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 articleLockwood’s Ligament–Related Disorder (LLRD) means the eye’s natural “hammock” support under the eyeball and the nearby lower-eyelid support tissues have become loose, stretched, scarred, or injured....
Read articleZonular disease means a problem with the tiny fibers that hold the natural lens of the eye in place. These fibers are called lens zonules or...
Read articleThe suspensory ligament of the eye is a ring of very fine fibers that hold the clear natural lens in the middle of the eye. These...
Read articleSurgically-Induced Necrotizing Scleritis, or SINS, is a very severe inflammation that eats away the white wall of the eye called the sclera, and it happens after...
Read articleSuprachoroidal hemorrhage is bleeding that happens inside the eye in a very specific space. The eye wall has several layers. One layer is the sclera, which...
Read articleThe suprachoroidal space is a potential space between the choroid and the sclera. When fluid or blood collects here, the choroid lifts away from the sclera....
Read articleThe superior transverse scapular ligament (STSL) is a small, flat band of tissue at the top of the shoulder blade (scapula). It stretches over a natural...
Read articleSuperior Segmental Optic Nerve Hypoplasia (SSONH)—sometimes nicknamed the “topless optic disc”—is a congenital (present at birth) optic nerve anomaly in which the upper (superior) portion of...
Read articleSuperior Orbital Fissure Syndrome, or SOFS, is a group of nerve and vein problems that happen in a narrow tunnel behind the eye called the superior...
Read articleSuperior ophthalmic vein thrombosis is a clot in a main vein that drains blood from the eye into the cavernous sinus inside the skull. It is...
Read articleA cavernous sinus–dural fistula (often called an “indirect” carotid-cavernous fistula) is an abnormal shortcut between small artery branches in the skull base and the cavernous sinus,...
Read article“Superior Ophthalmic Vein Cannulation Fistulas” isn’t the name of a disease. It mixes a treatment approach (“superior ophthalmic vein cannulation,” which is a way to reach...
Read articleSuperior Oblique Myokymia is a rare condition where one eye’s superior oblique muscle twitches in very small, very fast bursts. People feel brief spells of “shimmering”...
Read articleSuperior Limbic Keratoconjunctivitis—often shortened to SLK—is a long-lasting, on-and-off eye surface problem that mainly irritates the upper part of the eye where the white part (conjunctiva),...
Read articleSunrise Syndrome is a complication after cataract surgery in which the artificial lens (intraocular lens, or IOL) slides or sits too high in the eye (a...
Read article“Unilateral neuralgiform headache” is a group name for very short, very sharp, one-sided head pain attacks. The pain is strictly on one side of the head...
Read articleSUNCT is a rare headache condition. The name tells you the main features: Short-lasting, Unilateral (one-sided), Neuralgiform (sharp, electric-like) headache attacks with Conjunctival injection (the white...
Read articleA subperiosteal hematoma is a pocket of blood that gathers under the periosteum. The periosteum is a thin, tough sheet that covers the outside of every...
Read articleSubepithelial Mucinous Corneal Dystrophy (SMCD) is an extremely rare inherited eye condition that mainly affects the front clear window of the eye (the cornea). “Subepithelial” means...
Read articleSubepidermal calcinosis means tiny deposits of calcium salts just under the outer layer of your skin. Doctors often call the classic form a subepidermal calcified nodule...
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