MicroPulse™ transscleral cyclophotocoagulation in the equine patient: A case series of four horses

To describe the clinical application and outcome of MicroPulse™ transscleral cyclophotocoagulation (MP-TSCPC) treatment in horses with glaucoma.

Four client-owned horses with primary (n = 2) or secondary (n = 2) glaucoma.

Horses were treated with MP-TSCPC under standing sedation with a minimum of 30 days of follow-up (range 30-1241 days). Affected eyes were treated with a 31.3% duty cycle and 3000 mW laser power for a total of 180 s. Data collected included signalment, pre- and post-procedure intraocular pressures (IOPs), laser settings, medications, complications, and repeat therapy.

Four horses (5 eyes) received at least one treatment with MP-TSCPC. Mean preoperative IOP was 44 mmHg (range 33-49 mmHg). The immediate mean postoperative IOP was 34 mmHg (4 eyes; range 19-55 mmHg). At 1 week, IOP was 38 mmHg (5 eyes; range 21-80 mmHg), at 2 weeks was 40 mmHg (3 eyes, range 17-80 mmHg), at 1 month was 35 mmHg (5 eyes; range 20-50 mmHg), at 3 months was 18 mmHg (2 eyes; range 14-21 mmHg), at 6 months was 35 mmHg (2 eyes; range 30-39 mmHg), and at >300 days was 24 mmHg (3 eyes; range 18-29 mmHg). Complications included corneal ulceration (n = 1 eye), uncontrolled IOP (n = 3 eyes), and need for repeat treatment (n = 2 eyes).

MP-TSCPC used with the above-described settings was unsuccessful in treating the majority of cases. Future studies should be targeted at primary glaucoma cases and with use of alternative laser settings.