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 articleTeleophthalmology means “eye care at a distance.” It uses phones, secure messaging, photos, videos, and connected devices to help eye doctors examine, diagnose, treat, and follow...
Read articleEpicanthus is a skin fold at the inner corner of the eye. This fold runs from the upper eyelid (and sometimes the lower eyelid) toward the...
Read articleTelecanthus means the inner corners of the eyelids (the medial canthi) are farther apart than usual, even though the eyeballs and the bony eye sockets are...
Read articleTele-glaucoma is glaucoma care that happens at a distance with the help of digital tools. It uses cameras, scanners, portable eye devices, and secure internet connections...
Read articleThe tegmen is the thin roof bone that separates the air spaces of the middle ear and mastoid from the brain. The part over the middle...
Read articleTear trough deformity is a hollow or groove that forms between the lower eyelid and the upper cheek. It can make the eyes look tired, sunken,...
Read articleTattoo-associated uveitis is inflammation inside the eye that happens in a person who has a tattoo on the skin. The uvea is the middle layer of...
Read articleTanzanian Endemic Optic Neuropathy, often shortened to TEON, is a disease that damages the optic nerves in both eyes. The optic nerves are like thick electric...
Read article“Tadpole pupil” is a rare, short-lasting change in the shape of one pupil. The round pupil suddenly stretches or pulls at one edge. The pupil looks...
Read articleTacrolimus optic neuropathy is a rare eye nerve problem linked to the medicine tacrolimus. Tacrolimus is a strong anti-rejection drug used after organ and stem-cell transplants...
Read articleSyphilitic uveitis is eye inflammation caused by the sexually transmitted infection syphilis, which is due to a spiral-shaped bacterium called Treponema pallidum. The bacterium can reach...
Read articleSyphilitic keratitis means inflammation of the clear front window of the eye (the cornea) that is caused by the infection called syphilis. Syphilis is an infection...
Read articleSynovial sarcoma is a rare cancer that starts in soft tissues. It most often grows near large joints in the arms or legs of teenagers and...
Read articleSynechiae means “sticking together.” In the eye, it means parts that should glide smoothly now stick together and will not separate easily. The most common kind...
Read articleSynchysis scintillans is a rare eye condition where tiny cholesterol crystals float inside the jelly of the eye. The eye jelly is called the vitreous. When...
Read articleSympathetic ophthalmia is a rare eye disease. It happens when one eye is injured or operated on, and the body’s immune system later starts attacking both...
Read articleSymmetrical Drug-Related Intertriginous and Flexural Exanthema (SDRIFE)—sometimes called “drug-induced baboon syndrome”. SDRIFE is a specific kind of drug rash. It shows up after you take a...
Read articleSymblepharon means the inner skin of the eyelid sticks to the white surface of the eye. The inner skin of the eyelid is called the palpebral...
Read articleAcute febrile neutrophilic dermatosis is a skin disease. Doctors also call it Sweet syndrome. “Acute” means it starts suddenly. “Febrile” means it comes with fever. “Neutrophilic”...
Read articleSweet syndrome is a skin disease in which the body’s immune system suddenly sends many neutrophils, which are a type of white blood cell, into the...
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