Contrast Glare Research Articles

Clinical Study of Customized Selected Aspherical Intraocular Lens Implants

Aims: To compare if there is an improvement in visual functions with age-related cataracts between patients receiving customized selected aspherical intraocular lens (IOL) implants and patients randomly assigned lenses. Methods: Ninety-four patients (94 eyes) with age-related cataracts were placed in experimental group or a group receiving randomly assigned (RA) lenses. All patients were undergone Pentacam corneal spherical aberration measurement before surgery; The targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm in experimental group. Patients with a corneal spherical aberration ≤ 0.3 μm were implanted with a zero-spherical aberration advanced optics (AO) aspherical intraocular lens and patients with an aberration 0.3 μm received a Tecnis ZA9003 aspherical lens. RA patients were randomly implanted with an AO lens or a Tecnis ZA9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and LogMAR vision were measured. Results: Statistical analysis on LogMAR vision showed no significant difference between two groups (P = 0.308). The post-surgical total spherical aberration was 0.120 ± 0.097 μm and 0.158 ± 0.152 μm in the experimental and RA groups, respectively (P = 0.08). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P = 0.00; P = 0.04; P = 0.01). The mesopic with glare contrast sensitivity in the RA group at a spatial frequency of 18 c/d was also significantly higher vs. the RA group (P = 0.02). Conclusion: Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical intraocular lens implants improved mesopic contrast sensitivities and mesopic with glare contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical intraocular lens implants.

Prospective, Randomized, Double-blind, Contralateral Eye Comparison of Myopic LASIK With Optimized Aspheric or Prolate Ablations

To compare the postoperative outcomes of aspheric or prolate LASIK for myopia and myopic astigmatism. In this double-blind, bilateral, randomized trial, 40 patients (80 eyes) with -0.75 to -7.00 diopters (D) of manifest refraction spherical equivalent (MRSE) underwent optimized aspheric treatment zone ablation (OATz group) in 1 eye and optimized prolate ablation (OPA group) in the fellow eye. Six-month postoperative outcomes were compared for MRSE and visual acuity, contrast sensitivity, patient satisfaction, ocular higher order aberrations (HOAs), and spherical aberration. The Wilcoxon signed rank test, Mann-Whitney U test, and paired t test were used for testing differences between groups. P<.05 was statistically significant. Main outcome measures included HOAs, spherical aberration, visual and refractive outcomes, and contrast sensitivity. Postoperatively, 36 patients (72 eyes) were evaluated. The MRSE was -0.07±0.23 D for the OPA group and +0.02±0.24 D for the OATz group (P>.05). Two (5%) eyes in the OPA group and 1 (3%) eye in the OATz group (P=.114) lost 1 line of corrected distance visual acuity. Postoperative visual acuity was not statistically different between groups (P>.05). Statistically lower change was noted in spherical aberration (0.011 μm) in the OPA group versus the OATz group (0.099 μm) (P<.001). Statistically higher induction of coma was noted in the OPA group (P=.035). No statistically significant differences were noted in photopic, mesopic, or glare contrast sensitivity and patient satisfaction between groups (P>.05, for all comparisons). The refractive and visual outcomes of OPA and OATz were equivalent. However, the postoperative optical quality of OPA-treated eyes was better.

Long-term effect of LASEK for the treatment of low to moderate myopia with thin cornea

