Determination of ocular biometrics and ophthalmic parameters in brachycephalic dog breeds

Objective: In this study, the aim was to determine ocular biometry and ophthalmic parameters in ophthalmologically healthy brachycephalic dogs and to investigate whether there is any correlation between the obtained data. Materials and Methods: The study material consisted of 30 brachycephalic dogs (8 females and 22 males) brought to the Aydın Adnan Menderes University Faculty of Veterinary Medicine, Department of Surgery Clinic for treatment, but ophthalmologically healthy. In this study, reflex examinations, Schirmer tear test, intraocular pressure, central corneal thickness, and ocular ultrasound examination were performed on the brachycephalic dogs. After the ultrasound examination, the axial length of the eye, anterior chamber depth, lens thickness, lens length, and vitreous depth of the dogs were measured. The obtained measurements were statistically evaluated. Results: The cumulative averages were taken from the data obtained from the dogs without differentiating by breed, age, and gender. According to this average, the Schirmer tear test I values were found to be 19.80 ± 0.77 mm/min, intraocular pressure values were 19.46 ± 0.74 mmHg, and central corneal thickness was 586.66 ± 5.37 µm. In the ultrasonographic examinations, the cornea was identified as a hyperechoic line, the anterior and posterior lens capsules as hyperechoic, and the cortex as an anechoic structure. The vitreous body was observed as an anechoic area behind the lens. The measurements taken were as follows: axial length 17.50 ± 0.15 mm, anterior chamber depth 2.01 ± 0.05 mm, lens thickness 6.59 ± 0.10 mm, lens length 15.01 ± 0.42 mm, and vitreous depth 8.52 ± 0.15 mm. Conclusion: The data obtained in this study were within the normal reference range. Moderate correlations were identified between intraocular pressure and both axial length and lens thickness. Additionally, a positive correlation was found between axial length and vitreous body depth. Keywords: Brachycephalic dogs, Ocular biometry, Ophthalmic parameters.