Histoanatomical study of the lens and ciliary body in ostrich eye.

In the present study, the lenses and ciliary bodies of 20 ostrich eyes were studied macroscopically and microscopically. The histological slides were studied after staining by hematoxylin and eosin, Verhoeff, Van Gieson, and periodic acid-Schiff (PAS). Posterior surface of lens was more convex than its anterior surface. The average lens diameter and thickness were respectively measured as 1.43 ± 0.00 and 0.85 ± 0.00 cm. The average ciliary body thickness was measured as 1.48 ± 0.01 cm. In addition, the ciliary body was seen annular with mean horizontal and vertical external diameters as 4.80 ± 0.07 and 4.36 ± 0.06 cm, respectively. The retina is extended on ciliary body in this bird. The number of ciliary body processes was about 120. The epithelium of lens was cuboidal and the lens capsule had intense positive PAS reaction. Also, the anterior surface of capsule was thicker than its posterior surface. The lens fibers in the central part were thicker than other parts. Elastic and collagen fibers were not observed in the lens. The epithelium of ciliary processes had two layers; superficial cuboidal non-pigmented layer, and deep heavily pigmented layer. The ciliary body was supported by a hyaline cartilage. In addition to the smooth muscle fibers, many isolated skeletal muscle fibers were also seen in ciliary body. In conclusion, the lens and ciliary body of ostrich were similar to other birds, although there were little differences in anatomical dimensions and histological characteristics.