Objective To evaluate the long term effect and safety of laser subepithelial keratomileusis( LASEK)for the treatment of low to moderate myopia with thin cornea( central corneal thickness ＜ 500 μm) Methods To analyze patients with low to moderate myopia in 5 -7 years after LASEK,and compare the refraction,visual acuity,contrast sensitivity,glare contrast sensitivity,corneal endothelium and corneal topography between pateints with thin cornea and normal thickness cornea.Results Thin cornea group had 27 cases (52 eyes).Normal thickness cornea group had 31 cases (62 eyes).No keratoconus had been observed during the follow-up period in the two groups.The corrected visual acuity of both groups were ≥1.0 ;In the thin cornea group,49 eyes' uncorrected visued acuity were ≥ 1.0,and 3 eyes were ＜ 1.0.In the normal cornea group,58 eyes' uncorreeted visued acuity were ≥ 1.0,and 4 eyes were ＜ 1.0 (x2 ＝ 0.0228,P ＞ 0.05).In the thin cornea group,49 eyes had 0 degree of cornea Haze,and 3 eyes had 0.5 degrees of cornea Haze.On the other hand,in the normal thickness cornea group,60 eyes had 0 degree of cornea Haze,and 2 eyes had 0.5 degrees of cornea Haze(x2 =0.4416,P ＞ 0.05 ).The shapes of the corneal endothelium of bothgroups were quite consistent and appear to be hexagonal,and the cell edge was neat.The average endothelial cell density:(2330±294)/mm2 in the thin cornea group,and (2413 ±320)/mm2 in the normal corneal thickness group; The average endothelial cell area:(420 ± 78 )μm2 in the thin cornea group,and (447 ± 92 ) μm2 ( t =1.6875,P ＞ 0.05 ) in the normal thickness cornea group.The contrast sensitivity of two groups with or without glare condition had significant difference for every spatial frequencies (P ＞ 0.05 ).Conclusion LASEK for the treatment of low to moderate myopia with thin cornea is tested to be safe,stable and with no keratoconus. Key words: Laser subepithelial keratomileusis; Corneal thickness; Keratoconus

Erfahrungen mit der Untersuchung des Kontrastsehens

Since July 2011 driving licensing in Germany requires contrast vision to be tested. Recommendations are available for testing under mesopic conditions only. This study is aimed to provide recommendations for photopic testing. 169 persons were tested both under mesopic (Mesotest) and photopic (Optovist) conditions. With the Mesotest the setting without glare and the requirement to recognize contrast 1:5 or with glare contrast 1:23 proved to be suitable. With the Optovist visual acuity size 0.4 without and 0.25 with glare proved to be adequate, if the requirement is to recognize the limit of 5%. Not unexpectedly, there is no perfect congruence between the tests. We therefore recommend that the screening methods used in industrial medicine need to be sufficiently sensitive and specific, unfortunately this is met only by some of the conditions supplied with the instruments.

Contrast sensitivity evaluation with filter contact lenses in patients with retinitis pigmentosa: a pilot study

Purpose The aim of this pilot study was to test whether retinitis pigmentosa patients would benefit from filter contact lenses as an effective optical aid against glare and photophobia. Methods Fifteen subjects with retinitis pigmentosa were enrolled in this study. All of them were evaluated with filter soft contact lenses (MaxSight), filter glasses (CPF 527) and without filters (control). All patients were assessed for the three aid conditions by means of best corrected visual acuity (BCVA), contrast sensitivity (without glare and with central and peripheral glare)(CSV-1000) and a specific subjective questionnaire about quality of vision. Results BCVA was slightly better with filters than without filter but the differences were not statistically significant. Contrast sensitivity without glare improved significantly with the contact lenses (p < 0.05). The central glare had significant differences for the frequencies of 3 cpd and 18 cpd between the contact lens filter and the control group (p = 0.021 and p = 0.044, respectively). For the peripheral glare contrast sensitivity improved with contact lens versus control group for highest frequencies, 12 and 18 cpd (p < 0.001 and p = 0.045, respectively). According to the questionnaire the contact lens filter gave them more visual comfort than the glasses filter under the scenarios of indoors glare, outdoors activities and indoors comfort. Conclusion The filter contact lenses seem to be a good option to improve the quality of vision of patients with retinitis pigmentosa.

Macular Pigment and Visual Performance in Glare: Benefits for Photostress Recovery, Disability Glare, and Visual Discomfort

