Photostress Recovery Research Articles

Normative value of photostress recovery time among various age groups in southern India

Background: To determine the normative data and reference value for photostress recovery time (PSRT) following exposure of the macula to light, in various age groups within the Indian population.
 Methods: Cross-sectional observational study performed from November 2015 to July 2016 in the Bangalore district of Karnataka state in India. We examined a total of 1,282 eyes of 641 participants and included those with corrected distance visual acuity (CDVA) scoes lower than or equal to 0.4 Logarithm of the Minimum Angle of Resolution (LogMAR). We performed the photostress procedure under standard conditions using the same approach.
 Results: The mean ± standard deviation (SD) of the participants’ age was 32.04 ± 15.80, with an age range of 8 to 70 years. The PSRT in participants below 16 years and above 45 years of age were significantly different compared to the 16–25-year-old age group (P < 0.0001 for both). The PSRT values were significantly different between males and females in the reproductive age group (16 to 45 years old) (P < 0.0001), but not in the other age groups.
 Conclusions: The PSRT values were significantly different in children and older patients compared to the 16 to 25 years age group. We found that as age increased, PSRT increased significantly.

The association between macular pigment optical density and visual function outcomes: a systematic review and meta-analysis.

To conduct a systematic review and meta-analysis on data related to macular pigment optical density (MPOD) and visual function in adults with healthy eyes. MEDLINE®, Cochrane, and Commonwealth of Agriculture Bureau abstracts databases were searched for English-language publications between 1946 and August 2018. Included studies examined correlation of MPOD and visual function in adults with healthy eyes at all timepoints and all designs, except for case-control, case reports, and reviews. Visual function outcomes of interest included photostress recovery, contrast sensitivity, visual acuity, glare sensitivity/disability, and dark adaptation. Random effects model meta-analyses combined study-level correlation (r). Twenty-two publications were included. In meta-analysis MPOD was found to be significantly correlated with contrast sensitivity at 30' (two studies, summary r: 0.37; 95% CI 0.15, 0.56), and at 1° eccentricity with a spatial frequency of 7, 11, and 21 cpd (three studies, summary r: 0.31; 95% CI 0.06, 0.52), with photostress recovery at a 1° eccentricity with a moderate background, 10 cpd, and 16% contrast (two studies, summary r: -0.17; 95% CI -0.31, -0.02), and at 30' (four studies, summary r: -0.57; 95% CI -0.78, -0.24), and with glare disability at 30' eccentricity with a log scale at 460 nm (three studies, summary r = 0.47; 95% CI 0.32; 0.59). There were insufficient data for meta-analysis for other visual functions. Our review identifies a link between MPOD and visual function with significant correlations with photostress recovery, glare disability, and contrast sensitivity.

The Effect of a Photochromic Contact Lens on Visual Function Indoors: A Randomized, Controlled Trial.

SIGNIFICANCEPhotochromic soft contact lenses contain light-sensitive additives that allow them to darken when exposed to ultraviolet or violet light. One question, however, is whether the lenses influence vision indoors (minimally activated). In this study, we found that the minimally activated lenses improved many aspects of visual function under bright light.PURPOSEPhotochromic contact lenses were designed to darken when exposed to outdoor sunlight. The filtering that results improves visual function under bright light conditions. Not all bright light exposures occur outdoors. In this study, we tested whether a photochromic contact lens improved visual function under conditions where the lens was minimally activated (i.e., no more than it normally would be in an indoor environment).METHODSA subject-masked contralateral design was used comparing a photochromic contact lens randomized to one eye against a nonphotochromic contact in the other eye of the same subject. Sixty subjects (mean = 34.90 ± 11.24 years) were tested. The primary endpoints consisted of four visual function outcomes: photostress recovery, glare disability, glare discomfort, and chromatic contrast. Photostress recovery was quantified by measuring the time needed to recover visual acquisition of a grating target after 5 seconds of an intense xenon white flash exposure; glare disability was evaluated as the energy in a surrounding xenon white annulus necessary to veil a central grating target; and glare discomfort was assessed using bioimaging of the squint response. Chromatic contrast was measured as thresholds for a green-yellow (580 nm) grating target superposed on a blue (460 nm) background.RESULTSThe minimally activated photochromic contact demonstrated improved visual performance compared with the nonphotochromic control across all visual functions tested (P < .01).CONCLUSIONSEven under conditions of exiguous activation (e.g., as would be expected indoors or while driving at night), a photochromic contact will improve many of the more deleterious aspects of bright light.

