Subthreshold (invisible) modified grid diode laser photocoagulation in diffuse diabetic macular edema (DDME)

BACKGROUND AND OBJECTIVE: To determine the effectiveness of subthreshold (i nvisible) diode laser (810 nm) modified grid photocoagulation For the treat ment of diffuse diabetic macular edema (DDME), METHODS: Fifty eyes of 29 patients were treated with subthreshold (invisibl e) diode laser modified grid photocoagulation for DDME in a prospective pil ot clinical trial. Follow-up was conducted for a minimum of 6 months (avera ge: 14.11 +/- 6.15 months). Retreatment was performed for residual edema in volving the foveal avascular zone. Ten patients were tested with Goldman vi sual field pre- and post-treatment. Visual improvement, visual loss, visual field, reduction/elimination of macular edema, and the number of treatment s per eye were studied. RESULTS: Reduction/elimination of DDME was observed in 39% of the eyes afte r 1 to 3 treatments (2.22 +/- 0.84 treatments) in 6 to 12 months; and in 74 % of eyes after 1 to 5 treatments (2.90 +/- 1.02 treatments) 15-24 months f ollow-up. The presence of cystoid macular edema, initial poor visual acuity , or a history of systemic hypertension did not affect the outcome. Patient s without a history of systemic vascular diseases had a better chance of vi sual stabilization or improvement. Eighty-eight percent of the patients had at least stable vision at the last follow-up. Two out of 10 visual field t ests showed a decrease in paracentral scotomas; no post-treatment subjectiv e complaints of increased paracentral scotomas were encountered. CONCLUSION: Subthreshold (invisible) diode laser modified grid photocoagula tion is effective in reducing/eliminating DDME, although resolution of edem a may be slightly prolonged. However, this method may be advantageous in th at it appears to reduce the objective and subjective effect on the paracent ral visual field. Subthreshold (invisible) diode laser modified nd photocoa gulation substantially reduces the post-treatment atrophic scarring.