One theory of macular pigment's (MP) presence in the fovea is to improve visual performance in glare. This study sought to determine the effect of MP level on three aspects of visual performance in glare: photostress recovery, disability glare, and visual discomfort. Twenty-six subjects participated in the study. Spatial profiles of MP optical density were assessed with heterochromatic flicker photometry. Glare was delivered via high-bright-white LEDs. For the disability glare and photostress recovery portions of the experiment, the visual task consisted of correct identification of a 1° Gabor patch's orientation. Visual discomfort during the glare presentation was assessed with a visual discomfort rating scale. Pupil diameter was monitored with an infrared (IR) camera. MP level correlated significantly with all the outcome measures. Higher MP optical densities (MPODs) resulted in faster photostress recovery times (average P < 0.003), lower disability glare contrast thresholds (average P < 0.004), and lower visual discomfort (P = 0.002). Smaller pupil diameter during glare presentation significantly correlated with higher visual discomfort ratings (P = 0.037). MP correlates with three aspects of visual performance in glare. Unlike previous studies of MP and glare, the present study used free-viewing conditions, in which effects of iris pigmentation and pupil size could be accounted for. The effects described, therefore, can be extended more confidently to real-world, practical visual performance benefits. Greater iris constriction resulted (paradoxically) in greater visual discomfort. This finding may be attributable to the neurobiologic mechanism that mediates the pain elicited by light.

Intraindividual Comparison of Color Perception and Contrast Sensitivity with and without a Blue Light-Filtering Intraocular Lens

To investigate color perception and contrast sensitivity with and without additional glare in pseudophakic patients with a conventional intraocular lens (IOL) in one eye and a blue light-filtering IOL in the fellow eye. Twenty-three bilaterally pseudophakic patients with a conventional IOL (AcrySof SA60AT) and a blue light-filtering IOL (AcrySof Natural SN60AT) were tested for intraindividual comparison of visual acuity (ETDRS chart), color perception (Farnsworth-Munsell 100-Hue test), and contrast sensitivity with and without glare (Contrast Sensitivity Pattern Generator). Information about subjective perception was gathered through a questionnaire. Four patients (17.4%) observed some difference in monocular color perception. Color testing did not show significantly different results for the two IOL types expressed as total error score and segmental error subscores for protan, deutan, and tritan ranges. Regarding contrast sensitivity, 5 patients (21.7%) indicated noticeable difference between the two eyes. Contrast sensitivity testing, however, showed similar curves for the two IOL types with and without additional glare. Despite some subjective difference in color and contrast perception in a minority of patients, the study did not show significantly different results for the two IOL types.

Takagi Glare Tester CGT-1000 for Contrast Sensitivity and Glare Testing in Normal Individuals and Cataract Patients

To investigate the sensitivity and repeatability of the Takagi Contrast Glare Tester CGT-1000 in normal individuals and those with cataracts. A prospective observational study was performed. The Takagi Contrast Glare Tester measures contrast sensitivity (CS) at 6 target sizes and 13 contrast levels (2.00 to 0.34 logCS). Testing follows a method of descending limits paradigm with a single reversal determining threshold. The CGT-1000 was administered with and without glare in 95 eyes of 61 cataract patients and 13 controls. The percentage floor (unable to see the highest contrast) and ceiling (able to see the lowest contrast) effects and correlations between CS and cataract grades were determined. The repeatability was evaluated using Bland-Altman limits of agreement and expressed as the coefficient of repeatability (COR). Factor analysis was used to test for redundancy within the 6 spatial frequencies. In normal individuals, a high rate of ceiling effect varying with target size was noted--for 6.3 degrees, 4.0 degrees, 2.5 degrees, 1.6 degrees, 1.0 degrees, 0.7 degrees, ceiling effects were 68%, 58%, 18%, 11%, 4%, 2%, respectively, for no glare, and 47%, 42%, 8%, 2%, 2%, 2%, respectively, with glare. In cataract patients, floor effects were noted--3%, 0%, 3%, 7%, 19%, 62%, respectively, for no glare, and 3%, 3%, 6%, 14%, 44%, 79%, respectively, with glare. Correlations with cataract grades ranged from 0.10 to 0.61, being best for nuclear cataract. Repeatabilities expressed as COR were +/- 0.11, +/- 0.14, +/- 0.28, +/- 0.38, +/- 0.38, +/- 0.47 logCS, respectively. All spatial frequencies loaded heavily on one factor, indicating no gain in information from testing multiple target sizes. Sensitivity to the presence of cataract was good, but ceiling effects in normal individuals and floor effects in cataract patients limit accuracy. Repeatability was poor, but could be improved by testing less spatial frequencies more rigorously.

