Photobiomodulation in dry age-related macular degeneration.

Abstract

We read with great interest the article by Merry et al. (2016) on photobiomodulation (PBM) in dry age-related macular degeneration (AMD). The tremendous results of PBM in the improvement of best-corrected visual acuity and contrast sensitivity notwithstanding, there were certain misgivings in their study which they succinctly highlighted as well. A previous similar study (TORPA) by the same authors found no difference in the preferential retinal locus (PRL) in 18 subjects treated with PBM on microperimetry (Merry et al. 2012, ARVO abstract). Preferential retinal locus (PRL) is a surrogate marker for improved and steady fixation. Microperimetry was not employed in this follow-up study. It would be interesting to see the subjective change in PRL and improvement in microperimetry in the subjects using PBM. Fundus autofluorescence (FAF), central retinal thickness (CRT) and retinal volume (RV) used as anatomical adjuncts for the change in dry AMD with PBM showed no significant improvement and in fact showed mild worsening of FAF at visit 2 (3 months). While drusen volume showed a significant change for the better, it seems odd that the FAF, which is a surrogate for retinal pigment epithelium function, showed worsening in area. The authors could try to explain this paradox. Despite these limitations, we are glad to see a novel therapeutic modality has a significant impact in dry AMD which offers more hope to AMD patients. We congratulate the authors for the outstanding results and hope to see a dose ranging of PBM would help identify the beneficial effect of specific wavelengths in AMD.