Background: The aim of this study was to assess similarities and differences between the trout eye and the human eye.
Materials and methods: Gross and microscopic examinations of the formalin-fixed eyes of each five trout and human eyes (donor eyes not suitable for keratoplastic) were carried out.
Results: Compared to the human eye, the trout showed a flattening of the anterior-posterior axis, and cartilage-stabilized sclera. The peripheral cornea was much thicker than the central, had a multilayered thick epithelium, a distinct Bowman layer, and an implied Descement membrane. A ring-shaped ligament filled up the angle of the anterior chamber and linked the iris to the cornea. The lens showed a spherical aspect with a thick capsule and missing zonular fibres, however, a suspensory ligament of a superior part of the lens was present. Ventrally, at the end of the falciform process, a small, pigmented structure was in contact with the lens. The retina was similarly differentiated, but the choroid showed special structures like choroidal gland, falciform process and the argentea compared to the human eye.
Conclusions: Great variations between the ocular anatomy of the trout and the human exist. However, the retina of the trout is fully differentiated and remarkably similar to that of human eyes.