Decreased macular thickness in nonproliferative macular telangiectasia type 2 with oral carbonic anhydrase inhibitors

PURPOSE: To evaluate whether carbonic anhydrase inhibitors reduce the macular thickness and/or cystic spaces in patients with macular telangiectasia (MacTel) Type 2. METHODS: Retrospective review of patients with nonproliferative cystoid changes associated with MacTel seen at the University of Iowa between 2009 and 2012. Carbonic anhydrase inhibitors were used in 8 patients with MacTel Type 2. Five patients with MacTel Type 2 were observed during this period. Initial and final visual acuities were documented. The presence of cystic spaces and the retinal thickness were measured with spectral-domain optical coherence tomography. RESULTS: Patients treated with oral carbonic anhydrase inhibitors showed significant reduction in both the cystoid cavities and central macular thickness when compared with the patients who were observed (-12.2 μm; P = 0.020). The reduction in retinal thickness was more pronounced in patients receiving acetazolamide (-20.13 μm; P = 0.007) compared with methazolamide (-6.25 μm; P = 0.177). There was no significant change in visual acuity in patients receiving carbonic anhydrase inhibitors. Five patients with MacTel Type 2 did not receive treatment and demonstrated no change in visual acuity, cystoid cavities, or central macular thickness. CONCLUSION: Oral carbonic anhydrase inhibitors, particularly acetazolamide, may decrease macular cystic cavities and reduce central macular thickness but does not appear to improve visual acuity. These findings have yet to be confirmed with a prospective treatment trial.