670 nm Photobiomodulation as a Therapy for Diabetic Macular Edema: A Pilot Study

Abstract

Purpose : Diabetic macular edema (DME) is a common complication of diabetes mellitus. Photobiomodulation (PBM) by far-red to near infrared (NIR) light has been demonstrated to improve retinal function in experimental and clinical retinal disease. Although anti-vascular endothelial growth factor (anti-VEGF) agents have revolutionized treatment for DME, some eyes are treatment resistant. Here we tested the hypothesis that NIR PBM will attenuate the severity of diabetic macular edema and improve visual acuity in patients with DME.

Methods : A randomized prospective pilot study was conducted in accordance with the Declaration of Helsinki and the study protocol was approved by the IRB at the Medical College of Wisconsin. Ten adult patients (66 ± 3 years, 7 males, 3 females) with treatment resistant DME were randomized into standard treatment (STD-TRT; anti-VEGF therapy alone) and PBM treatment (PBM-TRT; anti-VEGF plus PBM) groups. Light treatment was administered at a dose of 4.5 J/cm² three consecutive days per week for 8 weeks using a 670 nm LED Array (WARP-10, Quantum Devices, Inc., Barneveld, WI) positioned 2.5 cm from the closed treatment eye. Functional and anatomic assessments were made at baseline, 8 weeks and 24 weeks.

Results : At 24 weeks, visual acuity (VA) decreased from baseline in STD-TRT subjects (-3 ± 4 letters; n=4). In contrast VA was improved from baseline at 24 weeks in PBM-TRT subjects (6 ± 5 letters; n=6). Central retinal thickness by OCT was increased from baseline at 24 weeks in STD-TRT subjects (120 ± 97 µm; n=4) and was decreased from baseline at 24 weeks in PBM-TRT subjects (-24 ± 5 µm; n=6). These findings are suggestive of a reduction in macular edema and an improvement in vision following NIR-PBM. No adverse effects attributable to NIR-PBM were noted by the patients or study investigators during the study period.

Conclusions : Although the sample size is small, the findings show a reduction in DME and an improvement in VA following NIR-PBM. Results support the application of NIR-PBM for the treatment of DME in eyes refractory to anti-VEGF treatments. This is consistent with previous studies showing NIR-PBM improves retinal function in experimental and clinical retinal disease. The use of NIR-PBM is non-invasive, safe and may be an effective adjunct therapy for DME.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.