Disability Glare Research Articles

Impact of Perioperative Dry Eye Treatment with Rebamipide Versus Artificial Tears on Visual Outcomes After Cataract Surgery in Japanese Population.

IntroductionThe present study aimed to compare the effects of rebamipide and artificial tears during the perioperative period of cataract surgery on the postoperative visual outcomes.MethodsSeventy-two eyes from 36 patients with a cataract were enrolled. Rebamipide (group R) was administered in one eye and Mytear® artificial tear ophthalmic solution (group A) in the other eye from 4 weeks preoperatively to 3 months postoperatively. Tear breakup time (TBUT), high-order aberrations (HOAs), superficial punctate keratopathy in the central part of the cornea (C-SPK), and corrected distance visual acuity (CDVA) were assessed at baseline, 1 week, 1 month, and 3 months after cataract surgery with trifocal intraocular lens (IOL) implantation. Contrast sensitivity and disability glare with visual angle values compatible with spatial frequencies of 1.1, 1.8, 2.9, 4.5, 7.1, and 10.2 cycles/degree (CPD) were evaluated postoperatively. Between-group differences of all variables were analyzed.ResultsAt baseline, no significant differences in the variables were noted between the two groups. Mean TBUT was significantly higher, while mean C-SPK and HOAs were significantly lower in group R than in group A at each assessment. Mean CDVA was significantly higher at 1 week and 1 month postoperatively in group R compared with group A; this value was not significant at 3 months. Between-group differences in contrast sensitivity and disability glare were statistically significant at all spatial frequencies, 1 week and 1 month postoperatively. At 3 months postoperatively, there were significant differences in contrast sensitivity and disability glare at most spatial frequencies.ConclusionDry eye management with rebamipide in the perioperative period of cataract surgery with trifocal IOL implantation was significantly more effective than artificial tears in improving ocular surface condition, contrast sensitivity, and disability glare postoperatively.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40123-022-00523-w.

Reduced Vision-Related Quality of Life in Dementia: A Preliminary Report

Background: Despite experimental evidence for concurrent dementia and visual impairment, there are no currently validated vision-related quality of life measures for use in this population. Objective: To establish the extent to which individuals with mild to moderate dementia self-report visual impairment and determine the efficacy of established vision-related quality of life measures for use in a dementia population. Methods: We compared vision-related quality of life in participants with mild-moderate dementia to healthy (dementia-free) older adults using two existing questionnaire measures already validated for use in older adults. These were the Visual Activities Questionnaire (VAQ) and the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25). Results: Responses on both the VAQ and VFQ-25 revealed a significant effect of dementia on self-reported vision-related quality of life. Visual impairment in dementia was identified in the domains of color discrimination, disability glare, light/dark adaption, acuity/spatial vision, depth perception, peripheral vision, visual search, and visual processing speed. Factor analysis of the data suggested that existing vision-related quality of life measures, designed for use in older adult populations, are likely to provide a robust means of assessing vision-related quality of life in older adults with dementia. This is particularly true of the VAQ, for which one latent factor emerged for both dementia and dementia-free samples. Conclusion: Using existing measures designed for use in older adult populations, we have shown that people with dementia experience reduced vision-related quality of life.

An empirical investigation of disability glare and visibility level during driving inside very long road tunnels: A case study

