Horner syndrome is a condition that happens when the nerve pathway that controls certain eye and facial functions is damaged. This pathway is called the ...

Homocystinuria (pronounced “home-oh-sis-tin-YOOR-ee-uh”) is a genetic disorder. It happens when one of the enzymes needed to break down homocysteine—an ...

HLA-B27-Associated Acute Anterior Uveitis (HLA-B27 AAU) is a sudden inflammation of the front part of the eye—the iris (colored part) and ciliary body (just ...

HIV-associated facial lipoatrophy is a condition in which people living with HIV lose fat in their faces. This can make cheeks look hollow, temples appear ...

Central Serous Chorioretinopathy—often shortened to CSCR or just “central serous”—is an eye disease in which clear fluid leaks out of the small blood vessels ...

Central Retinal Vein Occlusion means that the single large vein that drains blood out of the retina – the light‑sensitive “film” at the back of your eye – has ...

Central neurocytoma (CN) is a rare, slow‑growing brain tumour that starts from immature nerve‑like cells (neurons) inside the fluid‑filled cavities of the ...

Your fovea is the tiny, bowl-shaped pit in the very center of the macula—the macula being the central patch of retina that lets you read, drive, and recognize ...

Central Cloudy Dystrophy of François is a very rare stromal corneal dystrophy first described in 1955. In this condition, the central part of each cornea ...

Central Areolar Choroidal Dystrophy is a rare, inherited eye condition that slowly erodes the very heart of your central retina (the macula). In CACD, the ...

Cavernous Sinus Syndrome (CSS) is a collection of signs and symptoms that appear when the structures running through, or lying next to, the cavernous sinus ...

A cataract is any cloudiness or opacity inside the eye’s natural lens. In children the condition is especially serious because the developing brain relies on ...

Cat Scratch Disease (often nick‑named “cat‑scratch fever”) is an infection caused by the bacterium Bartonella henselae. People usually catch it when a kitten ...

A caruncular dermoid cyst is a small, benign (non‑cancerous) pocket of tissue that grows in the lacrimal caruncle—the tiny pink nodule you see at the inner ...

Transient Perivascular Inflammation of the Carotid Artery—usually shortened to TIPIC syndrome—is a short‑lived but intensely painful swelling around one side ...

Carotidynia—sometimes called Fay’s syndrome or TIPIC syndrome (Transient Perivascular Inflammation of the Carotid artery)—is an uncommon cause of one‑sided ...

A carotid cavernous fistula (CCF) is an abnormal “shortcut” channel that opens between one of the main arteries carrying blood to the brain—the internal or ...

Capsular Bag Distension Syndrome, also called capsular block syndrome, is a rare but important complication that can appear after cataract surgery when an ...

CAPOS syndrome is a very rare, inherited neurological condition first described in 1996 and traced to a single spelling mistake (missense variant Glu818Lys and ...

Capillary hemangioma—often called an infantile hemangioma, strawberry birth‑mark, or benign vascular tumor—is the most common tumor of infancy. Although it ...