Ultrasonographic features of PMEL17 (Silver) mutant gene–associated multiple congenital ocular anomalies (MCOA) in Comtois and Rocky Mountain horses
Article first published online: 1 JAN 2013
© 2013 American College of Veterinary Ophthalmologists
Volume 16, Issue 6, pages 429–435, November 2013
How to Cite
Ségard, E. M., Depecker, M. C., Lang, J., Gemperli, A. and Cadoré, J.-L. (2013), Ultrasonographic features of PMEL17 (Silver) mutant gene–associated multiple congenital ocular anomalies (MCOA) in Comtois and Rocky Mountain horses. Veterinary Ophthalmology, 16: 429–435. doi: 10.1111/vop.12021
- Issue published online: 28 OCT 2013
- Article first published online: 1 JAN 2013
- multiple congenital ocular anomalies;
- silver dapple gene;
(1) To describe the ultrasonographic appearance of multiple congenital ocular anomalies (MCOA) in the eyes of horses with the PMEL17 (Silver) mutant gene. (2) To compare the accuracy of B-mode ocular ultrasound to conventional direct ophthalmoscopy.
Sixty-seven Comtois and 18 Rocky Mountain horses were included in the study.
Horses were classified as being carriers or noncarriers of the PMEL17 mutant allele based on coat color or genetic testing. Direct ophthalmoscopy followed by standardized ultrasonographic examination was performed in all horses.
Seventy-five of 85 horses (88.24%) carried at least one copy of the Silver mutant allele. Cornea globosa, severe iridal hypoplasia, uveal cysts, cataracts, and retinal detachment could be appreciated with ultrasound. Carrier horses had statistically significantly increased anterior chamber depth and decreased thickness of anterior uvea compared with noncarriers (P < 0.05). Uveal cysts had a wide range of location and ultrasonographic appearances. In 51/73 (69.86%) carrier horses, ultrasound detected ciliary cysts that were missed with direct ophthalmoscopy.
In this study, ultrasonography was useful to identify uveal cysts in PMEL17 mutant carriers and to assess anterior chamber depth.