Blue-Blocking Technology May Provide Some Benefits, But Research Is Inconclusive

During the past decade, advertising has successfully convinced many eye care professionals and patients that blue-blocking technology provides a solution for digital eye strain and protects against ocular pathology. While there may not be any harm in wearing lenses designed to reduce high-energy visible blue light exposure, and some studies may even suggest that these products can provide some benefit for patients, these claims have confused clinicians and blurred the line between commercialism and factuality. 

Research shows that blue light can inhibit melatonin secretion and enhance adrenocortical hormone production, which can affect hormone balance, systemic health, and sleep quality.¹ While these findings may lend credibility to associations between blue light and mood improvement or sleep cycle regulation, there are no conclusive investigations proving that blue light exposure damages the retina or contributes to ocular pathology.²

Blue Light Exposure and Cataracts

Ultraviolet (UV) light exposure is a known risk factor for cataract development, and since high-energy visible blue light is closest to this wavelength on the electromagnetic spectrum, some may reason that artificial sources emitting this light may increase cataract risk. Research has shown an association between blue light and increased reactive oxygen species (ROS) production in the mitochondria of lenticular epithelial cells, which may lead to cataract development due to oxidative stress.³ One investigation appears to lend credibility to the dangers of blue light exposure by showing that short wavelengths of light cause cataracts in porcine eyes, creating a concern that high-energy visible blue light emitted by light emitting diode (LED) illuminants could pose a danger to human eyes.⁴ However, a failure to consider exposure time and investigate these effects in human eyes limited the investigation’s findings. 

A 2021 study using transparency measurements and dark field image analysis suggests that blue light is more likely to cause a cataract than UVB and UVA radiation.⁵ However, the study authors acknowledge that most of the current scientific literature diverges from these findings.⁵ 

Macular Degeneration and Blue Light

The intense metabolic activity occurring within the retina makes it an area of interest for research investigating the effects of blue light exposure. The high volume of oxygen present in the retina can make the retinal pigment epithelium (RPE) vulnerable to oxidative damage that results in pathological changes associated with age-related macular degeneration (AMD). 

Considering wavelength is important when discussing the potential adverse effects of blue light exposure, as some experimental models suggest that exposure in the 470 to 490 nm range may be less damaging to the eye compared with blue light in the 400 to 460 nm range.⁶ A 2023 study using in vivo and in vitro experiments with mice shows that long-term blue light exposure causes excess oxidative stress and severe damage to retinal tissues, especially RPE cells, with harmful effects peaking at 440 nm.⁷ These findings highlight a concern for individuals undergoing cataract surgery and blue-light-filtering intraocular lenses (IOLs) have been developed to limit blue light exposure. 

A 2018 investigation explored postoperative contrast sensitivity, color discrimination, macular pigment optical density (MPOD), the proportion of eyes with a pathological finding at the macula, daytime alertness, reaction time, and satisfaction among patients who underwent blue-light filtering IOL vs non‐blue‐light filtering IOL implantation following cataract surgery.⁸ The report found no significant difference in distance BCVA between participants implanted with the 2 IOLs (mean difference, 0.01 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.03-0.02; P =.48) and little evidence that a blue-light-filtering IOL reduced the incidence of developing late-stage AMD at 3 years, or any stage of AMD at 1 year.⁸ 

Overall, research has failed to establish an association between implanting a blue-light-filtering IOL during cataract surgery and reduced incidence or progression of neovascular AMD.⁹ Since these IOLs do not provide improvements in short-term contrast sensitivity, and their ability to preserve macular health or alter the risks associated with AMD has not been proven, their implantation during cataract surgery has been largely discontinued.^8,10  

A narrative review of the literature between 2010 and 2022 concludes there is little evidence blue-blocking technology protects against retinal degeneration, but a small sample size, limited follow up, and variances in wavelength and stimuli between studies are barriers to reaching a conclusion.¹¹ 

While both animal and cell culture model studies show potential retinal phototoxicity resulting from blue light exposure, the toxicity depends on wavelength, intensity, and duration of exposure, and there are no international standards regulating the amount of blue light reduction needed to prevent ocular damage.¹² Since individual susceptibility to blue light damage varies significantly, determining the risk associated with repeated exposure to blue light in the etiology of AMD is difficult.⁶ 

Glaucoma Incidence and Blue Light

An increase in glaucoma incidence among younger individuals with myopia has created a concern that it may be linked with blue light exposure. As blue light induces mitochondrial apoptosis in retinal ganglion cells, causing optic nerve damage, it may be a factor.¹³ 

While a 2023 study suggests that blue-light-filtering IOLs were associated with more favorable glaucoma outcomes compared with non blue-light-filtering IOLs, there were no significant differences in outcomes among individuals with pre existing glaucoma.¹⁴ 

Blue-Blocking Technology and Digital Eye Strain

Dry eye, fatigue, headaches, and blurred vision are common symptoms of computer vision syndrome, and clinicians often suggest lenses with blue-blocking technology to their patients, hoping it will help them manage their end-of-day symptoms. Digital eye strain, however, is multifactorial and likely not the result of blue light exposure, but reduced blinking, tear film disruption, uncorrected refractive error, oculomotor dysfunction, and other causes.² 

A 2020 investigation found that neutral density filters and blue-blocking technology demonstrated similar efficacy for reducing digital eye strain symptoms.¹⁵ Other research suggests that managing  ocular surface issues and an optimal screen environment that accounts for distance, lighting, and positioning, has the most impact on reducing patient symptoms.¹⁶ One investigation assessing orbicularis oculi muscle activity examined visual symptoms among individuals with and without blue blocking spectacles found that blue-blocking technology did not alleviate digital eye strain symptoms.¹⁷ 

Blue Light’s Effect on Systemic Health

Blue light stimulates melatonin secretion in the pineal gland, which can increase or decrease cortisol expression, depending on time of day, and regulate human circadian rhythm. Blue light, in particular, regulates the body clock and promotes alertness, memory, and cognition. Excessive blue light exposure may stimulate the brain and directly affect sleep quality. While all wavelengths of light can suppress melatonin, blue light has been found to shift circadian rhythm by twice as much as green light.¹ 

As with other blue-blocking technology, research is inconclusive as to whether blue-light-filtering displays on smartphones affect melatonin levels and tear film stability. Research also suggests that brightness may have a greater effect on melatonin suppression than blue light exposure.¹² 

Melatonin dysfunction has been implicated in the development of type 2 diabetes, immune responses, cancer, and blood pressure disorders, and nocturnal melatonin suppression may lead to other negative health outcomes. Time of day is an important consideration when recommending blue-blocking technology to patients — daytime blue light exposure may have positive effects, while early evening or nighttime exposure may negatively affect circadian system and sleep.¹⁰

Communicating Realistic Expectations With Patients

When a majority of adults in the US use the internet to seek medical advice and may believe the information to be comparable or superior to information provided by their doctors, optometrists must take the initiative to improve communication skills and keep abreast of the most current evidence-based research. Even content posted by reputable healthcare or government organizations shows quality, accountability, and readability deficiencies for reporting the effect of blue light on ocular health, according to a 2023 investigation.² As lens manufacturers continue to promote their products with unsubstantiated claims and websites continue to publish information that may potentially, albeit often unintentionally, mislead consumers, optometrists must take an active role in educating patients on the facts vs myths for blue-blocking technology. A lack of high-quality clinical trials assessing the efficacy of these products continues to make this a challenge.² However, in the ever-changing world of eye care, regularly reviewing the scientific literature can assist optometrists in making evidence-based recommendations for their patients.