(From caligo, to be dark). A growing darkness of the eye, or dimness of the sight, from a manifest cause; as in cases of the cataract, etc. Dr. Cullen places this genus of disease in the class locales, and order dysaesthesiae. He defines it to be sight diminished, or wholly abolished; from a dark barrier between the object and the retina, in the eye itself, or in the eye lid. He also enumerates five species; viz.
1. Caligo Lento; the glaucoma Woolhousi, maitre Jean St. Yves; this he denominated the cataract, and Sauvages calls it the true cataract, it is caused by a thickening of the coats of the crystalline lens. See Cataracta.
3. Caligo pupillae, from obstruction in the pupil.
4. Caligo humorum, glaucoma Vogelii, from a fault in the humours of the eye.
5. Caligo palpebrarum, from a disorder in the eye lids. See Cullen's Nosology, edit. 3.