It is recommended that an ophthalmic examination is conducted as part of the annual physical examination of captive elephants.6 The ability to perform an ophthalmic examination in elephants is dependent on their level of training; hence lack of patient cooperation may create safety issues for handlers.6,8 Transpalpebral ultrasonography is regarded as a rapid and non-invasive imaging modality and would therefore prove useful in the examination of the live unsedated elephant.1,3,5,7 As there is no published work related to the use of ocular ultrasonography in elephants, the objective of this study was to describe the normal ultrasonographic appearance and measurements of the African elephant eye. This knowledge could then serve as a base for clinical ocular ultrasonographic examinations, where pathology may have caused alterations in the appearance and structural dimensions of the globe and intraocular structures.2,4,5
Six African elephants from the United Kingdom and Germany had bilateral transpalpebral ultrasound scans performed. Five females and one male with a mean age of 14.67±0.82 years (mean ± standard deviation) were included in the study population. Animals within the study group were maintained in free contact management systems. Ultrasound examinations were performed with animals in lateral recumbency, in a stretched position or standing. Continuous flow of low-pressure water was used as the contact medium between the ultrasound transducer (4–7 MHz broadband curvilinear) and the eyelid skin. Ocular biometry measurements were taken from images obtained by scanning through both the upper and lower eyelids.
Mean biometry measurements recorded for adult African elephants (n=6) were axial length 3.37±0.09 cm, equatorial diameter 3.80±0.24 cm, corneal thickness 0.17±0.03 cm, anterior segment depth 0.45±0.05 cm, lens diameter 1.99±0.25 cm, lens thickness 0.98±0.10 cm and posterior segment depth 1.75±0.10 cm. The ultrasonographic appearance of the globe and intraocular structures of the African elephant eye is similar to that in other species.2,4,5
Transpalpebral ultrasonography was found to be a useful imaging modality for the rapid and non-invasive assessment of the African elephant eye. Chemical restraint and local/topical anesthesia were not required to perform ocular ultrasonography and images of diagnostic quality were produced from all animals despite variable levels of training and handling. In summary, transpalpebral ultrasonography is a valuable imaging technique to produce useful information regarding the health of the globe and intraocular structures without the need for chemical restraint.
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