Ocular Parameters in Healthy Sakız and Çine Çaparı Sheep Breeds: Tear Production, Intraocular Pressure, Ultrasonographic Measurements, and Retinal Variations.

OBJECTIVE

This study aimed to determine and compare normal variations in tear production, intraocular pressure, B-mode ultrasonographic findings, and the fundus in healthy Sakız and Çine Çaparı sheep.

METHODS

Sixty healthy female sheep (30 Sakız and 30 Çine Çaparı), approximately 2 years old, were included. The Schirmer-I tear test (STT-I), rebound tonometry for IOP, B-mode ocular ultrasonography, and fundus photography following mydriasis were performed.

RESULTS

STT-I values were significantly higher in Sakız sheep compared to Çine Çaparı (18.87 ± 0.51 mm/min vs. 15.82 ± 0.61 mm/min; p < 0.001). IOP was also slightly higher in Sakız sheep (16.40 ± 0.42 mmHg vs. 15.75 ± 0.60 mmHg; p < 0.05). Significant differences were observed in some ultrasonographic parameters, such as lens length (M4: 12.8 ± 0.1 mm in Sakız vs. 13.6 ± 0.1 mm in Çine Çaparı; p < 0.01) and vitreous chamber depth (M5: 12.6 ± 0.1 mm vs. 11.8 ± 0.1 mm; p < 0.01) in mean value of both eyes. Fundus evaluation revealed breed-specific variations in tapetal color (more consistent blue-green in Sakız, variable green tones in Çine Çaparı), nontapetal pigmentation (uniformly black in Sakız vs. mixed brown and black in Çine Çaparı), and optic disk shape (predominantly oval in both). Bergmeister's papilla was more prevalent in Sakız sheep (p < 0.05), while arterial and venous distributions in the nontapetal region differed slightly between breeds without statistical significance.

DISCUSSION: It was determined that tear production; IOP; B-mode ultrasonography findings; and normal variations of the fundus in Sakız and Çine Çaparı sheep exhibited similar distributions, albeit with minor differences.