Photostress Recovery Time in Males: Alcoholics vs Non Alcoholics

Photostress Recovery Time in Males: Alcoholics vs Non Alcoholics

The effects of light scatter when using a photochromic vs. non-photochromic contact lens

PurposeTo assess the visual effects of wearing both an activated and an inactivated photochromic contact lens, with a direct comparison to a non-photochromic contact lens worn in the fellow eye. This study focused on the visual effects of scatter quantified as the minimum distance between two points of light, and the diameter of the halo and starbursts that surround a bright white point source. Methods60 subjects (aged 18–65 years) were measured in a contralateral design where lens type was randomly assigned, one type to each eye. During activated testing, all visual measures of both study lenses were made while each eye was illuminated by a violet (λmax=365, half bandwidth 20nm) activator, which caused steady-state activation of the photochromic lens during the period of testing. Two-point thresholds were determined by measuring the minimum distance between two points of broadband xenon light. Glare geometry was measured using an aperture (∼4mm) that created a bright point source of light 45 inches from the plane of the eye. Between the point source and subject, a centering precision caliper was used to measure lateral spread of halos (diffusion around the source) and visual spokes. The head was stabilized using an adjustable head-rest assembly and the eye was aligned and monitored with a bore camera. ResultsCompared to the non-photochromic lens, and based on the stimulus conditions used in these measurements, the activated and inactivated photochromic lens reduced the light spread using the two-point threshold technique by 32% and 19% respectively; the diameter of the halos were reduced by 44% and 16% respectively; and the spokes were narrowed by 39% and 20% respectively. Based on 95% confidence interval testing, these effects were all statistically significant (p<0.05). ConclusionsThese results are consistent with previous data showing that soft contact lenses with a photochromic additive can improve many aspects of visual function, consistent with their level or activation. Our past data focused on visual function under bright light conditions (e.g., glare disability, discomfort, photostress recovery and chromatic contrast) with an activated photochromic. In this study, we found differences even in the inactivated state, using less intense stimuli (10cd/m2 at the source). This suggests that the photochromic lens improves the effects of light scatter even at lower luminance.

Practical application of ophthalmic nutraceuticals in patients with dry form of age-related macular degeneration

To conduct a placebo-controlled clinical monitoring of visual functions in patients with dry AMD while taking a drug Complex that corresponds to the AREDS 2 formula. The study included 90 people in 3 equivalent parallel groups, two of which were represented by patients with AMD who took the Complex for 3-6 months or Placebo for 3 months. The third group included healthy subjects of the same age. In addition to standard eye examination, participants underwent evaluation of the macular pigment optical density (MPOD), spatial-frequency contrast sensitivity (CS), photostress test, and reading parameters on the Salzburg Reading Desk device. The changes of blood plasma antioxidant activity (AOA) were also evaluated in the main group. By day 90 of the study, patients of the main group showed statistically significant (p<0.001) growth of MPOD from 0.24±0.13 to 0.32±0.1, reduction of photostress recovery time from 68.2±17.8 to 57.3±17.5 seconds, improvement of high-spatial-frequency CS - from 25.0±8.2 to 30.6±6.8 dB, increase of near visual acuity logMAR from 0.22±0.04 to 0.19±0.03 and reading speed, and decrease of reading mistakes. Statistically significant (p<0.05) reduction of in AOA was seen during the observation period from 1.52±0.16 to 1.68±0.16. Patients of the main group who received the Complex for 180 days demonstrated additional improvements of visual functions. The drug Complex corresponding to the AREDS 2 formula contributes to a significant increase in MPOD, improvements of visual functions and overall antioxidant status of patients, which confirms the feasibility of its use in patients with dry AMD.

The Effects of Blue Light-Filtering Intraocular Lenses on the Protection and Function of the Visual System.