Wavefront-guided LASIK for Myopia Using the LADAR CustomCornea and the VISX CustomVue

To evaluate the objective and subjective visual outcomes and refractive results of wavefront-guided LASIK with LADAR CustomCornea and VISX CustomVue. This prospective randomized single-institution multisurgeon study comprised 100 eyes of 58 patients (50 eyes on each laser platform). Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and manifest refraction were measured postoperatively at 1 day, 1 week, 1 month, and 3 months. Contrast sensitivity, higher order aberrations measurement, and a subjective vision questionnaire were performed preoperatively and at 3 months. Preoperatively, the CustomCornea group had a mean manifest sphere of -3.58 +/- 1.61 diopters (D) (range: -0.50 to -7.25 D), cylinder of +0.64 +/- 0.45 D (range: 0 to +1.75 D), and manifest refractive spherical equivalent (MRSE) of -3.26 +/- 1.56 D. The CustomVue group had a manifest sphere of -4.00 +/- 1.69 D (range: -1.50 to -7.50 D), cylinder of +0.60 +/- 0.52 D (range: 0 to +2.00 D), and MRSE of -3.70 +/- 1.64 D. At 3 months, 94% of CustomCornea eyes and 84% of CustomVue eyes had UCVA > or = 20/20 (P = .20). Twenty-four percent of CustomVue eyes and 22% of CustomCornea eyes gained 1 line of BSCVA. In both groups, 96% of eyes were within 0.50 D of emmetropia. Mean CustomCornea glare contrast sensitivity improved (P = .04) whereas more eyes improved than worsened in both groups. Spherical aberration and total higher order aberrations increased, and trefoil decreased in both groups. A decrease in coma was noted in 70% of CustomCornea eyes. Wavefront-guided LASIK with both platforms is safe, effective, and delivers excellent visual results. CustomCornea improves contrast sensitivity under glare conditions.

Early clinical evaluation of visual function in patients with age-related cataract

To investigate the characteristics of visual acuity, contrast sensitivity and glare contrast sensitivity in age-related cataract patients. In this study, 115 eyes of 66 age-related cataract patients with a best corrected visual acuity of 0.5 or better, who had been classified into cortical cataract group (50 eyes of 31 subjects), nuclear sclerosis group (32 eyes of 17 subjects), posterior subcapsular cataract group (33 eyes of 18 subjects); and control group (34 eyes of 34 subjects) were examined with a contrast glare tester to assess contrast sensitivity and glare contrast sensitivity. There were statistically significant differences among contrast sensitivity and glare contrast sensitivity in the cataract patients with different visual acuity at low, medium spatial frequency (P < 0.01); there were no statistically significant differences among those at high spatial frequency (P > 0.05). Cortical cataract was associated with the contrast sensitivity at low, medium spatial frequency, where the glare contrast sensitivity fell into at low, medium and high spatial frequency; in the patients with cataract of nuclear sclerosis was associated with the contrast sensitivity at low spatial frequency, where the glare contrast sensitivity was at low, medium and high spatial frequency; in contrast to posterior subcapsular cataract both the contrast sensitivity and glare contrast sensitivity (at low, medium, high spatial frequency) were lower than normal eyes (P < 0.05). Each spatial frequency of contrast sensitivity and glare contrast sensitivity in 57 cataract eyes with a best corrected visual acuity of 0.8 or better were lower than normal eyes. In those eyes the contrast sensitivity at low spatial frequency and glare contrast sensitivity at low and high spatial frequency had statistically significant difference compared with control (P < 0.05); other spatial frequency had no statistically significant difference among groups (P > 0.05). The glare contrast sensitivity in cataract eyes was lower than contrast sensitivity at visual angle of 6.3 degrees, 4.0 degrees, 2.5 degrees, 1.6 degrees, 1.0 degrees, the difference was statistically significant (P < 0.01). Contrast sensitivity and glare contrast sensitivity are reliable in evaluating visual function in the patients with early age-related cataract.

