The accomodation apparatus of the eye in Accipitriformes and Strigiformes - a comparative morphological study Reese, S. u. S. Lang 2. In corneal accomodation the contraction of the anterior ciliary muscle pulls the corneal margin inwards. In lenticular accomodation the contraction of the posterior ciliary muscle pulls the ciliary body inwards and squeezes the lens. Accordingly there is a large variance in the range of accomodation between different bird species. The ciliary body, particulary the different parts of the ciliary muscle, were examined by light microscopy.
Results indicate distinct structural differences in the ciliary muscle.
In Accipitriformes the anterior part of the ciliary muscle is well developed and approximately a little bit larger than the posterior part. In contrast, in Strigiformes the anterior ciliary muscle is conspicuously thick, however, the posterior part of the muscle is underdeveloped. In conclusion in Accipitriformes accomodation is corneal and lenticular while in Strigiformes it is primarily corneal. Form and function in birds Vol 3.