Filtration of high-energy short-wave visible light (blue light) to improve vision and protect against damage has evolved both in aquatic animals and terrestrial species. In humans, pigments in the inner layer of the macula absorb wavelengths between 400 and 520 nm and function to improve visual performance. In patients who undergo cataract surgery, replacing cataractous lenses with artificial intraocular lenses (IOLs) that do not mimic normal healthy adult lenses could result in preventable negative visual effects, including glare disability. Blue light–filtering (BLF) IOLs were designed to filter short-wave light in addition to ultraviolet light and mimic the natural crystalline lens. Current studies indicate that BLF IOLs may provide protection from blue light–induced retinal damage and slow the development and progression of age-related macular degeneration. Additionally, BLF IOLs have been shown to improve chromatic contrast, reduce photostress recovery time, reduce glare disability and discomfort, and generally improve visual performance under glare conditions. Although a number of concerns have been raised about the relative risks versus the benefits of BLF IOLs, recent studies reported no adverse effects on visual function or contrast under photopic conditions, no long-term effects on color vision, and no detrimental effects on circadian rhythms with BLF IOLs. Based on the current understanding of the field, evidence suggests that BLF IOLs would be returning the eye to a more natural state compared with non-BLF lenses.

A contra-lateral comparison of the visual effects of a photochromic vs. non-photochromic contact lens

PurposeTo compare the effects of a photochromic contact lens vs. a non-photochromic control lens on visual function. MethodsA subject-masked, prospective contralateral eye design was used. Sixty-one subjects were enroled based on age (using a 2:1 allocation ratio for ages 18–39 and 40–65 years, respectively). The study lenses were senofilcon A with photochromic additive (Test) that filtered over the entire lens, compared to a non-photochromic Control with no tint. The Test lens was partially activated during testing with a steady-state transmittance of approximately 62%. Eligible subjects were tested using both study lenses, with Test and Control lens randomized by eye. Five visual function outcomes were tested: photostress recovery (PSR), glare disability (GD), glare discomfort (GDC), chromatic contrast (CC) and vernier acuity (VA). Iris colour and macular pigment density were assessed as control variables. PSR was measured as the time needed to recover sight of a target after an intense xenon flash exposure; GD was evaluated as the energy needed to veil a central target by a surrounding xenon annulus; GDC was measured using bio-imaging of the squint response and by self-report using a 9-item Likert scale; CC was measured as thresholds for a yellow grating target superposed on a 460-nm background; VA was determined by measuring vernier offsets of light lines through apertures. ResultsBased on our stimulus conditions, PSR was 43% faster using the Test vs. the Control. The eye wearing the Test had 38% less squint (GDC) compared to the Control. GD was improved by 36% in the Test vs. Control and CC was enhanced by 48% with the Test. There was no significant difference in VA. ConclusionsThere was a beneficial influence on visual function when comparing the photochromic with the non-photochromic contact lens. This benefit was seen specifically with respect to PRT, GDC, GD and CC thresholds.

An Alternative Psychophysical Diagnostic Indicator of the Aging Eye.

Purpose Impaired adaptation to changes in lighting levels as well as mesopic visual function is a common complaint in those over the age of 65. The use of photostress is a well-established method to test the adaption rate and the response of the visual cycle. In this study, we test visual function recovery to mesopic luminance stimuli following a long duration photostress in young and elderly subjects. If successful in strongly differentiating aging macular function, these methods may also be useful in the study of pathologies such as age-related macular degeneration. Methods A group of 12 older normal subjects (mean age 75.1 ± 4.79) and a control group of 5 younger normal subjects (mean age 26.2 ± 4.19) were subjected to macular photostress using the OraLux photostress system. The OraLux system provides a diffuse light source bleaching 84% of cone photopigment while maintaining an exposure safety factor of 200 times less than the maximum safe exposure. After each photostressing session, macular recovery was tracked using a foveal, variable contrast, flickering stimulus of mean luminance in the high mesopic range. Recovery was tracked for 300 seconds. The endpoint was time to recovery to each individual's baseline sensitivity as determined by two static sensitivity trials prior to photostress. Results Proportional hazards analysis of recovery time yielded a statistically significant difference between the older group and the young group (HR = 0.181; p=0.0289). The estimated hazard ratio of 0.181 indicates that older subjects return to baseline at less than one-fifth the rate of younger subjects. The hazards ratio remained statistically significant after adjusting for visual acuity (HR = 0.093; p=0.0424). Conclusion Photostress recovery of flicker sensitivity under mesopic conditions is a strong differentiator of aging macular function. This agrees with subject-reported complaints in reduced luminance conditions after exposure to bright lights such as night driving. The qualitative similarity between the aging retina and changes in early AMD suggests that flicker recovery following photostress may be useful as a surrogate endpoint in AMD clinical trials.

