Unilateral microphthalmia or anophthalmia in eight pythons (Pythonidae)
Mari-Ann O Da Silva1, Mads F Bertelsen, Tobias Wang
1Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, DK-1870, Frederiksberg, Denmark; Department of Neuroscience and Pharmacology, Eye Pathology Institute, University of Copenhagen, Copenhagen, Denmark.
Objective:
To provide morphological descriptions of microphthalmia or anophthalmia in eight pythons using microcomputerized tomography (μCT), magnetic resonance imaging (MRI), and histopathology.
Animals Studied:
Seven Burmese pythons (Python bivittatus) and one ball python (P. regius) with clinically normal right eyes and an abnormal or missing left eye.
Procedure:
At the time of euthanasia, four of the eight snakes underwent necropsy. Hereafter, the heads of two Burmese pythons and one ball python were examined using μCT, and another Burmese python was subjected to MRI. Following these procedures, the heads of these four pythons along with the heads of an additional three Burmese pythons were prepared for histology.
Results:
All eight snakes had left ocular openings seen as dermal invaginations between 0.2 and 2.0 mm in diameter. They also had varying degrees of malformations of the orbital bones and a limited presence of nervous, glandular, and muscle tissue in the posterior orbit. Two individuals had small but identifiable eyes. Furthermore, remnants of the pigmented embryonic framework of the hyaloid vessels were found in the anophthalmic snakes. Necropsies revealed no other macroscopic anomalies.
Conclusions:
Eight pythons with unilateral left-sided microphthalmia or anophthalmia had one normal eye and a left orbit with malformed or incompletely developed ocular structures along with remnants of fetal structures. These cases lend further information to a condition that is often seen in snakes, but infrequently described.
