Alternate day vs daily topical brinzolamide in the treatment of cystic maculopathy in inherited rod cone retinal degenerations

Abstract

Purpose Cystic maculopathy (CM) occurs in 10-50% of all inherited rod cone retinal degenerations (RCD), further compromising the small remaining central field of vision. Oral and topical carbonic anhydrase inhibitors, have been used with some effect, but rebound can occur. Discontinuation or Alternate day treatment with topical Brinzolamide may alleviate this effect. We assessed treatment response in alternate day vs continuous day dosing. Methods Retrospective chart review of patients with RCD from the New Zealand database of Inherited Retinal Disease.Outcomes were objective vision (VA)(≥7 letters significant), subjective VA, OCT analysis including reduction of cyst size, central macular thickness (CMT) ( ≥11% significant), and macular volume (MV). Treatment response was correlated with inheritance pattern and genotype. Results Of 256 patients with RCD identified, 62 (24%) had CM, present in 40% with autosomal dominant (AD), 24% with autosomal recessive (AR), and absent in X-Linked RCD. Complete data was available for 28 patients (54 eyes) on alternate day regimen (Group 1), and 18 patients (32 eyes) on continuous treatment (group 2). Median treatment was 32 months (6-48). Group 1: 55% showed any response : 71 % had subjective VA improvement, objective VA improvement 50%, mean reductions in CFT 105µm (95%CI 82-128), and MV 1.1mm3 (0.5-1.9) Group 2: 37% showed any response – 75% had subjective VA improvement, 44% objective VA improvement , mean reductions in CMT 120µm (52-178), and MV of 1.5mm3 (0.8-1.8). Alternate day treatment compared with continuous was associated with a better response (p=0.04), with odds ratio(OR) for VA improvement 12.7 (95% CI 1.1-146.7). ARRCD had a significant association with improvement (p=0.01), OR 31.25 (2.5-468.9) compared with ADRCD. Of patients with proven PRPF31 RCD, 80% had CM. Conclusions CM associated with inherited RCD affects 25% of patients, and is more frequent in AD disease, but a larger treatment response to topical brinzolamide observed in AR disease. Alternate day dosing is more effective than continuous in CMT reduction, and objective VA improvement. Subjective improvement was greater suggesting other parameters such as contrast sensitivity may be improved. Alternate day dosing with brinzolamide works more effectively than continuous dosing with less rebound, and may be due to RPE pump recovery. Layman Leaking in the central part of the retina can occur in one quarter of people with inherited retinal disease, making their precious central vision worse. Using a drop (brinzolamide ) every second day, rather than daily, improved the amount of leaking, and may give the sick cells at the back of the eye a chance to rest and recover on the day off treatment.