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 articleOcular neuropathic pain means eye pain that mainly comes from a problem in the nerves that carry pain signals from the eye and around the eye...
Read articleOcular neuromyotonia (ONM) is a rare problem with the nerves that move the eyes. In ONM, one or more eye muscles suddenly “lock” or spasm for...
Read articleWyburn-Mason Syndrome (WMS) is a very rare condition present from birth in which some blood vessels grow in an unusual way. Instead of a normal tiny...
Read articleSubclavian Steal Syndrome (SSS) is a blood-flow problem. It happens when one of the big arteries that supplies blood to your arm—the subclavian artery—becomes narrow (stenosed)...
Read articlePolychondritis—usually called relapsing polychondritis (RP)—is a rare disease where your immune system mistakenly attacks your own cartilage. Cartilage is the strong, flexible tissue that gives shape...
Read articleA myeloma protein (often written as M-protein, monoclonal protein, paraprotein, or M-spike) is a single, abnormal antibody made in large amounts by a clone of plasma...
Read articleEndocrinopathy means any health problem that starts in the body’s hormone system. Your hormone system is called the endocrine system. It includes small but powerful glands—like...
Read articleAn enlarged ovary means one or both ovaries are bigger than usual. It is not a single disease—it is a sign that can happen for many...
Read articleUteromegaly means the uterus is larger than normal. The uterus is a hollow, muscular organ in the pelvis that normally sits behind the bladder and in...
Read articleUterine megaly (also called uteromegaly or an enlarged uterus) means the uterus is bigger than expected for a person’s age, body size, and life stage. The...
Read articleProstatomegaly means the prostate gland is bigger than usual. Doctors also call it an “enlarged prostate.” The word comes from “prostate” (the male gland below the...
Read articleThyromegaly means the thyroid gland is bigger than normal. The thyroid is a small, butterfly-shaped gland that sits in the front of your lower neck. It...
Read articleNephromegaly means the kidneys are bigger than normal for a person’s age and body size. Doctors usually judge kidney size with imaging, especially ultrasound. In healthy...
Read articleCardiomegaly means “an enlarged heart.” It is a finding, not a final diagnosis. In simple words, the heart looks bigger than normal, or one or more...
Read articleSplenomegaly means the spleen is bigger than normal. The spleen sits high on the left side of your belly, just under the ribs. In healthy adults...
Read articleOrganomegaly means an internal organ is bigger than normal. The word comes from “organo” (organ) and “megaly” (big). Any organ can become large. The most common...
Read article“Phakomatoses” (also called neurocutaneous syndromes) are conditions that affect the skin, the brain and nerves, and often other organs. The word comes from an old Greek...
Read articleMoyamoya disease is a rare brain blood vessel problem where the main arteries that carry blood into the deep parts of the brain slowly become tight...
Read articleThis phrase means all the eye problems and eye changes that can happen because of isotretinoin. Isotretinoin is a vitamin A–like drug (a retinoid) that shrinks...
Read articleHidradenitis suppurativa (HS) is a long-lasting skin disease. It causes painful lumps, boils, and “tunnels” under the skin. These bumps happen where skin rubs together, like...
Read article
