Ophthalmic Parameters of Healthy Captive Blue-Tongued Skinks (Tiliqua scincoides)

Abstract

Normal ophthalmic parameters of the blue-tongued skink (Tiliqua scincoides), one of the largest members of the skink family of lizards, have yet to be evaluated. The objective of this study was to establish baseline ophthalmic parameters for a captive population of 12 healthy, one year old, blue-tongued skinks. Ophthalmic examination, corneal touch threshold, tear production including phenol red thread test (PRTT) and modified Schirmer tear test-2 (mSTT-2), horizontal palpebral fissure length (HPFL), rebound tonometry (TONOVET and TONOVET Plus), and bacterial and fungal culture were performed. The blue-tongued skinks were all amenable to ocular diagnostic testing. Corneal touch threshold (mean ± SD) was 5.48 ± 0.81 cm. PRTT (mean ± SD) was 9.17 ± 6.62 mm/15 seconds. mSTT-2 (mean ± SD) was 2.54 ± 2.72 mm/60 seconds. HPFL (mean ± SD) was 6.96 ± 0.62 mm and was positively correlated with body weight. Intraocular pressure (IOP) assessed using TONOVET (mean ± SD) was 8.43± 1.51 mmHg, while IOP assessed using TONOVET Plus (mean ± SD) was 12.39± 1.54 mmHg. Differences in TONOVET and TONOVET Plus tonometry values were statistically significant (P<0.0001) and TONOVET values positively correlated with body weight. The most common bacterial species identified were Staphylococcus xylosus (10/12) and Staphylococcus sciuri (8/12). Fungal cultures were all negative. One animal had superficial corneal ulceration which resolved with treatment. Ophthalmic examination and testing is readily performed in blue-tongued skinks. These parameters may be useful for ocular assessment of this species in a clinical setting.