Coronæ round a Light produced by a Peculiar Structure in the Eye

Abstract

FOR some years past I have been aware that a bright light on a dark background appeared to be surrounded by faint coloured rings, and that these rings were due to something in the eye itself. But I gave them little attention, for I imagined they were formed in the same way as the coronae seen when the sun or moon is covered by a thin cloud; opaque particles in the cornea, or little elevations or depressions of its surface, playing the part of the drops of water in the cloud. This is the view taken in Verdet's great work on the wave-theory of light. “Les cercles irises, qu'a la suite de certaines inflammations de la conjonctive on apercoit autour des corps lumineux, se rattachent a la meme cause que les couronnes; ces apparences sont dues a l'existence de granulations tre -petites et sensiblement egales dans la portion de la conjonctive qui se trouve en avant de la cornee transparente” (Verdet, “Lecons d'Optique Physique,” § 79). I have lately discovered, however, that the phenomenon in my own case must be due to quite a different cause.