A preliminary observation on rod cell photobiomodulation in treating diabetic macular edema

Purpose: To evaluate the safety and effectiveness of photobiomodulation (PBM) in the treatment of diabetic macular edema (DME). Methods: It was a single-center, self-controlled prospective study. The clinical records of 12 diabetic retinopathy patients (5 males and 7 females, 20 eyes in total) who were treated with PBM for DME at the Second Affiliated Hospital, Zhejiang University School of Medicine, were analyzed. The mean age was 56 (26-68) years. All the participants received PBM treatment during darkness at night in no less than 5 days per week and no less than 8 h per day. In the baseline check and follow-up checks (1, 2, 6, 10, and 12 months after the start of treatment), the best-corrected visual acuity, the thickness of the retina in the macula, and the changes of the fundus lesions were observed. Wilcoxon signed rank test was used to compare the results before and after treatment. P < 0.05 was considered statistically significant. Results: No fundus complication was observed during follow-up checks. In baseline and 12-month follow-up checks, the best-corrected visual acuity was 71.75 +/- 12.47 and 79.50 +/- 10.85, maximal retinal thickness in macular area was 390.95 +/- 77.12 mu m and 354.13 +/- 55.03 mu m, average retinal thickness in macular area was 334.25 +/- 36.45 mu m and 314.31 +/- 33.28 mu m, foveal thickness was 287.00 +/- 46.79 mu m and 265.63 +/- 67.14 mu m. The best-corrected visual acuity, average retinal thickness in macular area in consecutive follow-up results except that in the 1st month showed significant difference compared with baseline results. There were significant difference between every follow-up result and baseline result of maximal retinal thickness in macular area (P < 0.05). All follow-up results of foveal thickness were not significantly different (P > 0.05) from the baseline result, except that in the 6th month (P = 0.049). Obvious improvement could be observed in retinal fundus fluorescein angiography images. Conclusions: PBM is a safe and effective treatment of DME, which deserves further investigation.