The equine fundus. II: Normal anatomical variants and colobomata.

A wide range of fundic variants are encountered during routine ophthalmoscopic examination of visually normal horses, often causing the examiner difficulty in assessing their clinical significance. Many of these are anatomical variants having no significant effect on visual function, and lie within the limits of normality in the horse. This paper illustrates this range of variants and discusses their anatomical basis and physiological consequences. Colobomata are non-progressive discontinuities in the structure of the anatomic fundus, occasionally noted as incidental findings during ophthalmoscopy. This paper illustrates typical and atypical colobomata of the equine fundus, the latter occurring outside the embryonic optic fissure. The anatomical basis of these colobomata and their possible consequence on vision is discussed.