Effect of central hole location in phakic intraocular lenses on visual function under progressive headlight glare sources

To analyze the effect of the central hole location in the V4c implantable collamer lens (ICL) on the quality of vision, including progressive headlight glare simulation and quality of life. IOBA-Eye Institute, Valladolid, Spain. Case series. The central hole location was determined by slitlamp and dual Scheimpflug imaging for 6months or more postoperatively. The visual acuity, mesopic contrast sensitivity, halogen glare contrast sensitivity, xenon glare contrast sensitivity, photostress recovery time after glare, de Boer scale, and Quality of Life Impact of Refractive Correction (QIRC) questionnaire results were evaluated. Multiple regression models were used to analyze the effect of the central hole location on parameters using the pupil center and visual axis as references based on Cartesian and polar coordinates. The safety index was 1.13 and the efficacy index, 1.12. Under all testing circumstances, central hole decentration did not affect the visual acuity or contrast sensitivity. With the visual axis as a reference, worse QIRC values were associated with greater upward central hole displacement (P=.03) and a lower polar angle value (P=.008); also, halogen glare discomfort was greater with a higher radius (P=.04). Using the pupil center as a reference, greater nasal central hole decentration was associated with longer xenon glare photostress recovery time (P=.002). Implantation of the ICL with a central hole yielded excellent visual outcomes, even under increasing glare sources, regardless of the hole's location. However, hole decentration might affect patient-perceived quality of life, bothersome halogen glare, and longer xenon glare photostress recovery time. Such complaints after the early postoperative period might be managed with discrete ICL centration if the central hole is decentered upward or nasally.

Modeling macular pigment optical density effects on photopic and scotopic vision in degraded visual environments

The macular pigment (MP) is an accumulation of the carotenoids lutein, zeaxanthin, and mesozeaxanthin in the central retina. These are derived from dietary sources. MP absorbs light in the 400- to 520-nm range. Consequently, the MP is a spectral filter over the photoreceptors, reducing the effects of internally scattered light and attenuating the short wavelength component of natural sunlight. The average MP optical density (OD) is about 0.2 to 0.6 log units depending on the sample population, whereas the range of MPOD is reportedly 0 to 1.5 log units. Some people can increase their MPOD by increasing their consumption of lutein, zeaxanthin, and mesozeaxanthin, and this may be important for vision in degraded visual environments (DVE). Specifically, nutritional interventions and dietary supplements have produced statistically significant enhancements under laboratory conditions in visual tasks, such as visibility through haze, low contrast target detection, contrast sensitivity, glare resistance and recovery, photostress recovery, dark adaptation, mesopic sensitivity, and enhanced reaction times. The question is whether these enhancements are operationally meaningful or not. The present paper begins to address the question by modeling MPOD effects on the visibility to low contrast photopic and scotopic targets seen under a range of DVE over realistic distances that incorporate atmospheric filtering. Specific model parameters include luminance, target contrast, spectral content, and distance. The model can be extended to estimate the efficacy of MPOD effects on target detection, discrimination, and standoff distances.