Easing high brightness and contrast glare problems in universal space design studios in the UAE: Real models testing

The new building of the department of architectural engineering at UAE University introduces a rare form for such a type of function, especially in desert climate. This created an incentive to investigate its performance with regard to daylighting. The study depends mainly on experimental research approach under actual sky using scaled architectural physical models. Based on previous study by the author, it was decided to test two design modifications. These are the adding of external reflective light shelf (in different slopes) to improve the daylighting level and visual comfort in the back space of the first floor studio and the replacement of the current transparent glazing in the existing skylights with a diffusing translucent glazing to improve visual comfort in the third floor studio. Quantitative analysis was conducted based on measurements taken using lighting photometric sensors that were distributed in several locations inside the model. Qualitative analysis was also conducted to assess the visual environment and the presence of glare inside the studio spaces using photography.

Correlation between posterior capsule opacification and visual function before and after Neodymium: YAG laser posterior capsulotomy

Purpose To investigate the correlation between visual acuity, contrast sensitivity, and contrast sensitivity with glare source (glare sensitivity), and the degree of posterior capsule opacification (PCO) before and after neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy. Design Prospective interventional case series. Methods Eighty-four patients (90 pseudophakic eyes) scheduled to undergo Nd:YAG laser capsulotomy were recruited. Visual acuity and contrast sensitivity with and without the presence of a circular glare source (using the contrast glare tester) were measured before and after Nd:YAG laser capsulotomy. The PCO density value was measured using a Scheimpflug videophotography system. The visual functions were statistically correlated with the PCO value. Results Before Nd:YAG laser capsulotomy, strong correlation existed between the PCO value and visual acuity ( r = 0.728). Contrast sensitivity and glare sensitivity were also weakly correlated with the PCO value, but the correlation coefficients were smaller than that of visual acuity. After Nd:YAG laser capsulotomy, mean visual acuity, contrast sensitivity, and glare sensitivity at all visual angles improved significantly ( P <.0001). After capsulotomy, no significant correlation was found between visual acuity, contrast sensitivity, or glare sensitivity and the PCO value. Conclusions Before Nd:YAG laser capsulotomy, visual functions correlated significantly with the degree of PCO. Specifically, visual acuity has a stronger association with PCO than does contrast sensitivity or glare sensitivity and therefore should be considered to reflect most accurately the degree of PCO. After capsulotomy, these visual functions improve markedly and no longer have a significant correlation with PCO.

Visual performance requirements for post‐PRK police recruits

Background: New Zealand Police regulations (1996) allow the unaided visual acuity requirement of 6/12 to be achieved following refractive surgery (except radial keratotomy or keratoplasty) provided applicants also achieve normal (95 per cent confidence limit data from the literature): glare disability, contrast sensitivity, and low luminance visual acuity, one year or more after treatment.Methods: To confirm the limits adopted, 80 young normal adults were subjected to the tests in the regulations. To examine the operation of the current standards, the results of 34 post‐photorefractive keratectomy (post‐PRK) police applicants are reported. Glare disability was the loss of high contrast visual acuity (VA) with the Mentor Brightness Acuity Tester at medium intensity. Contrast sensitivity (CS) was examined using both Melbourne Edge Test thresholds and the VA difference between high and low contrast Bailey‐Lovie charts. Low luminance VA was measured using high contrast Bailey‐Lovie charts viewed through a one per cent transmittance filter.Results: The 95 per cent confidence limits found for normal performance were as follows. Glare disability: no more than 10 letters worse than VA without glare. Contrast sensitivity: no more than 12 letters difference between high contrast and low contrast letter acuity together with an edge contrast threshold of not less than 20 dB (CS = 100). These results were close to the values adopted for the current standard. The 95 per cent confidence limit for low luminance VA was a loss of 24 letters (almost five lines) and not the three lines of loss estimated from the literature. Two of the 34 post‐PRK applicants failed. One was unable to achieve 6/6 acuity with best refraction. The second could not meet the low luminance VA limit (loss no more than three lines). No failures have been due to glare disability or poor contrast sensitivity even though one applicant had obvious corneal haze.

Klinische Ergebnisse nach Implantation einer multifokalen diffraktiven Hinterkammerlinse*

45 diffractive multifocal posterior chamber lenses were implanted in 41 patients. The follow-up time amounted to 12 months. With one correction good visual acuity for far and as well as near distances could be achieved. A significant loss of visual acuity with glare and low contrast and of contrast sensitivity was observed. Future has to show whether the advantages of this multifocal PCL will equal the disadvantages to the modern standard PMMA-PCL.