IntroductionDisability glare from lighting systems is considered to be one of the main causes of accidents in road tunnels. The present study aimed to investigate the estimated method of disability glare, the experimental method of visibility level, overall uniformity, and longitudinal uniformity of the tunnel lighting system during driving inside very long road tunnels. MethodsThe disability glare in different road sections of the tunnel was estimated based on the threshold increment (TI) recommended by the CIE 88–2004 method. For visibility level measurements, a standard 20 × 20 cm barrier with a reflection coefficient of 20% was placed in different road sections of the tunnel, and the barrier visibility level was recorded as a self-reported questionnaire by 40 professional drivers in four age groups. The estimated method was used to compare the disability glare data with the experimental method of visibility level. Also, in order to investigate the effect of overall uniformity and longitudinal uniformity in different road sections of the tunnel on visibility level, according to the IESNA LM-71-96 and IESNA LM-50-99 standards, these factors were also examined. ResultsFor the age groups of 19, 40, 64, and 80 years, respectively, the TI in the north lane in road sections 5 (17.7%, 18.4%, 28.65%, 44.3%), 8 (28%, 31.3%, 41.2%, 52.7%), and in the south lane in road section 4 (16.8%, 17.4%, 24.2%, 41.3%) had a higher disability glare than the CIE88 standard (TI = 15%). The results showed that visibility levels were reduced in sections of roads with higher disability glare. Also, in road sections 5 and 8 of the north lane and road section 4 of the south lane, longitudinal uniformity was equal to 0.53, 0.57, and 0.5, respectively, which is less than the CIE88 recommended (0.6),Therefore, when comparing longitudinal uniformity with visibility level, it showed that visibility decreased significantly in these road sections. However, although overall uniformity was reported to be less than standard in most road sections, no correlation was observed between overall uniformity and visibility level. The estimation method also showed that the level of disability glare in drivers’ increased with age, which was associated with a decreased visibility level in the experimental study. ConclusionThere is an inverse relationship between the theoretical equations of disability glare and the decreasing visibility level in different road sections of the tunnel. A direct relationship was observed between visibility level and longitudinal uniformity. But this relationship between visibility level and overall uniformity was not observed. Also, age had a significant effect on disability glare in different road sections of the tunnel.

Optical instrument for the study of time recovery from total disability glare vision.

Disability glare is defined as the loss of contrast sensitivity of the retinal image due to intraocular straylight originated from the presence of an intense and broad bright light in the field of vision. This loss of vision can range between vision loss at high spatial frequencies or total temporal blindness. If the extreme case occurs, the recovery time is crucial in night driving conditions or those professional activities in which maximum visual acuity is required at any moment. The recovery time depends mainly on the intensity and glare angle of the light source, ocular straylight, and the photoreceptor response at the retina. The recovery time can also be affected by ocular pathologies, aging, or physiological factors that increase ocular straylight. The aim of this work is to develop a new optical instrument based on psychophysical methodology as well as to investigate the recovery time from total disability glare (photobleaching) as a function of the contrast of the visual target and the glare angle of the source in healthy volunteers. Results showed significant exponential correlation between recovery time and contrast of the visual target and linear correlation between contrast sensitivity and the glare angle. Those findings allowed to obtain an empirical expression to compute the recovery time required to restore contrast sensitivity baseline vision after photobleaching. Finally, a statistical dependence of recovery time with age was found for short glare angles that disappear as the glare angle increases.

Study on the Influence of Opposing Glare from Vehicle High-Beam Headlights Based on Drivers’ Visual Requirements

The anti-glare facilities in median strips are designed to block opposing headlights in order to avoid disability glare, but a large amount of headlight leakage results in uncomfortable glare, to the point that drivers can barely detect dangerous obstacles or road conditions. This paper aims to explore the glare range under high-beam headlights on drivers’ visual requirements. Based on an analysis of the mechanism of headlight glare, this paper proposes a subjective headlight glare scale, and classifies glare discomfort into two categories: interference glare, and acceptability glare. Combining the scales, 24 drivers and a standard light-emitting diode automotive headlamp were used to conduct glare effect tests. The size of the laboratory that closes to scotopic vision is 12 m × 6 m. The illuminance thresholds of disability glare–interference glare (DGIG) and interference glare–acceptability glare (IGAG), along with the spatial distribution of each glare level, were collected at the longitudinal distances of 3 m, 5 m, 7 m, 10 m, and 12 m. Meanwhile, the illuminance threshold and the spatial distribution of each glare level up to a longitudinal distance of 120 m were calculated. The results indicate that disability glare is distributed in the central area, while interference glare and acceptability glare are distributed from the center to the margins. At the same longitudinal distance, the vertical illuminance of the driver’s eye under the same glare level is almost equal. In the range of a longitudinal distance of 120 m, the spatial distribution of each glare level enlarges with each increase in longitudinal distance. The results can provide scientific evidence for calculating the reasonable heights of anti-glare facilities for expressways with different alignments.

