B-Scan Biometry and Color Doppler Ultrasound Imaging of the Eye in Clinically Normal Donkeys (Equus asinus): Effect of Laterality, Maturity and Gender.

Despite the extensive research on ocular ultrasonography, there is paucity of information regarding ocular biometry and color Doppler imaging of the donkey's eye. This study establishes B-scan ocular biometry and color Doppler ultrasonographic reference values in normal donkeys and describes effect of laterality, maturity and gender on ocular biometry and vasculature. Forty (80 eyes) clinically normal immature and mature donkeys of both sexes were included. Transpalpebral ocular ultrasonography was made using a 12-MHz linear transducer. Biometric ocular measurements were made including the anterior chamber depth, central lens thickness, vitreous chamber depth, axial globe length, longitudinal globe length, lens pole diameter and posterior wall thickness. Color Doppler velocimetric measurements including peak systolic velocity and end-diastolic velocity were made. Blood flow indices represented by resistive and pulsatility indices were calculated. Results revealed that laterality and gender did not represent variability factors in ocular biometry (P >.05), while the animal's maturity had an influence on axial globe length (P <.001), longitudinal globe length (P = 0.000) and lens pole diameter (P = .000). Laterality had no effect on velocimetric parameters and indices (P >.05) while gender had significant effect on resistive index (P = .024), pulstality index (P = .000) and volume flow per area (P = .008). The state of maturity had significant effects on peak systolic velocity (P = .027) and blood volume flow per distance (P = .012), and area (P = .048). Ocular biometry and color Doppler ultrasonography provided a clinically useful tool to evaluate the donkey's eye that will be helpful in diagnosing donkeys with ocular diseases.