Are you unsure of the importance of prescribing and wearing protection against high energy blue light exposure? With a number of studies published in the past decade about the potential dangers of prolonged exposure to high energy blue light from computer and screen time, blue blocking technology has been a buzz word in the optical industry. While we know excess exposure to blue light can cause fatigue, light sensitivity, and even difficulty sleeping, some studies additionally report that high levels of exposure could potentially cause toxicity within our retinal cells - increasing the risk of blinding eye diseases like macular degeneration. The debate is ongoing since only animal studies have been done to date linking this potential for retinal toxicity, so as an optometrist both my colleagues and I must decide if we prescribe blue blocking lens technology for visual performance reasons in addition to the possible health risks. Can blue blocking eyewear make a marked difference in visual performance for patients with a history of prior vision loss from eye disease? A March 2017 study published in BioMed Central Ophthalmology showed exciting results about the power of blue blocking technology!
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| This study caught my eye because I personally wear Transtions XTRActive in brown and Crizal Prevencia in my glasses. You can see the purplish reflections here off my Prevencia blue blocker coating when I'm working on Eyedolatry! |
The Set Up
The study looked at 60 patients with a known history of vision loss. Half of the patients had central vision loss (called central scotoma - meaning they had a missing area of vision within 5 degrees of the fovea), and the other half had peripheral scotoma (vision loss outside of 5 degrees from the fovea). These patients had conditions ranging from age related macular degeneration, Stargardt macular dystrophy, diabetic retinopathy, glaucoma, Retinitis Pigmentosa, ocular albinisim, and degenerative myopia. Patients' vision was assessed both on high contrast black lettering on a white background (a traditional Snellen chart), low contrast (using the MARS contrast sensitivity chart) and with Glare Testing (where a light was shone at the patient while checking acuity to mimic the affect of oncoming glare on vision). Patients' vision was checked with their normal best corrected vision, and then the patients were fit with photochromic Transitions XTRActive lenses with Crizal Prevencia blue blocker anti-reflective coatings. Transitions XTRActive lenses block 88-95% of blue light at the high energy blue wavelength of up to 430 nm when activated. Crizal Prevencia filters 20% of high energy blue wavelength light indoor and out.
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| Glare Testing simulates the affect of oncoming glare on visual ability via |
The Results
Wearing the Transitions XTRActive and Crizal Prevencia blue blocking glasses improved visual performance on all three types of vision test for patients in both categories of vision loss.
- For patients with central scotoma the average best corrected visual acuity increased from 0.30 ± 0.20 to 0.36 ± 0.21 decimals for black on white letters. For patients with peripheral scotoma the average best corrected vision increased from 0.44 ± 0.22 to 0.51 ± 0.23 decimals for black on white letters.
- Significant increases were also detected in contrast sensitivy test: the letter count for the Mars test increased from 26.7 ± 7.9 to 30.06 ± 7.8 in patients with central scotoma and from 31.5 ± 7.6 to 33.72 ± 7.3 in patients with peripheral scotoma.
- Glare was also significantly reduced, as shown by the results of the glare testing: the letter count increased from 20.93 ± 5.42 to 22.82 ± 4.93 in patients with central scotoma and from 24.15 ± 5.5 to 25.97 ± 4.7 in patients with peripheral scotoma.
The study took things one step further to see if yellow filter lenses (which would block 100% of blue light) would give better visual performance versus the combination of Transitions XTRActive and Crizal Prevencia. The blue blocker lenses provided patients with statistically significant better visual performance on all three vision tests when compared to yellow filter lenses. Interestingly, there was no statistically significant difference in performance of patients wearing yellow tinted lenses compared to wearing normal, clear eyewear. Study designers theorize that due to the gross color change caused by the yellow filters, less benefit was seen by these patients with vision loss who are already more sensitive to the impact of low light levels reaching the retina. No patients tested complained about color vision distortion using the blue blocker glasses, as opposed to yellow filters which did cause vision complaints from most (yellow filters innately make everything in the field of vision yellow in appearance).
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| Yellow tinted lenses have an overt color skew to everything you see, which was less effective in improving visual performance for patients with vision loss in this study. via |
We still are just beginning to understand if our increased exposure to indoor levels of high energy blue light could increase our risks of blinding eye disease like macular degeneration, or if wearing blue blocking lenses could in anyway be protective against disease progression. What this study does show definitively is that blue blocking lens technology can functionally improve vision in patients with eye disease, even if we don't yet have the science to fully conclude if it can help protect them from further vision loss. If we can provide our patients with better visual performance, with better ability to see even in low contrast situations like driving at night or in the face of glare like oncoming headlights, the power of this technology truly speaks for itself.
Of important note: this study was not funded by Essilor (the makers of both Transitions XTRActive and Crizal Prevencia). You can access the full findings here.