The Blue Light Hazard Versus Blue Light Hype

The blue light hazard is the experimental finding that blue light is highly toxic to the retina (photic retinopathy), in brief abnormally intense exposures, including sungazing or vitreoretinal endoillumination. This term has been misused commercially to suggest, falsely, that ambient environmental light exposure causes phototoxicity to the retina, leading to age-related macular degeneration (AMD). We analyze clinical, epidemiologic, and biophysical data regarding blue-filtering optical chromophores. Perspective. Analysis and integration of data regarding the blue light hazard and blue-blocking filters in ophthalmology and related disciplines. Large epidemiologic studies show that blue-blocking intraocular lenses (IOLs) do not decrease AMD risk or progression. Blue-filtering lenses cannot reduce disability glare because image and glare illumination are decreased in the same proportion. Blue light essential for optimal rod and retinal ganglion photoreception is decreased by progressive age-related crystalline lens yellowing, pupillary miosis, and rod and retinal ganglion photoreceptor degeneration. Healthful daily environmental blue light exposure decreases in older adults, especially women. Blue light is important in dim environments where inadequate illumination increases risk of falls and associated morbidities. The blue light hazard is misused as a marketing stratagem to alarm people into using spectacles and IOLs that restrict blue light. Blue light loss is permanent for pseudophakes with blue-blocking IOLs. Blue light hazard misrepresentation flourishes despite absence of proof that environmental light exposure or cataract surgery causes AMD or that IOL chromophores provide clinical protection. Blue-filtering chromophores suppress blue light critical for good mental and physical health and for optimal scotopic and mesopic vision.

Evaluation of the association between macular damage and disability glare in patients with advanced glaucoma.

This study aimed to investigate the factors associated with disability glare in patients with advanced glaucoma and evaluate the impact of disability glare on the vision-related quality of life. We prospectively studied 225 eyes (225 patients) with advanced glaucoma. The visual function was evaluated using the 10-2 and 24-2 Humphrey visual field (VF)(Dublin, California) and contrast sensitivity test. Structural parameters were obtained using RTVue optical coherence tomography and angiography(Fremont, California). Significant loss of macular vessel density (mVD) was defined as VD < 30%. Each participant completed the National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25) and questions regarding subjective symptoms of glare. Fifty-six patients (24.9%) experienced glare and had a lower NEI-VFQ-25 composite score (P = 0.017). The average retinal nerve fiber layer and ganglion cell complex thickness and mean deviation (MD) in the 24-2 VF test were not associated with glare. Significant superior or inferior mVD loss (P < 0.001; odds ratio [OR], 3.45; and 95% confidence interval [CI], 1.83-6.55), lower logarithmic contrast sensitivity at 0.75 cycles/degree (P < 0.001; OR, 0.27; and 95% CI, 0.13-0.56), and worse MD in the 10-2 VF test (P < 0.001; OR, 0.93; and 95% CI, 0.89-0.97) showed an association with glare. In advanced glaucoma, central VF defect and mVD loss are associated with disability glare, which negatively impacts vision-related quality of life.

Mesopic Disability Glare in Stage-Two Dysfunctional Lens Syndrome.

IntroductionThere is a lack of evidence about the exact deterioration of visual function associated with the age-related natural changes in the lens, particularly in intermediate (stage-2) dysfunctional lens syndrome (DLS). Standard photopic visual acuity and contrast sensitivity tests may not show the visual worsening in daily life activities, such as oncoming vehicle headlights at night. The purpose of this study was to analyze visual function under different conditions and glare sources in stage-2 DLS.MethodsForty patients over 49 years of age with initial bilateral lens opacification (Lens Opacities Classification System III [LOCS-III] scores up to 3), best-corrected visual acuity of 20/25 or better, and no ocular disease were evaluated. Binocular photopic and mesopic contrast sensitivity (CS) with/without halogen and xenon increasing glare sources were analyzed. Mesopic disability glare (MDG) was calculated as the difference between mesopic CS with/without the glare source.ResultsThe median logarithmic CS (logCS) values were lower under mesopic conditions (1.05) than under photopic illumination (1.65; P < 0.001). Halogen and xenon glare further decreased mesopic CS (both, median logCS 0.75, P < 0.001). The mean MDG was 0.31 ± 0.10 log units for halogen glare and 0.33 ± 0.09 log units for xenon glare. The mesopic CS and MDG were not associated with any photopic test. The mesopic CS with glare but not photopic CS or mesopic CS was correlated with the LOCS-III scores. The best association was provided by MDG, which showed a pooled correlation with LOCS-III nuclear opalescence (r = 0.411, P < 0.001) and cortical scores (r = 0.226, P = 0.04).ConclusionThe mesopic CS under a glare source is an independent early indicator of visual impairment in stage-2 DLS patients, and appears to be substantial. Furthermore, the MDG is more sensitive than photopic and mesopic CS for evaluating patients with initial phacosclerosis. Surgeons should consider this in the decision-making process of the correct timing for lens surgery.

