Preliminary findings in 30 dogs treated with micropulse transscleral cyclophotocoagulation for refractory glaucoma

Abstract

Objective The purpose of this study was to report the preliminary results of a novel micropulse transscleral diode laser cyclophotocoagulation (MP‐TSCP) as primary therapy for glaucomatous dogs. Animal Studied Client owned dogs undergoing MP‐TSCP therapy at a veterinary referral center. Procedure Retrospective study of dogs with glaucoma that were treated with MP‐TSCP with a minimum of 1 month (range: 1‐18 months) of follow‐up. Reported outcomes were intraocular pressure (IOP), treatment parameters, reduction in medications, complications, and incidence of repeat therapy. Results Thirty dogs (35 eyes) were evaluated. The mean age was 9.0 years. Mean preoperative IOP was 34.5 mm Hg. Mean postoperative IOP at 1 month (35/35 eyes) was 22 mm Hg, 2 months (26/35 eyes) was 20.5 mm Hg, 4 months (20/35 eyes) was 19 mm Hg, 6 months (10/35 eyes) was 19 mm Hg, 12 months (8/35 eyes) was 21 mm Hg. First treatment success rate was 19/35 eyes (54.3%). Repeat laser was performed in 11 eyes with 4/11 eyes responding favorably for a total IOP control of 23/35 eyes (65.7%). Mean energy levels employed were 137.5 seconds and 2351 mW at 31.3% duty cycle. Reduction in medications was from a mean of 3.6 medications preoperatively to 3.1 medications postoperatively. Complications included corneal ulcers 5/35 eyes (14.3%), uncontrolled IOP in 12/35 eyes (34.3%) and repeat treatment in 11/35 eyes (31.4%). Conclusions MP‐TSCP was successful in controlling IOP in most patients as well as to reduce postoperative medications with minimal resultant intraocular inflammation and complications. The micropulse procedure also can be repeated. Future investigations to study effective treatment parameters are warranted in a larger series of patients over a longer period of evaluation.

MicroPulse™transscleral cyclophotocoagulation in the treatment of canine glaucoma: Preliminary results (12 dogs)

“…The majority of dogs treated with MP‐TSCPC (11/12, 92%) initially responded favorably to the procedure and maintained IOP <25 mm Hg for 3 months (10/12, 83%), similar to findings by Sapienza and colleagues, who reported IOP control in 81.2% of treated canine eyes at 2 months post‐operatively . Long‐term follow‐up of our dogs (mean 315 days) showed IOP control and retention of vision in 42% and 50% of cases, respectively.…”

“…Lastly, the lack of significant reduction in post‐operative anti‐glaucoma medications represents another disadvantage of MP‐TSCPC, and the variability in the number of anti‐glaucoma medications used post‐operatively could represent another confounding factor in the procedure's efficacy reported herein. The frequency of anti‐glaucoma therapy may decrease in the short term, but eventually returned to near baseline. However, this finding is contrary to studies in human patients and warrants verification by future canine studies that employ standardized MP‐TSCPC protocols …”

The future of canine glaucoma therapy

“…A novel technique currently being evaluated for TSCP is the use of micropulse laser (Figure ; MicroPulse ® Cyclo G6; Iridex) . The proposed main advantage of micropulse TSCP is the short wave of energy followed by an off cycle that allows the adjacent nonpigmented tissue to cool off, thereby minimizing any collateral thermal damage to adjacent tissues . The exact mechanism of action of micropulse TSCP still needs to be determined, but may consist not only of ciliary ablation but also improved conventional and uveoscleral aqueous humor outflow .…”

“…78,79 The exact mechanism of action of micropulse TSCP still needs to be determined, but may consist not only of ciliary ablation but also improved conventional and uveoscleral aqueous humor outflow. 78,79 Preliminary results about the effectiveness of the micropulse laser in dogs are mixed, with a need to refine protocols and patient selection to improve long-term IOP-lowering treatment effect and reduce the rate of complications, such as corneal ulceration. 79,80 Diode ECP is an attractive alternative to TSCP in the treatment of canine glaucoma.…”

“…78,79 Preliminary results about the effectiveness of the micropulse laser in dogs are mixed, with a need to refine protocols and patient selection to improve long-term IOP-lowering treatment effect and reduce the rate of complications, such as corneal ulceration. 79,80 Diode ECP is an attractive alternative to TSCP in the treatment of canine glaucoma. It is combined with lens removal by phacoemulsification, or it also can be used for prophylactic treatment combined with cataract removal in dogs at increased risk of glaucoma development.…”