The location of sites and effect of semiconductor diode trans-scleral cyclophotocoagulation on the buphthalmic equine globe.
OBJECTIVE
To determine appropriate location and energy settings for trans-scleral cyclophotocoagulation (TSCPC) for buphthalmic equine globes.


METHODS
Eleven horses with a buphthalmic eye blinded by glaucoma presented for enucleation.


METHODS
Globe and corneal dimensions were measured via ultrasonography and calipers, and TSCPC was performed under general anesthesia immediately prior to enucleation. Part 1: In nine globes, sixty sites were lasered 4 mm posterior to the limbus in the dorsotemporal and ventrotemporal quadrants at settings of 1500 milliwatts and 1500 ms. Globes were processed and sectioned sagitally over the temporal aspect in two blocks, each with five histologic sections examined by light microscopy. A digital imaging system was used to determine the location and length of the pars plicata on one slide from each block. Part 2: Based on results in Part 1, two globes were measured and lasered using the same time and energy settings at the following distances posterior to the limbus: 8 mm dorsally, 6 mm dorsotemporally, 5 mm ventrotemporally, and 5 mm ventrally.


RESULTS
Globe and corneal dimensions exceeded normal values in all globes. Part 1: In all nine globes, photocoagulation affected the anterior ciliary processes and iris base and in 8/9 coagulation of the pectinate ligaments was noted. Part 2: In both globes, coagulation was confined to the pars plicata.


CONCLUSIONS
The previously recommended TSCPC sites are located too far anteriorly for a buphthalmic globe. Buphthalmic equine globes should have TSCPC performed at the following distances posterior to the limbus: 6-8 mm dorsally, 5-6 mm dorsotemporally, 4-5 mm ventrotemporally, and 4-5 mm ventrally.
Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, OH, 43210, USA.
Anne J
AJ
Gemensky-Metzler
David A
DA
Wilkie
Steven E
SE
Weisbrode
Sonia E
SE
Kuhn
D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000473:pathology / Q000601:surgery*; D006736:Horses; D006871:Hydrophthalmos / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D017075:Laser Coagulation / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D054023:Lasers, Semiconductor; D008297:Male
Buphthalmic; equine; glaucoma; histology; semiconductor diode laser; trans-scleral cyclophotocoagulation