Pupillary response in adults with Marfan syndrome and its effect on straylight.

The main objective of this study was to examine the pupillary response in patients with Marfan syndrome (MFS) and secondarily to determine whether changes in the pupillary response are associated with the increased disability glare previously shown in the same patient population. This study included 60 eyes of 34 patients with MFS diagnosed in accordance with the Ghent-2 criteria and 81 eyes of 44 controls. Pupillary response was measured with a pupillograph and disability glare with a straylight meter. The patients with MFS had a significantly smaller maximum pupil size than the control group, 4.87 (4.50-5.23) mm versus 5.58 (5.25-5.90) mm (p = 0.01). In addition, they exhibited slower contraction velocities (p = 0.03) and longer re-dilation times (p = 0.01) compared with the control group. The mean straylight value was higher in patients with MFS than controls, even when including pupillary parameters together with lens surgery, cataract, iris colour, axial length and corneal curvature as possible explanatory variables in the analysis. However, when including data from both groups, a significant negative correlation was seen between maximum pupillary diameter and straylight value (p = 0.01). The other pupillary parameters did not correlate with straylight. Patients with MFS had a smaller maximum pupil diameter, slower pupillary contraction and longer re-dilation time than the controls. Despite the correlation between pupil size and straylight value, the pupillary response demonstrated in MFS eyes could not explain the increased straylight in these patients.

The Effect Of Display Brightness On Visual Function For Young And Old Drivers

Nowadays outdoor advertising displays have become popular. Bright displays near the roads could cause drivers to experience disability or discomfort glare, especially at night. Disability glare increases with age, but discomfort glare thresholds are independent of age. The aim of the study was to assess a luminance level of displays, which causes glare for younger and older subjects. 24 young subjects age of 20 to 24 years and 13 older subjects age of 55 to 69 years participated in the study. The task was by using the method of adjustment to find out the acceptable level of display brightness when the recognition of high (>90%) contrast objects was comfortable. Measurements were done in a photopic and mesopic lighting conditions. Results showed that discomfort glare were larger in mesopic than in photopic lighting conditions (p < 0.001) for both age groups. Preferred display brightness in both lighting conditions did not significantly differ between age groups (p > 0.05). We can conclude that discomfort glare thresholds for displays with textual elements are independent of age.

Glare and Mobility Performance in Glaucoma: A Pilot Study.

Glare disability affects patients with moderate and severe glaucoma. Under glare conditions, mobility performances of glaucoma patients are reduced. The aim of this study was to evaluate glare disability and its impact on mobility and orientation in glaucoma patients. Twenty-two glaucoma patients and 12 age-matched control subjects were included. All patients underwent a clinical evaluation of visual function and halo size measurements to determine glare disability with a glare score (GS) of the best eye and worse eye. Mobility was evaluated by 4 mobility courses on an artificial street (StreetLab) under photopic conditions (P) and mesopic conditions with an additional light source in front of the patient to mimic dazzling conditions (M+G). Mobility time, mobility incidents, trajectory segmentation, distance traveled, preferred walking speed on trial (WS) and percentage of preferred walking speed (PPWS) were recorded, and the Nasa task load index (Nasa-TLX) was evaluated. GS of the worse eye and GS of the best eye were significantly higher in glaucoma patients than in the control group (P=0.001 and 0.003). It was significantly different between moderate glaucoma patients and controls (P=0.001 and 0.010, respectively) and between severe glaucoma patients and controls (P=0.049 and 0.016). In locomotion tasks, comparing performance under M+G and P conditions, mobility performance was significantly different concerning mobility time (P=0.010), distance traveled (P=0.008), WS (P=0.007), PPWS (P=0.006), and Nasa-TLX (P=0.017) in the glaucoma group. Under M+G lighting conditions, mobility performance for glaucoma patients was significantly worse than controls with regard to WS (P=0.038), PPWS (P=0.0498), mobility time (P=0.046), and Nasa-TLX (P=0.006). Glare disability was observed in patients with moderate and severe glaucoma and had an impact on their mobility performance.

