Ocular Ultrasonography in Normal and Diseased Donkeys

Abstract

Ocular opacities can hinder appropriate examination of posterior structures using ophthalmoscopy and/or slit lamp biomicroscopy in circumstances such as corneal disease, uveitis, cataracts, or trauma. Ultrasonography, in contrast to these examination modalities, has the benefit of providing a complete image of the globe regardless of opacities in the anterior segment and lens. The technique is safe, rapid, non-invasive, and painless. This study was performed using10-12-MHz linear transducers (Hitachi Aloka F31, Japan & SonoVet R3, Samsung Medison, South Korea) with color Doppler for transpalpebral ocular ultrasonography. This study included 85 donkeys, 40 with clinically normal eyes grouped according to gender and maturity to (10 mature males, 10 immature males, 10 mature females, and 10 immature females) for identification of normal ocular anatomy, biometry, and blood flow indices, and 45 donkeys for diagnoses of various ocular diseases. In this study, the cornea appeared as a hyper echoic curved line, the anterior chamber as an anechoic area filled with aqueous humor in front of the iris, and the ciliary body which appeared as hyper echoic thin linear structure in front of the anterior lens capsule (ALC) and an irregular thick semi triangular echogenic structure present on both sides of the lens. The lens appeared as an anechoic structure that has been lined anteriorly and posteriorly with the hyper echoic anterior lens capsule (ALC) and posterior lens capsule (PLC) in front of the totally anechoic vitreous body that filled the cavity of the posterior segment of the eye in front of the hyper echoic posterior ocular wall that represented the retina, choroid, and sclera. The optical disc was found near the posterior ocular wall, which was significantly more echogenic than the wall itself. The optical nerve was observed as a funnel-shaped hypoechoic structure that ran caudal to the echogenic optical disc. The retrobulbar echogenic fat pads around the optic nerve were recognized, however the retrobulbar muscles could not be seen clearly.