Abstract
Limited evidence suggests that the application of 670 nm of red light alters the course of aged decline. A previous report on 18 patients showed regression of drusen and improvement in visual functions in patients with intermediate age-related macular degeneration (AMD) by 12 months. We evaluated the functional and structural effects of applying 670 nm light to 31 patients with intermediate AMD and 11 people aged 55 years or above with normal retina. The study eyes were treated daily in the morning with a 670 nm hand-held light source housed in a torch-like tube that emitted energy equivalent to 40 mW/cm2 or 4.8J/ cm2 for 2 min at the viewing aperture. Visual function in terms of best-corrected visual acuity, low luminance visual acuity, scotopic thresholds and rod-intercept time were compared between baseline and 1, 3, 6 and 12 months. Structural changes on optical coherence tomography OCT and colour photographs were also assessed. Five withdrew consent voluntarily due to the intensity of the study visit assessments and two developed neovascular AMD and were excluded from further treatment and the analysis. In normal ageing, there was an improvement in scotopic thresholds in the group with no AMD by 1.77dB (p = 0.03) and no other parameters showed any clinically significant change. In eyes with intermediate AMD, there was no significant improvement in any functional or structural changes at any time point up to 12 months although the compliance was good. This pilot study shows that photobiomodulation with 670 nm has no effect in patients who have already progressed to intermediate AMD.
Highlights
In healthy ageing and age-related macular degeneration (AMD), there is a progressive loss of rod photoreceptors compared to a minimal decline of the less vulnerable cone photoreceptors [1]
When healthy eyes convert to AMD, the early visible changes are characterized by accumulation of sub-retinal pigment epithelium (RPE) deposits called drusen and in some cases subretinal drusenoid deposits (SDD), otherwise termed reticular pseudodrusen (RPD) [3,4]
SDD were visible in eight eyes with intermediate AMD (iAMD)
Summary
In healthy ageing and age-related macular degeneration (AMD), there is a progressive loss of rod photoreceptors compared to a minimal decline of the less vulnerable cone photoreceptors [1]. When healthy eyes convert to AMD, the early visible changes are characterized by accumulation of sub-RPE deposits called drusen and in some cases subretinal drusenoid deposits (SDD), otherwise termed reticular pseudodrusen (RPD) [3,4]. None of these signs affect visual acuity but rod-recovery time from a bright flash is delayed and this test can accurately discriminate between healthy ageing of the retina and eyes with AMD [5,6]. As visual acuity is not an appropriate outcome measure for early or iAMD, we aimed to establish the possible therapeutic effect of 670 nm light exposure on multiple visual functions and anatomical structures in healthy ageing and AMD with and without SDD to assess whether any of the tests could be reliably used in a future definitive randomized controlled trial on photobiomodulation in AMD
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