Visual outcome and optical quality of a wavefront-engineered extended depth-of-focus intraocular lens.

To evaluate visual performance and optical quality of an extended depth-of-focus intraocular lens (EDoF IOL) compared with a monofocal aspheric IOL. Department of Ophthalmology, Charité-Medical University Berlin, Germany. Prospective case series. After phacoemulsification, a total of 28 patients (56 eyes) underwent bilateral implantation of either the Mini Well (EDoF IOL) or the Mini 4 (monofocal IOL). Assessments including refraction, distance, intermediate and near visual acuity, defocus curves, contrast sensitivity, glare disability, higher-order aberrations (HOAs), and patient satisfaction were performed at 1 month and 3 months postoperatively. Both study groups comprised 14 patients (28 eyes) each. At 3-month follow-up, the EDoF IOL showed better results in monocular uncorrected intermediate visual acuity (-0.04 vs 0.10 logMAR, P = .000) and in uncorrected near visual acuity (0.13 vs 0.36 logMAR, P = .000), whereas no statistically significant difference was found between groups in monocular uncorrected distance visual acuity (0.04 vs 0.00 logMAR, P = .110). The monocular depth of focus was 0.8 D greater in the Mini Well IOL group. Measurements of internal HOAs revealed a greater negative primary spherical aberration in the EDoF group at pupil sizes of 2.0 to 5.0 mm. At 5.0 mm, total internal HOAs did not differ statistically significantly (0.376 vs 0.340 μm root mean square, P = .068). The Mini Well IOL provided greater depth of focus with superior outcomes at intermediate and near distances and comparable outcomes at far distance. Although inducing higher amounts of spherical aberration, it showed good results under low lighting conditions with little subjective dysphotopsia.

Photophobia and disability glare in adult patients with Marfan syndrome: a case-control study.

The aim of the present study was to investigate photophobia and disability glare in adult patients with Marfan syndrome (MFS). In this case-control study, 44 patients with MFS (87 eyes) were compared to 44 controls (88 eyes), who were matched for age and sex. The subjects were asked to grade their photophobia and glare using 10-cm visual analogue scales (VAS), which were marked with 'never' at zero and 'always' at 10 -cm. In addition, disability glare was measured with C-Quant straylight meter. The patients with MFS had significantly higher VAS scores than the controls in four out of seven statements related to photophobia and glare. When including cataract, spherical equivalent, iris colour, axial length and corneal curvature, three of the seven statements were still significantly different between the two groups. The mean straylight values were 1.29 ± 0.03 log(s) in the MFS group and 1.01 ± 0.03 log(s) in the control group (p < 0.001, mixed model). These differences remained significant after adjusting for cataract, spherical equivalent, iris colour, axial length and corneal curvature. Patients with MFS reported more photophobia and had a higher straylight value than the control group. Awareness of these findings of more photophobia and glare in the MFS patients is important when counselling and treating these patients.

Binocular Visual Field and Vision-Related Quality of Life in Patients With Hemianopia.