An Investigation of the Role of Macular Pigment in Attenuating Photostress through Comparison between Blue and Green Photostress Recovery Times

ABSTRACTPurpose: Photostress recovery time (PSRT) is the time required for the macula to return to its normal functioning after the bleaching of cone photopigments due to light exposure, usually white. This work investigates the role of macular pigment (MP) as an optical filter that attenuates photostress by analyses of PSRT at different wavelengths.Methods: Thirty-nine subjects (19–28 years) were exposed to blue/green photostress varying in irradiance. During photostress, pupil constriction (Cp) was measured. Twenty-seven subjects (20–27 years) were exposed to white photostress. After 25 s of photostress, the time (PSRT) required to read correctly a 0.2 logMAR letter was measured. Correlation was studied between PSRT, CP, and irradiance. Statistical significance of differences between PSRTs was evaluated at Log(irradiance(quanta s−1 cm−2)) = 14 by Student’s t statistics.Results: Cp and PSRT were found linearly correlated to Log(irradiance) for blue, green, and white. At Log(irradiance(quanta s−1 cm−2)) = 14, blue and green mean PSRTs resulted different (p < 0.001) with 3.8 ± 0.8 s and 6.7 ± 1.7 s, respectively. After correcting irradiance for the optical absorption of MP, mean blue PSRT became 6.6 ± 0.8 s, at the logarithm of MP-corrected irradiance in quanta s−1 cm−2 equal to 14 (p = 0.571 compared to green PSRT). For white light, at the logarithm of MP-corrected irradiance in quanta s−1 cm−2 equal to 14, mean PSRT was 7.5 ± 2.2 s, not significantly different from blue and green PSRT (p > 0.05).Conclusions: MP plays the role of an optical filter attenuating photostress. PSRT was substantially proportional to the number of incident photons corrected for the MP optical absorption, regardless of their wavelength.

Macular pigment is associated with glare-affected visual function and central visual field loss in glaucoma

AimTo evaluate the relationship between macular pigment optical density (MPOD) and glare disability in open-angle glaucoma.MethodsA cross-sectional analysis of baseline data (88 subjects; median age, 67 (range 36–84) years) collected...

Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure

The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased “screen time” (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months’ supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST. Forty-eight healthy young adults with at least 6 h of daily near-field ST exposure participated in this placebo-controlled trial. Visual performance measures included contrast sensitivity, critical flicker fusion, disability glare, and photostress recovery. Physical indicators of excessive screen time and sleep quality were assessed via questionnaire. MP optical density (MPOD) was assessed via heterochromatic flicker photometry. At baseline, MPOD was correlated significantly with all visual performance measures (p < 0.05 for all). MC supplementation (24 mg daily) yielded significant improvement in MPOD, overall sleep quality, headache frequency, eye strain, eye fatigue, and all visual performance measures, versus placebo (p < 0.05 for all). Increased MPOD significantly improves visual performance and, in turn, improves several undesirable physical outcomes associated with excessive ST. The improvement in sleep quality was not directly related to increases in MPOD, and may be due to systemic reduction in oxidative stress and inflammation.

Macular carotenoid supplementation improves disability glare performance and dynamics of photostress recovery.

BackgroundThe so-called macular carotenoids (MC) lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) comprise the diet-derived macular pigment (MP). The purpose of this study was to determine effects of MC supplementation on the optical density of MP (MPOD), repeated-exposure photostress recovery (PSR), and disability glare (DG) thresholds.MethodsThis was a double-blind, placebo-controlled trial. Fifty-nine young (mean age = 21.7), healthy volunteers participated in this study. Subjects supplemented their daily diet with either 10 mg L + 2 mg total Z (1 mg Z + 1 mg MZ; n = 24), 20 mg L + 4 mg total Z (2 mg Z + 2 mg MZ; n = 25), or placebo (n = 10) for 12 months. The primary outcome was a composite measure of visual performance in glare, defined by change in DG and PSR. Secondary outcomes included MPOD and visual fatigue. The primary endpoint for outcomes was 12 months. MPOD was assessed with customized heterochromatic flicker photometry. PSR times for an 8 cycle /degree, 15 % contrast Gabor patch target were determined after each of five successive exposures to intense LED lights. DG threshold was defined as the intensity of a ring of lights through which subjects were able to maintain visibility of the aforementioned target. Measures of all parameters were conducted at baseline, 6 months, and 12 months. Repeated-measures ANOVA, and Pearson product-moment correlations were used to determine statistically significant correlations, and changes within and between groups.ResultsMPOD for subjects in both supplementation groups increased significantly versus placebo at both 6- and 12-month visits (p < 0.001 for all). Additionally, PSR times and DG thresholds improved significantly from baseline compared to placebo at 6- and 12-month visits (p < 0.001 for all). At baseline, MPOD was significantly related to both DG thresholds (r = 0.444; p = 0.0021) and PSR times (r = -0.56; p < 0.001). As a function of MPOD, the repeated-exposure PSR curves became more asymptotic, as opposed to linear. The change in subjects’ DG thresholds were significantly related to changes in PSR times across the study period (r = -0.534; p < 0.001).ConclusionsIncreases in MPOD lead to significant improvements in PSR times and DG thresholds. The asymptotic shape of the repeated-exposure PSR curves suggests that increases in MPOD produce more consistent steady-state visual performance in bright light conditions. The mechanism for this effect may involve both the optical filtering and biochemical (antioxidant) properties of MP.Trial registrationISRCTN trial registration number: ISRCTN54990825. Data reported in this manuscript represent secondary outcome measures from the registered trial.

