Diode laser endoscopic cyclophotocoagulation in the normal equine eye.
OBJECTIVE
To determine the clinical and histologic effects of diode endoscopic cyclophotocoagulation (ECP) in the phakic equine eye.


METHODS
Phase I: 10 equine cadaver eyes. Phase II: four normal adult horses.


METHODS
Phase I: ECP probe angle of reach (AR) was determined. Multiple ECP energy levels: 0.75, 0.90, 1.05, 1.20, 1.35, 1.50 J, and the resulting visible and histologic ciliary process changes were evaluated. Phase II: Ocular quadrants were treated with ECP at 0.90, 1.14, 1.38 J, and a control. The contralateral eye underwent a sham operation. Tissue changes (clinical and histologic) were evaluated.


RESULTS
Phase I: Mean combined AR was 162 ± 29 degrees. Mean visible tissue scores: 2.60 ± 0.58 (0.75 J) to 5.04 ± 0.30 (1.50 J) from possible total of 6. Tissue 'popping' was observed at 1.50 J. Histologic ciliary tissue damage was present at all settings. Phase II: Mean visible tissue scores: 2.90 ± 0.48 (0.90 J), 3.61 ± 0.57 (1.14 J), and 4.52 ± 0.56 (1.38 J). Tissue 'popping' was observed at 1.38 J. Histologic ciliary tissue damage was present at all settings. Clinical effects included acute inflammation, intraocular pressure reduction, cataract formation, corneal edema, corneal ulceration, and postoperative ocular hypertension.


CONCLUSIONS
Diode ECP between 0.90 and 1.14 J is a potential treatment option for glaucoma in horses based on visible tissue effects and target ciliary epithelium damage. Iatrogenic cataract development may limit the use of an anterior chamber approach in phakic horses. Supported in part by an ACVO VAF grant.
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
Jay T
JT
Harrington
Richard J
RJ
McMullen
John M
JM
Cullen
Nigel B
NB
Campbell
Brian C
BC
Gilger
D000818:Animals; D002102:Cadaver; D019723:Endoscopes / Q000662:veterinary*; D005123:Eye; D006736:Horses; D054023:Lasers, Semiconductor; D008028:Light Coagulation / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D013508:Ophthalmologic Surgical Procedures / Q000379:methods / Q000662:veterinary*