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 articleProliferative diabetic retinopathy is an advanced eye problem caused by long-standing diabetes. High blood sugar damages tiny retinal blood vessels. Parts of the retina become starved...
Read articlePanophthalmitis is a very severe eye infection and inflammation. In this condition, almost every part of the eye is involved. The cornea, conjunctiva, anterior chamber, iris,...
Read articleCoral keratitis usually means toxic injury to the cornea from palytoxin, a powerful natural poison made by some zoanthid/soft corals (popular in home reef aquariums). The...
Read articlePalytoxin keratitis means the clear window at the front of your eye (the cornea) becomes damaged and inflamed after the eye touches palytoxin. Palytoxin is a...
Read articlePalinopsia means you keep seeing an image after the real object is gone. The picture may linger in place, follow or “trail” moving things, or pop...
Read articlePainful tic convulsif syndrome happens when two problems occur together on the same side of the face: trigeminal neuralgia (sudden electric-shock face pain) and hemifacial spasm...
Read articlePhotoablation means using a special laser to reshape or remove very thin layers from the clear front window of the eye (the cornea). Surgeons use a...
Read articlePachydrusen are small mounds of waste material that collect under the retinal pigment epithelium (RPE) in the back of the eye. They look yellow-white on photographs...
Read article“Pachy-” means thick. The choroid is the spongy, blood-vessel layer under your retina that feeds the retina oxygen and nutrients. In the pachychoroid spectrum, parts of...
Read articlePachychoroid neovasculopathy is an eye condition that happens in the macula, the tiny central area of the retina that gives sharp vision. In PNV, the choroid—the...
Read articleOxidative stress means the “rusting” or damage that happens inside living tissue when there are too many aggressive oxygen molecules, called reactive oxygen species (ROS), and...
Read articleOrbital xanthomas are yellow to yellow‑orange growths or swellings that develop around the eyes or inside the eye socket (the orbit). They form because special scavenger...
Read articleOrbital vasculitis means inflammation of the blood vessel walls inside the eye socket (the orbit). The orbit holds the eyeball, the eye muscles, the optic nerve,...
Read articleAn orbital varix is a group of abnormally enlarged, stretchy veins inside the eye socket (the orbit). A normal vein is a soft tube that carries...
Read articleAn orbital teratoma is a rare tumor that grows inside the eye socket (the orbit, the bony space that holds the eye). It is congenital, which...
Read articleOrbital melanoma is a cancer made from pigment-making cells called melanocytes that is found inside the eye socket (the orbit). The orbit is the bony space...
Read articleAn orbital mass is any abnormal lump, growth, or swelling inside the eye socket (the bony orbit). The orbit is a cone-shaped space in the skull...
Read articleOrbital Infarction Syndrome means that almost everything inside the orbit (the “eye socket”) suddenly does not get enough blood and oxygen and starts to die. In...
Read articleAn orbital granular cell tumor is a rare growth that starts from the support cells that wrap around nerves (called Schwann cells) and develops inside the...
Read articleAn orbital foreign body means that a piece of material that does not belong to the body has entered and remained inside the orbit, which is...
Read article
