a “tropia”) after eye surgery, so the two eyes no longer point to the...
Read articlePosterior vitreous detachment (PVD) is a very common eye change that happens as we get older. Inside the eye there is a clear gel called the...
Read articlePosterior Polymorphous Corneal Dystrophy (PPCD) is a rare, usually inherited eye condition that affects the innermost layer of the cornea (the clear front window of the...
Read articleA posterior polar cataract is a cloudy spot that sits right in the center of the back surface of your eye’s natural lens. Because it is...
Read articlePosterior keratoconus is a rare eye condition that affects the back surface of the cornea. The cornea is the clear window at the front of your...
Read articlePosterior Ischemic Optic Neuropathy (PION) means the back part of the optic nerve does not get enough blood and oxygen for a period of time. The...
Read articleThe posterior capsule is an ultra-thin, transparent membrane that hugs the back surface of the eye’s natural lens. Think of it as the back wall of...
Read articlePosterior Amorphous Corneal Dystrophy is a rare eye condition that changes the very back part of the cornea. The cornea is the clear, curved “window” at...
Read articlePost-traumatic endophthalmitis is a severe eye infection that happens after an eye injury. “Post-traumatic” means it follows trauma, such as a cut, puncture, blast, or any...
Read articlePost-streptococcal uveitis is an eye inflammation that shows up after a recent streptococcal infection, most often after a sore throat, tonsillitis, or a skin infection caused...
Read articlePost-LASIK epithelial ingrowth means that some of the surface skin cells of the cornea (called epithelial cells) slide under the LASIK flap and start growing in...
Read articlePost-Injection Endophthalmitis is a severe infection inside the eye that happens after a needle injection into the eye (for example, an intravitreal anti-VEGF, steroid, or antibiotic...
Read article“Post capsular haze” (doctors usually say posterior capsular opacification or PCO) is a common problem that can happen months or years after cataract surgery.During cataract surgery,...
Read articlePressurized eye goggles are special, airtight goggles that gently change the air pressure around your eyes for a short time. When the pressure inside the goggles...
Read articlePolypoidal choroidal vasculopathy is a disease that affects the layer of blood vessels under the retina, called the choroid. In PCV, a network of new vessels...
Read articlePneumatic retinopexy is an eye procedure that uses a small gas bubble to press the retina back into place so it can seal and heal. Doctors...
Read articlePlus–minus lid syndrome is a rare eye–lid problem where one upper eyelid droops (ptosis) while the other upper eyelid pulls up too far (retraction). Both changes...
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