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 articleThe lacrimal gland sits in the outer-upper corner of each eye socket and makes the watery part of your tears. A pleomorphic adenoma of the lacrimal...
Read articlePlateau iris is a shape problem inside the front of the eye. The colored part of the eye (the iris) looks flat in the middle, but...
Read articleA pinguecula is a small, raised spot on the white part of the eye. The white part of the eye is called the sclera. The clear...
Read articlePigmented Paravenous Retinochoroidal Atrophy (PPRCA) is a rare eye condition. In this condition, clumps of black or brown pigment collect along the paths of the retinal...
Read articlePigment Dispersion Syndrome is an eye condition where tiny grains of natural color (called pigment) rub off the back of the iris, which is the colored...
Read articlePigmentary glaucoma is a type of open-angle glaucoma that happens when tiny particles of brown pigment rub off the back surface of your iris (the colored...
Read articlePigment epithelial detachment, or PED, happens when a very thin layer at the back of the eye, called the retinal pigment epithelium (RPE), lifts up from...
Read articleAstigmatism means the eye does not focus light evenly in all directions. One main direction (meridian) of the eye bends light a little more or a...
Read articlePhthisis bulbi means an eye has become shrunken, scarred, and permanently blind after severe damage or long-standing disease. It is usually irreversible. Care focuses on comfort...
Read articlePhotorefractive Intrastromal Cross-Linking, usually shortened to PiXL, is a non-incisional eye procedure that uses special eye drops (riboflavin, a form of vitamin B2) and a controlled...
Read articlePhotokeratitis is a painful, sudden sunburn of the clear front window of the eye, called the cornea. It happens when the cornea is exposed to too...
Read articlePhoto-oculodynia means your eyes feel real pain when exposed to ordinary light (for example, indoor light or daylight), even when the eye exam can look almost...
Read articlePACK-CXL is a light-based treatment used on the cornea (the clear front window of the eye) when there is a corneal infection (infectious keratitis). Doctors first...
Read articlePhlyctenular keratoconjunctivitis (PKC) is an eye condition where the body’s immune system overreacts to germs or germ-related proteins and creates a small inflamed bump on the...
Read articleMydriasis means the pupil is larger than normal. The pupil is the black hole in the center of the eye. It looks like a hole, but...
Read articleYour pupil is the black circle in the center of your eye. It is a round opening in your iris (the colored part). The pupil is...
Read articlePseudophacocele means that an artificial lens implant (an intraocular lens, or IOL) that was put inside the eye during cataract surgery has been pushed out of...
Read articleA phacocele is a rare eye injury where the natural lens of the eye gets pushed out of its normal position and ends up under the...
Read articlePhacoanaphylactic endophthalmitis is a rare kind of sterile (non-infectious) inflammation inside the eye that happens after lens proteins leak out of the natural lens because the...
Read articlePeters anomaly is a rare eye condition that a baby is born with. It affects the front part of the eye, which doctors call the “anterior...
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