Ophthalmic examination, biometry, and histologic findings in captive inland bearded dragons (Pogona vitticeps)

To report ophthalmic examination, biometry, phenol red thread test (PRTT), intraocular pressure (IOP), and histologic findings from a private collection of inland bearded dragons (Pogona vitticeps).

Fourteen inland bearded dragons.

Complete ophthalmic examinations were performed on all animals, including slit-lamp biomicroscopy, indirect ophthalmoscopy, fluorescein stain, phenol red thread test, and rebound tonometry. B-mode ultrasonography was used to measure anterior chamber depth, axial lens thickness, vitreal chamber depth, and axial globe length. Horizontal corneal diameter was estimated using ImageJ software. Histologic assessment was obtained for one of the bearded dragons that died following the study period.

The median PRTT value was 7.27 mm/15 seconds. Mean IOP was 6.29 ± 1.60 mm Hg and 2.14 ± 1.37 mm Hg using the dog and undefined calibration settings, respectively. Median axial globe length was 11.75 mm. Mean anterior chamber depth and mean lens thickness were 2.06 ± 0.35 mm and 3.38 ± 0.45 mm, respectively. Median vitreal chamber depth was 6.79 mm. Mean horizontal corneal diameter was 5.138 ± 0.346 mm. Two distinct ocular phenotypes were observed, with two of the bearded dragons having corneal globosa, deep anterior chambers, and tufts of iridal vessels and fibrillar material extending into the anterior chamber.

The ultrasound biometry, PRTT, and rebound tonometry results may serve as a guideline for ophthalmic parameters in healthy bearded dragons. Examination and testing of greater numbers of animals are necessary to establish true reference ranges and determine if the observed ocular phenotypes represent normal variants or pathologic changes.