Cystinosis is a rare inherited disease caused by mutations in the CTNS gene that prevents the normal removal of a small amino acid called cystine from inside ...

Cysticercosis of the eye is an infection where the larval stage of the pork tapeworm (Taenia solium), called Cysticercus cellulosae, lodges in or around the ...

Synophthalmia is an extremely rare and severe birth defect in which the two eyes are fused into one or are so closely set that they appear as a single eye—this ...

Synophthalmia (pronounced sin-off-THAL-mee-ah) is a very rare and severe birth defect in which the two developing eyes fail to separate and instead grow ...

Cyclopia (sometimes called cyclocephaly or synophthalmia) is the most extreme facial expression of a brain‐formation error known as alobar holoprosencephaly. ...

Glaucoma is a group of eye diseases that slowly damage the optic nerve, usually because of elevated pressure inside the eye (intraocular pressure, IOP). Over ...

A cyclodialysis cleft is an abnormal separation between the ciliary body and the scleral spur in the eye. The ciliary body normally attaches to the scleral ...

Cushing’s syndrome is the condition caused by having too much cortisol in the body over time. Cortisol is a stress hormone made by the adrenal glands; when its ...

Crystalline retinopathy is not one single disease. It is a family of rare eye problems in which tiny, shiny crystals build up inside the layers of the ...

Cryptophthalmos is a rare congenital eye condition where the eyelids fail to form properly, and skin is continuous over the eye, hiding the palpebral fissure ...

Cryptococcal choroiditis is an uncommon fungal infection in which Cryptococcus neoformans or C. gattii—yeast-like fungi usually found in bird droppings and in ...

Crunch Syndrome—also called the anti-VEGF crunch phenomenon—is a serious, sight-threatening complication that can appear days to weeks after an injection of an ...

Crossed Quadrant Homonymous Hemianopsia—sometimes nick-named the “checkerboard visual-field defect”—is an exceptionally rare pattern of visual-field loss in ...

Corneal collagen cross-linking (CXL) is a medical procedure used to strengthen the cornea, usually to slow or stop progressive thinning or bulging in ...

Crocodile shagreen of the cornea is a benign, usually harmless degenerative finding that gives the cornea a faint, polygonal, “crocodile skin” appearance. Most ...

Crocodile shagreen (also called crocodile shagreen of Vogt or simply crocodile shagreen of the cornea) is a harmless age-related change that makes the front ...

Craniosynostosis means that one or more of the flexible seams (called cranial sutures) in a baby’s skull close much earlier than they should. When the closure ...

Follicular dendritic cell sarcoma (FDCS) is a rare malignant tumor arising from follicular dendritic cells—specialized cells that reside in the germinal ...

Cranial neuritis means inflammation of one or more of the twelve cranial nerves that come directly out of the brain or brainstem. When a cranial nerve becomes ...

Cranial Nerve IV palsy—often called trochlear nerve palsy or superior-oblique muscle palsy—is a problem with the fourth cranial nerve, the tiny motor nerve ...