In a new study published in JAMA Ophthalmology, investigators conducted a randomized clinical trial (RCT) to examine the effect of low-level red light (LLRL) on spherical equivalent error (SER) and axial length (AL) in children with myopia.
Give me some background on LLRL.
LLRL is an emerging treatment for myopia that works by concentrating a band of light (typically 650 nm) to irradiate the retina.
While previous research has shown promising results for LLRL in slowing myopia—with no damage to the retina—the researchers in this study noted that it is unclear whether this therapy could be effective for children.
See here for our previous coverage on LLRL.
Now, talk about this new study.
This study was a single-masked, single-center, RCT. Participants were recruited from August 12 to September 3, 2021, and underwent qualification assessment at the Tongren Hospital in Beijing, China.
The participants in the study were randomly assigned to one of two groups at a 1:1 ratio:
- LLRL group
- Control group
Tell me more about these participants.
Investigators recruited a total of 336 children (aged 6- 12), diagnosed with myopia, emmetropia, and low hyperopia.
The participants were comprised of:
- 90 (53.6%) female patients in the treatment group
- 86 (51.2%) female patients in the control group
- 224 individuals with low to moderate myopia
- 112 individuals with emmetropia or low hyperopia
And the inclusion criteria?
The inclusion criteria were as follows:
- Aged 6 to 12
- Cycloplegic spherical equivalent error (SER) of between -6 diopters (D) and 3 D in both eyes.
- For participants without myopia, the change in SER was -0.75 D or less in the last year
- Astigmatism of 2.5 D or less
How was the study conducted?
Participants in the treatment group were given a headset that emitted 650 nm single-wavelength light. The participants received this treatment for 3 minutes, twice a day (BID), 4 or more hours apart.
Note: Participants with myopia in the treatment and control groups were allowed to wear single-vision spectacle lenses.
Now the findings: What were the changes in SER?
Mean (SD) changes in SER were:
- At 6 months:
- 0.15 (0.16) D for the LLRL group
- −0.26 (0.21) D for the control group
- Difference, −0.41 D; 95% Confidence interval (CI), −0.48 to −0.34 D; P < .001
- At 12 months:
- 0.24 (0.27) D for the LLRL group
- −0.65 (0.33) D for the control group
- Difference, −0.89 D; 95% CI, −0.95 to −0.83 D; P < .001
And the changes in AL?
Mean (SD) changes in AL were:
- At 6 months:
- -0.06 (0.08) mm for the LLRL group
- 0.13 (0.12) mm for the for the control group
- Difference, 0.19 mm; 95% CI, 0.16 to 0.22 mm; P<.001
- At 12 months:
- −0.11 (0.10) mm for the LLRL group
- 0.26 (0.16) mm for the control group
- Difference, 0.37 mm; 95% CI, 0.34 to 0.40 mm; P < .001
Any other findings?
The results showed no retinal changes in the treatment or control group.
Limitations?
The authors stated that, as the study design was a single-central trial, the results may not be generalizable to other areas of China, Asia, or the rest of the world.
Additionally, they added that the participants in the study were not masked and the follow-up duration was only 1 year.
Lastly, the investigation took place during the COVID-19 pandemic; thus, it was unclear if factors during that period influenced the results (such as time spent outdoors and on digital devices).
Expert opinion?
The authors stated, “Confirmation of these findings at independent sites seems warranted, as well as determining whether these effects can be sustained with or without continued treatment and whether LLRL has any effect on pathological myopia.”
Take home.
The findings from the research suggest that daily use of 650-nm LLRL for 1 year may slow the progression of SER and AL without safety concerns identified.