Hemianopias can have a severe impact on functional ability and quality of life (QoL). Binocular visual field (VF) analysis is clinically more relevant to visual function than monocular VF. The aim is to analyze the binocular VF of patients with hemianopias and its association with the monocular VF and to assess the QoL of these patients through questionnaires specifically related to vision compared with healthy controls. The case-control study included patients with hemianopias and controls. Sex, age, general history, etiology, location of the lesion, and time since the lesion appeared were recorded. Monocular VF and Esterman binocular VF were performed. VF defect, mean defect (MD), and Esterman scores were recorded. Visual Activities Questionnaire (VAQ-33) and Visual Function Questionnaire (VFQ-25) questionnaires were administered. Twenty patients with hemianopia and 22 healthy controls were included. The Esterman score in homonymous hemianopia patients (n = 17) correlated with best eye MD (r = -0.62, P = 0.01), worst eye MD (r = -0.70, P = 0.002), and average MD (r = -0.68, P = 0.003). Compared with healthy control subjects, patients with homonymous hemianopia had significantly lower VFQ-25 score and in 10/12 subscales (all P < 0.001). VAQ-33 scores revealed lower overall and subscales scores with the exception of light/dark adaptation (P = 0.08). Correlations were found between monocular and binocular VF scores and general vision (r = -0.55), peripheral vision (on both questionnaires, r-range -0.75 to 0.47), VFQ-25 and VAQ-33 overall scores (r = -0.59, -0.49 and 0.50), and glare disability (r = 0.53 and 0.67). Hemianopic VF defects involve a major alteration in the patients' vision-related QoL.

The effect of veiling luminance on the disability glare of car headlamps designed in Iran

ABSTRACT Objectives. One of the main risk factors involved in increasing driving accidents at night is due to the veiling luminance of the car’s headlights reducing the contrast of images in the retina and, thus, reducing the visual performance of drivers. The aim of this study is to investigate the veiling luminance caused by the headlights of the best-selling vehicles in Iran. Methods. Using the Stiles–Holiday disability glare equation, the veiling luminance of headlights of common vehicles at distances of 10–100 m for both high-beam and low-beam modes of oncoming vehicles was measured on a road for healthy (young, middle-aged and older) drivers. Results. Under high-beam illumination, as the cars approached each other, the average illuminance of the car headlights gradually increased. Moreover, age had a significant impact on the veiling luminance. This study also showed that, in same-age groups, the Samand Souren and Peugeot Pars cars had the highest and lowest mean veiling luminance, respectively. Conclusion. The findings showed that the illuminance (at large distances between two cars) and the angle between the source of glare and the eyes of drivers (as two cars approach to each other) have a dominant influence on the disability glare.

Night-time disability glare of constant-light LED traffic monitoring fill light

Fill light, used to helps cameras capture road traffic conditions at night, can lead to serious visual consequences for drivers. Research on disability glare from LED fill light is scarce and therefore this study explored strategies for controlling disability glare of constant-light LED traffic monitoring fill light. The threshold increment was used as an index to evaluate disability glare. The effective disability glare area of LED traffic monitoring fill light was determined based on high dynamic range technology. According to visual efficacy theory, there is a relationship between disability glare conditions and reaction times. The influencing factors include background luminance, luminance contrast and fill light luminance. The results showed that disability glare was the most intense in a range of 20 m to 30 m in front of LED fill light. To reduce the effect of disability glare on drivers, luminance contrast between small targets and the road surface should be greater than 0.5. The fill light luminance should not be greater than 100,000 cd/m2.

Disability glare and nighttime driving performance among commercial drivers in Ghana.

ObjectiveGlare caused by the headlights of on‐coming vehicles risk safe driving at night. The study aimed to determine the relationship between glare exposure and nighttime driving performance among commercial drivers in Ghana.MethodsThis cross‐sectional study involved commercial drivers with complaints of nighttime driving difficulties (N = 80; mean age = 41.5 ± 11.1 years). A questionnaire was used to investigate nighttime driving performance following glare exposure. We measured contrast sensitivity and visual acuity under photopic conditions. With an experimental setup in a mesopic setting, we measured visual acuity with and without glare exposure. The difference between the two mesopic visual acuities was quantified as disability glare index. With the same setup, photostress recovery time was also measured. Regression analyses were used to determine the relationship between nighttime driving performance score and the measures taken in both photopic and mesopic settings.ResultsThe average nighttime driving performance score was 47.8 ± 17.5. Driving performance was negatively correlated with all variables (R = –0.87 to –0.30, all p < .01), except contrast sensitivity (R = 0.74, p < .01). A multiple linear regression showed that the model with all variables explained 83.8% of the variance, but only disability glare index was a significant predictor of nighttime driving performance following glare exposure (standardized B = –0.61, p < .01).ConclusionOur results show that the change in mesopic visual acuities following glare can predict nighttime driving performance. This measure can be incorporated into the assessment of driving fitness by licensing departments to evaluate whether a person can drive safely at night amidst glare exposure.

