Photobiomodulation reduces drusen volume and improves visual acuity and contrast sensitivity in dry age-related macular degeneration

Abstract

Purpose: To evaluate the efficacy of photobiomodulation (PBM) treatment for patients with dry age-related macular degeneration (AMD).

Methods: Assessments on 42 eyes with dry AMD (age related eye disease study (AREDS) 2-4) were conducted. Multiwavelength light emitting diode (LED) light comprising of yellow (590 nm), red (670 nm) and near-infrared (790 nm) bandwidths was applied to subjects' eyes for a treatment course of 3 weeks. Outcome measures were changes in best-corrected visual acuity (BCVA), contrast sensitivity (CS), drusen volume and central drusen thickness.

Results: Significant improvement in mean BCVA of 5.90 letters (p < 0.001) was seen on completion of the 3-week treatment and 5.14 letters (p < 0.001) after 3 months. Contrast sensitivity improved significantly (log unit improvement of 0.11 (p = 0.02) at 3 weeks and 3 months (log unit improvement of 0.16 (p = 0.02) at three cycles per degree. Drusen volume decreased by 0.024 mm³ (p < 0.001) and central drusen thickness was significantly reduced by a mean of 3.78 μm (p < 0.001), while overall central retinal thickness and retinal volume remained stable.

Conclusion: This is the first study demonstrating improvements in functional and anatomical outcomes in dry AMD subjects with PBM therapy. These findings corroborate an earlier pilot study that looked at functional outcome measures. The addition of anatomical evidence contributes to the basis for further development of a non-invasive PBM treatment for dry AMD.

Keywords: age-related macular degeneration; contrast; drusen; photobiomodulation; sensitivity; visual acuity.

Figure 1

Representative images from two different patients showing characteristic pathologic changes. Semi‐automated segmentation in optical coherence tomography (OCT) and geographic atrophy (GA) assessment in fundus autofluorescence (FAF) were performed. The left image (A) displays a representative drusen volume map of an AREDS 3 patient. Colour bars indicate ascending thickness values starting with 0 μm (black). The image in the middle (B) demonstrates the drusen alignment in one representative OCT section scan of the same patient. The right image (C) illustrates the assessment of the GA area using FAF at 488 nm wavelength in a patient with central involving GA of an AREDS 4 patient. The GA is measured by manually marking the area of homogenous hypo‐autofluorescence using the inbuilt Heidelberg software (yellow line).

Figure 2

(A) Photobiomodulation (PBM) leads to significant improvement in early treatment diabetic retinopathy study (ETDRS) letter score (absolute plot – jitter) in individual subjects. The bold dotted line indicates the overall mean. (B) Contrast sensitivity (CS; 3.0 CPD) in logCS change from baseline (BL) following PBM treatment (absolute plot – jitter) in individual subjects. The bold dotted line indicates the overall mean. (C) This panel indicates the percentage of eyes presenting with one, two and three line ETDRS letter gain at visit 1 ( = immediate post‐treatment, 3 weeks after BL). (D) Drusen volume measurements in mm³ change from BL following PBM treatment (absolute plot – jitter) in individual subjects. The bold dotted line indicates the overall mean.

Figure 3

Visual acuity change in magnitude categorized by baseline (BL) VA scores. Eyes with a BL VA letter score of between 70 and 89 (Snellen equivalent of 20/80–20/32) appeared to respond to photobiomodulation treatment with a high percentage gaining greater than five letters. Eyes with lower (60–69 letters) or higher (≥90 letters) BL VA letter score were less likely to gain more than five letters.

Figure 4

Representative example of an eye categorized as AREDS 3 with mainly convex, homogenous and low reflective drusen larger than 125 μm. Baseline (Top) shows a drusen volume of 0.39 mm³ with a mean central 1‐mm drusen with thickness of 29 μm. Black numbers indicate the mean drusen thickness of each early treatment diabetic retinopathy study subgrid and red numbers indicate the corresponding drusen volume (mm³). Bottom: Follow‐up examination at visit 1. Overall drusen volume as well as mean central drusen thickness has significantly decreased without new formation of geographic atrophy or disruption of the photoreceptor layers.

Figure 5

An individual cut segmented subtraction scan showing significant drusen regression at 3 months following the treatment course.