Determination of Ophthalmic Parameters and Ocular Morphology in Ring-Necked Parakeets (Psittacula krameri)

To determine normal ophthalmic test values and to describe the ocular morphology of ring-necked parakeets (Psittacula krameri).

33 captive birds were examined, although not all tests were conducted on each bird. The tests included endodontic absorbent paper point tear test (EAPPTT), intraocular pressure (IOP), corneal touch threshold (CTT), central corneal thickness (CCT), palpebral and corneal diameters, ocular ultrasonography, and corneoconjunctival microbiota. The iris coloration of seven young parakeets was evaluated, and two macerated skulls were described.

Normal values obtained were: EAPPTT: 7.57 ± 1.95 mm/min; IOP: 12.47 ± 1.51 mmHg; CTT: 2.46 ± 0.5 mm; CCT: 0.12 ± 0.006 mm; palpebral diameter: 8.04 ± 0.49 mm,; corneal diameter: 6.41 ± 0.49 mm. In ocular ultrasonography, the dimensions in the sagittal plane were: axial globe length (AGL): 0.94 ± 0.02 cm; vitreous chamber depth (VCD): 0.47 ± 0.02 cm; lens axial length (LAL): 0.32 ± 0.01 cm; anterior chamber depth (ACD): 0.1 ± 0.01 cm; pecten width (PW): 0.12 ± 0.02 cm, and pecten length (PL): 0.42 ± 0.04 cm. In the dorsal plane: AGL: 0.93 ± 0.03 cm; VCD: 0.47 ± 0.02 cm; LAL: 0.32 ± 0.03 cm; ACD: 0.1 ± 0.01 cm; PW: 0.32 ± 0.04 cm, and PL: 0.35 ± 0.03 cm. Microbiota analysis identified predominantly gram-positive bacteria, with Staphylococcus sp. being the most common (47.5%). Anatomical evaluation of skulls revealed a large lacrimal process extending to the zygomatic process, and the margins of the processes intersect but do not fuse. Young parakeets exhibit a brownish iris that gradually turns blue by 60 days of age.

These findings may contribute to the diagnosis of ophthalmic conditions in this species and provide insight into normal anatomical features.