Evaluation of disability glare caused by headlights of most common vehicles in Iran

Background and Objectives: Road traffic accident is one of the leading causes of death in some countries such as Iran. Disability glare due to headlights of vehicles can increase the risk of crashes and make dangerous conditions. This study aimed to investigate the level of glare induced by the headlights of most common vehicles in Iran. Materials and Methods: This cross-sectional study was conducted in a suburban road of Ilam province in 2019. The disability glare resulted from the headlights of Pride Saba GTX, Pride 131SL, Samand Soren, Peugeot 405, Megan, and Peugeot Pars was measured at the distances of 10–100 m away from the headlights. The Threshold Elevation index under the high-beam and low-beam conditions (headlight's operation modes) was obtained for the background luminance condition including 1 and 50 cd/m2 for the age groups of 20, 35, 70, and 83 years old. Results: When the background luminance was 1 cd/m2, the mean glare level caused by the high-beam mode of illumination exceeded the recommended disability glare thresholds of all age groups. When the background luminance was 50 cd/m2, at certain longitudinal distances, glare level exceeded the disability glare thresholds of the elderly drivers (aged 70 and 83 years). At the background luminance of 1 cd/m2, low-beam mode of illumination caused disability glare at certain distances but not in general. At the background luminance of 50 cd/m2, low-beam mode of illumination did not cause disability glare at any distance. Conclusion: The results showed the mutual effect of luminance and the angle of line of sight with respect to glare source on the emergence of disability glare. The age also exhibited a significant association with the disability glare, as the highest glare levels were obtained for older drivers.

The Effect of Night Glare on Myopia

Purpose : This study is to investigate the effect of night glare on myopia.Methods : Forty eight myopic eyes aged 20 to 30 year old were under the indoor illumination 1 lx or less for 5 minutes for the mesopic adaptation. Subjects were grouped by the equivalent spherical refraction -3.25 D. The group 1 with the refraction under -3.25 D and the group 2 with over -3.25 D were compared and analyzed. Two 100 Watt bulbs were placed by the side of the target whose illuminance at the position of subject's pupil was measured. The disability glare (contrast visual acuity and contrast sensitivity) was measured at 2, 5, and 10 lx and the discomfort glare was quantified by Deboer glare scale. The contrast acuity was measured by Reverse- Contrast chart at 100%, 25% and 10% of contrast LogMAR chart and the contrast sensitivity using the iPad program Clinic CSF 2.0 was measured at 3, 6, 12 and 18 cycles per degree.Results : The contrast acuity and contrast sensitivity of disability glare were both high in the group 1. The contrast acuity showed a significant difference after glare occurred (p 0.05).Conclusion : Considering the trend of higher nighttime activity in Korea, it is thought that not only a standard vision test for the night and the prescription to intervene the glare is needed regardless of age.

Reduced Contrast Sensitivity Function in Central and Peripheral Vision by Disability Glare.

Various glares can decrease visual performance and cause discomfort, thus increasing drivers' risk for traffic accidents in real life. The current study aimed to systematically investigate glare sensitivity in the central and peripheral visual fields by measuring contrast sensitivity function (CSF) under nonglare, steady glare, and transient glare conditions. Nine observers with normal visual acuity in the dominant eye were enrolled. The CSF in central and peripheral vision (the 5° upper left visual field) was measured in a mesopic environment while the stimulus was displayed under three conditions: nonglare, steady glare, and transient glare. An orientation identification task was used to obtain the CSF. After the experiment, the observers were asked to report their level of discomfort in the presence of the glare. The area under the log CSF (AULCSF) and cut-off spatial frequency served as indicators of visual performance. In agreement with previous studies, both steady and transient glare reduced the AULCSF and cut-off frequency. However, the AULCSF and cut-off frequency were reduced more for central vision than for nearly peripheral vision. In addition, the extent of the decreases in the AULCSF and cut-off frequency was greater for steady glare than for transient glare; in contrast, more discomfort was associated with transient glare than steady glare.