Ocular biometry of snakes of the species Python bivittatus kept in captivity

Abstract

During embryological development, the eyelids of snakes fuse and no longer open like in mammals. They become transparent, thus forming spectacles, a transparent structure that covers the eyes. The primary function of these spectacles is to provide a physical barrier to protect the eyes without eyelids. This study aimed to evaluate the ocular biometry of Python bivittatus snakes. Ocular ultrasound examinations were performed on four individuals using the Logic E ultrasound device (GE, United States) with a 10-22 MHz linear probe. Conduction gel was used to make transducer contact with the cornea in these snakes. Images were obtained to evaluate the following measurements: axial length of the eyeball, anterior chamber depth, lens thickness, and vitreous depth. These measurements of intraocular structures were, respectively: 0.05 ± 0.02 cm for corneal thickness in the right eye and 0.04 ± 0.007 cm in the left eye; 0.11 ± 0.04 cm for anterior chamber depth in the right and left eyes; 0.36 ± 0.07 cm for the lens thickness in the right eye and 0.39 ± 0.05 cm in the left eye; 0.35 ± 0.05 for the depth of the vitreous chamber in the right eye and 0.31 ± 0.02 cm in the left eye; and 0.85 ± 0.18 cm for the length of the globe in the axial plane in the right eye and 0.85 ± 0.14 cm in the left eye. Knowledge of snakes’ anatomical and ophthalmological parameters is scarce, and the incidence of eye diseases is still little known, making further studies necessary.