Blue Light-filtering Lenses Research Articles

Blaulichtfilter und deren Auswirkung auf den Pupillenlichtreflex

Purpose. The increasing exposure to artificial blue light sources has spawned an equal interest in spectacle lenses that protect against this potentially harmful proportion of light. This study compared the performance of different blue light filtering spectacle lenses and investigated whether a reduction in blue light transmission affects light-dependent physiological processes. Material and Methods. The wavelength-specific transmission of various spectacle lenses was determined by spectrometer and the influence of the lenses on the PIPR (Post Illumination Pupil Response) was evaluated. Thirty-six eyes of 18 adults (20 - 30 years) were measured by monocular, direct chromatic pupillometry with and without blue light filtering lenses. The modified pupillometer (PupilX from Albomed GmbH) with red and blue stimulation was used with a pupil exposure time of 30 seconds (darkness: 1 s; light stimulus: 1 s; darkness: 28 s). Results. In the main action spectrum of the blue light hazard (400 nm ≤ λ ≤ 500 nm), the transparent blue light filter showed lower absorption compared to “comfort- and wellness” lenses of filter category 1 (absorption: 19.60 % to 25.27 % and 65.04 % to 97.43 %). In the early and late phase of the post illumination pupil reflex (PIPR) after a blue light stimulus, we detected a significantly smaller area under the curve (p < 0.001), a larger normalized pupil diameter (p < 0.001), and a larger curvature index in an exponential interpolation (p < 0.001) when the “comfort- and wellness-” lenses were used. Conclusion. Blue light filtering lenses have been shown to reduce the transmission of blue light and thus can minimize the risk of blue light exposure. By simultaneously reducing the stimulation of intrinsic photosensitive retinal ganglion cells (ipRGCs), light-modulated physiological processes such as circadian regulation could be altered. The use of “comfortand wellness” lenses showed a significant change in the PIPR. An influence by transparent, blue-light filtering spectacle lenses could not be detected. Keywords Blue light filtering spectacle lenses, blue light hazard, chromatic pupillometry, intrinsically photosensitive retinal ganglion cells, circadian rhythm

The effect of blue light filtering lenses on speed perception

Blue-light filtering lenses (BFLs) are marketed to protect the eyes from blue light that may be hazardous to the visual system. Because BFLs attenuate light, they reduce object contrast, which may impact visual behaviours such as the perception of object speed which reduces with contrast. In the present study, we investigated whether speed perception is affected by BFLs. Using a two-interval forced-choice procedure in conjunction with Method of Constant Stimuli, participants (n = 20) judged whether the perceived speed of a moving test stimulus (1.5–4.5°/s) viewed through a BFL was faster than a reference stimulus (2.75°/s) viewed through a clear lens. This procedure was repeated for 3 different BFL brands and chromatic and achromatic stimuli. Psychometric function fits provided an estimate of the speed at which both test and reference stimuli were matched. We find that the perceived speed of both chromatic and achromatic test stimuli was reduced by 6 to 20% when viewed through BFLs, and lenses that attenuated the most blue-light produced the largest reductions in perceived speed. Our findings indicate that BFLs whilst may reduce exposure to hazardous blue light, have unintended consequences to important visual behaviours such as motion perception.

Impact of blue light filtering glasses on computer vision syndrome in radiology residents: a pilot study.

Computer vision syndrome (CVS) is an umbrella term for a pattern of symptoms associated with prolonged digital screen exposure, such as eyestrain, headaches, blurred vision, and dry eyes. Commercially available blue light filtering lenses (BLFL) are advertised as improving CVS. Our pilot study evaluates the effectiveness of BLFL on reducing CVS symptoms and fatigue in a cohort of radiologists. A prospective crossover study was conducted with ten radiology residents randomized into two cohorts: one wearing BLFL first then a sham pair (non-BLFL), and the other wearing a sham pair first then BLFL, over two weeks during normal clinical work. Participants filled out a questionnaire using the validated computer vision syndrome questionnaire (CVS-Q) and the Swedish Occupational Fatigue Inventory (SOFI). The majority of symptoms [11/16 (68.8%) and 13/16 (81.3%) symptoms on the CVS-Q and SOFI, respectively] were reduced (i.e., symptoms less severe) with the BLFL compared to the sham glasses. Females rated symptoms of sleepiness and physical discomfort in the SOFI, and overall CVS-Q, as more severe. Postgraduate year (PGY)-2 residents rated all symptoms as more severe than PGY-3/4s. BLFL may ameliorate CVS symptoms. Future studies with larger sample sizes and participants of different ages are required to verify the potential of BLFL.

In focus: Chasing away the blues

Blue light filtering lenses have been introduced by most of the major manufacturers but early claims about the potential damage certain wavelengths of the blue light could cause have been scaled back dramatically. Optician takes views from around the sector and hears how one Bath practitioner has sought to bring some clarity. Chris Bennett reports.

Blaufilter-Intraokularlinsen – derzeitige Datenlage

Data from both experimental and epidemiological trials have suggested a potential correlation between extraction of the natural lens associated with exposure to photo-oxidative stress to the retina and a progression of diseases such as AMD. A fundamental factor could be the unchecked exposure to blue light. This is why in the past years so-called blue light-filtering intraocular lenses have been implanted to serve as a protection to the retina. The following contribution is based on a data base research (Pub Med, National Library of Medicine, USA) and summarises information currently available on the use of blue light-filtering lenses. Experimental modeling has shown that, compared to regular UV lenses, blue light-filtering lenses block a considerable part of blue light transmission to the retina and reduce damage to retinal cells and production of inflammatory markers such as VEGF. The majority of the clinical data demonstrate that blue light-filtering lenses are compatible in terms of visual acuity, contrast sensitivity and colour perception as well as patient-rated quality of vision. But a few additional studies report reduced contrast sensitivity and limitations in mesopic vision.This is also true for the circadian rhythm. However, the evaluation of this parameter in connection with blue light-filtering lenses has only been done on a theoretical basis. Long-term data showing that blue light-filtering lenses actually do reduce the incidence of retinal diseases such as AMD are currently not available.

Preferring Blue Light-filtering Lenses

The spectral permeability of intraocular lenses (IOL) determines the known “blue hazard” for the retina, which affects the development of age related macular degeneration (AMD). On the one hand, the blue hazard causes irreversible damage to the blue receptors. Further, the yellow lipofuscins that are deposited during the daily partial replacement of the outer segments of the photoreceptors on the retina tend to fluoresce in the blue light. This light energy activates the oxygen that is present, resulting in the formation of highly active, toxic radicals (reactive oxygen species, ROS). These can be warded off only to a degree. The eye protects itself against UV damage because the lens absorbs UV light and may thus develop a cataract. The age related yellowing of the lens is akin to an increase in the blue protection and makes sense physiologically because with increasing age the risk of retinal damage increases owing to the imbalance of ROS lipofuscins and repair mechanisms. The blue hazard that is caused by a colorless intraocular lens is clearly in excess of that of a 4 year old child (!) and, because it happens to a retina that is already weakened, it increases the risk of AMD. For the violet and blue spectrum, the blue-filtering intraocular lens imitates the permeability curve of the lens of a 50 year old. Although several questions remain unanswered (1), the blue-filtering lens should be preferred and colorless lenses used only for particular indications. Further, the permeability curve of sunglasses is crucial for the risk associated with light and the progression of AMD (2, 3).