The effects of photochromic lenses on visual performance

BackgroundThe purpose of the current study was to evaluate the effects of filtering by an activated photochromic lens on visual performance in healthy adults. Glare disability, glare discomfort, heterochromatic contrast thresholds and photostress recovery time were assessed.MethodsA subject‐masked, randomised, cross‐over design was employed. Seventy‐five healthy adults were recruited, aged 19 to 73 years (mean = 45.61 ± 13.24 years). Visual functions were measured using three different photochromic lenses that were partially activated with a steady state transmittance of 63 per cent T (Gray1), 71 per cent T (Gray2), and 71 per cent T (Brown). These lenses were compared with a clear (92 per cent transmission) polycarbonate lens. Glare disability was assessed as the intensity of a white (xenon)‐light annulus necessary to obscure a central grating target. Heterochromatic contrast thresholds were measured as absolute thresholds for a monochromatic 570 nm target superimposed on a 460 nm circular background. Glare discomfort was quantified using bio‐imaging of the squint response as well as a Likert‐based self‐report scale. Photostress recovery time was recorded as the time necessary to regain sight of a grating target after intense light exposure. Glare discomfort and photostress recovery were only assessed for the Gray1 lens compared to placebo. Lens order was randomised between subjects and conditions.ResultsAll visual functions measured were significantly improved (p < 0.05) for all of the activated photochromic lenses tested versus the clear lens. In the glare disability and heterochromatic contrast conditions, numeric differences (p < 0.09) were also seen between each of the three different activated photochromic lens types. Glare discomfort and photostress recovery times were improved in the Gray1 condition, as quantified by both the squint and subjective responses (p < 0.05).ConclusionAdding filtering via a photochromic lens significantly increased subjects' abilities to cope with intense broadband and shortwave lighting conditions and to adapt back to normal viewing after being presented with an intense photostressor.

Relationship between macular pigment and visual function in subjects with early age-related macular degeneration

PurposeTo investigate the relationship between macular pigment (MP) and visual function in subjects with early age-related macular degeneration (AMD).Methods121 subjects with early AMD enrolled as part of the Central Retinal...

Photostress recovery time among commercial drivers in Nigeria

Photostress recovery time (PSRT) test is a simple technique used to assess the macular function. Prolonged recovery time is attributed to the delay in regeneration of visual pigments after being bleached with a bright light. In car drivers with macular degeneration, photostress effects from opposing cars may bleach retinal pigments and cause a dramatic drop in visual acuity. The study aims todetermine the prevalence of abnormal PSRT and the association of PSRT with age, visual function and driving safety among commercial drivers in Nigeria.A cross-sectional descriptive study was carried out in Ilorin metropolis, a city in north central Nigeria.Of the estimated 4,729 registered commercial drivers, 327were selected using multistage sampling methods. Structured questionnaire was administered by trained research assistants. PSRT test and visual function tests were carried out by the principal researcher and an assistant. Subject with normal healthy macular function should be able to read the visual acuity line just above the pre-exposure visual acuity line in 50-60 seconds. Patients with a macular problem may have recovery times lasting 1.5 to 3 min or longer. The study revealed a statistically significant association between PSRT and visual acuity as well as colour vision (p<0.05). No association existed between PSRT and age, visual field and driving safety. Majority of the respondents with normal PSRT had fair driving safety. Regular visual screening especially during license renewals may be the most useful tool for the detection of impaired visual function and delayed photo stress recovery time among commercial drivers. Keywords: Photostress, Macular degeneration, Commercial drivers

