Red light therapy for the eyes has a small, measured benefit in one group and a documented risk in another. In a small trial at University College London (UCL), researchers found that a few minutes a day of deep red LED light improved color vision in healthy adults over about 40. In children, laser devices that shine red light into the eye to slow myopia (nearsightedness) can exceed retinal safety limits, and eye doctors have reported retinal damage.
Sellers of home red light lamps also claim the light eases eye strain. That claim is unknown based on available sources: none of the studies below tested eye strain.
What deep red light did for aging eyes
The best known human data on red light therapy for eyes come from Professor Glen Jeffery’s team at UCL. The team recruited 24 people aged 28 to 72 with no eye disease and asked them to look into a small deep red LED torch for three minutes a day for two weeks. According to the university, the torch gave off light with a wavelength of 670 nanometers (nm).
According to the university, color contrast sensitivity (the ability to pick out faint colors) improved by up to 20% in some people aged around 40 and over, with the largest gains on the blue side of the color range. The same release says rod sensitivity, which lets people see in dim light, also improved in that age group. People younger than about 40 showed no change, the university reported.
The idea behind the treatment is cell energy. Mitochondria (the cell’s power plants) are packed most densely in the retina’s light-sensing cells, and the university reports that the retina loses about 70% of its energy supply (ATP) over a lifetime. In the same release, Jeffery says light between 650 and 1,000 nm is absorbed by mitochondria and raises their energy output.
Gromeus has covered the two-week UCL trial in people over 40 and a follow-up where one morning session helped for a week. The trial was small and short, included only healthy volunteers, and did not test any eye disease. The university also noted that the torches were built for the study and that no torch on sale had the same specification.
Why red light lasers for children’s myopia raise safety concerns
Repeated low-level red light therapy (RLRL) is a different use of red light: a child looks into a desktop laser device to slow the eye growth that causes myopia. In a 2024 paper, optometry researchers Ostrin and Schill measured the light output of two of these devices, the Sky-n1201a and the Future Vision. The paper describes the usual schedule as three minutes twice a day, five days a week, for a treatment that can last years. The authors note that several studies report slower eye growth with the treatment.
The same paper found that three minutes of continuous viewing approached or exceeded the maximum permissible exposure (MPE), the highest light dose a laser safety standard allows for the retina. The authors write that this puts the retina at risk of light-induced chemical damage and heat damage. For the Sky-n1201a, the paper calculated that the chemical damage limit is reached after 0.55 to 7 seconds, depending on pupil size (2 to 7 mm). For the Future Vision, the same calculation gave 50 to 625 seconds.
The paper also describes a 2023 case report by Liu and colleagues: a 12-year-old whose retina was damaged after five months of the therapy. According to the same paper, the child’s best corrected vision fell from 6/6 to 6/9 (20/20 to 20/30 in US notation), and scans showed damage at the center of the retina. The paper reports that vision partly recovered, to 6/7.5 (about 20/25), three months after treatment stopped. Ostrin and Schill advise clinicians to be cautious with the therapy in children until safety standards are confirmed.
Update (2025): a JAMA Ophthalmology study of 99 children with myopia found fewer cone cells near the center of the retina in those who had used RLRL for at least a year. Cone cells are the light sensors that handle color and sharp vision. According to the same study, 11 eyes showed abnormal bright spots near the fovea (the spot of sharpest vision), and one child had small cyst-like changes that cleared three months after stopping. The study looked back at existing records and compared users with non-users, so it shows a link and cannot prove that the light caused the changes.
What this means before using a red light device on the eyes
The UCL trial used a low-cost LED torch in healthy adults, while the myopia devices use lasers in children. Results from one setting cannot be assumed to apply to the other. Neither line of research tested the red light panels and masks sold for home use, so their effect on the eyes is unknown based on available sources.
Parents offered RLRL for a child can ask the eye doctor which device is used, how its output compares with laser safety limits, and how the retina will be checked during treatment. For another popular approach to nearsightedness, Gromeus looked at Endmyopia, a program that claims to reverse nearsightedness.
Sources and related information
UCL – Declining eyesight improved by looking at deep red light – 2020
The university release describes the 670 nm LED torch trial in 24 adults and its color and dim-light results. The underlying paper is Shinhmar et al., Optically improved mitochondrial function redeems aged human visual decline, The Journals of Gerontology: Series A, 2020.
Ophthalmic and Physiological Optics – Red light instruments for myopia exceed safety limits – 2024
Ostrin and Schill measured two red light myopia devices against laser safety limits and summarized the 2023 retinal damage case reported by Liu and colleagues in JAMA Ophthalmology (DOI 10.1001/jamaophthalmol.2023.1548).
JAMA Ophthalmology – Cone density changes after repeated low-level red light treatment in children with myopia – 2025
Liao and colleagues compared retinal images of children who used RLRL with non-users, the source of the 2025 update on cone cells.
