ögonytan

Ögonytan, sometimes written ögonytan, is a term used in ophthalmology to denote the outer surface of the eyeball. It comprises the corneal and scleral surfaces and the overlying conjunctiva and tear film, together with the lid margins that interact with the surface. The term is mainly used in Nordic medical literature; in English, ocular surface is more common.

Originating from Swedish, ögon means eye and ytan means surface; first appears in late 19th century in anatomical descriptions. It is sometimes employed to emphasize the functional surface rather than the interior structures of the eye.

Anatomically, the ocular surface includes the corneal epithelium, tear film, conjunctival epithelium, and the anterior scleral surface, all collaborating with the lacrimal apparatus and eyelids to maintain smooth refractive interface and protection from pathogens. The surface is maintained by tear production, blinking, and mucins.

Clinical relevance lies in ocular surface disease, including dry eye syndrome, conjunctival inflammation, and exposure keratopathy. Evaluation uses fluorescein and lissamine green staining, tear film breakup time, Schirmer test, and impression cytology. Management aims to restore tear film stability and surface health with artificial tears, anti-inflammatory agents, punctal plugs, and eyelid hygiene.

See also: ocular surface, cornea, conjunctiva, sclera, tear film, eyelids.