Multimodal Characterization of Proliferative Diabetic Retinopathy Reveals Alterations in Outer Retinal Function and Structure

To identify changes in retinal function and structure in persons with proliferative diabetic retinopathy (PDR), including the effects of panretinal photocoagulation (PRP). Cross-sectional study. Thirty adults who underwent PRP for PDR, 15 adults with untreated PDR, and 15 age-matched controls. Contrast sensitivity, frequency doubling perimetry (FDP), Humphrey visual fields, photostress recovery, and dark adaptation were assessed. Fundus photography and macular spectral-domain optical coherence tomography (SD OCT) were performed. To quantify retinal layer thicknesses, SD OCT scans were segmented semiautomatically. Visual function measures were compared among patients with PDR and PRP, untreated patients with PDR, and controls. Mean retinal layer thicknesses were compared between groups. Correlation analyses were performed to evaluate associations between visual function measures and retinal layer thicknesses. A significant reduction of FDP mean deviation (MD) was exhibited in PRP-treated patients with PDR (MD ± standard deviation, -8.20±5.76 dB; P < 0.0001) and untreated patients (-5.48±4.48 dB; P < 0.0001) relative to controls (1.07±2.50 dB). Reduced log contrast sensitivity compared with controls (1.80±0.14) also was observed in both PRP-treated patients (1.42±0.17; P < 0.0001) and untreated patients (1.56±0.20; P = 0.001) with PDR. Compared with controls, patients treated with PRP demonstrated increased photostress recovery time (151.02±104.43 vs. 70.64±47.14 seconds; P = 0.001) and dark adaptation speed (12.80±5.15 vs. 9.74±2.56 minutes; P = 0.022). Patients who underwent PRP had diffusely thickened nerve fiber layers (P = 0.024) and diffusely thinned retinal pigment epithelium (RPE) layers (P = 0.009) versus controls. Untreated patients with PDR also had diffusely thinned RPE layers (P = 0.031) compared with controls. Patients with untreated PDR exhibited inner retinal dysfunction, as evidenced by reduced contrast sensitivity and FDP performance, accompanied by alterations in inner and outer retinal structure. Patients who underwent PRP had more profound changes in outer retinal structure and function. Distinguishing the effects of PDR and PRP may guide the development of restorative vision therapies for patients with advanced diabetic retinopathy.

Attenuating Photostress and Glare Disability in Pseudophakic Patients through the Addition of a Short-Wave Absorbing Filter.

To evaluate the effects of filtering short wavelength light on visual performance under intense light conditions among pseudophakic patients previously implanted with a clear intraocular lens (IOL). This was a patient-masked, randomized crossover study conducted at 6 clinical sites in the United States between September 2013 and January 2014. One hundred fifty-four bilaterally pseudophakic patients were recruited. Photostress recovery time and glare disability thresholds were measured with clip-on blue-light-filtering and placebo (clear; no blue-light filtration) glasses worn over patients' habitual correction. Photostress recovery time was quantified as the time necessary to regain sight of a grating target after intense light exposure. Glare disability threshold was assessed as the intensity of a white-light annulus necessary to obscure a central target. The order of filter used and test eye were randomized across patients. Photostress recovery time and glare disability thresholds were significantly improved (both P < 0.0001) when patients used blue-light-filtering glasses compared with clear, nonfiltering glasses. Compared with a nonfiltering placebo, adding a clip-on blue-absorbing filter to the glasses of pseudophakic patients implanted with clear IOLs significantly increased their ability to cope with glare and to recover normal viewing after an intensive photostress. This result implies that IOL designs with blue-light-filtering characteristics may be beneficial under intense light conditions.