scholarly journals Greater effect of contrast polarities on visual acuity measurements using chart with shorter wavelength background

2019 ◽  
Vol 14 (4) ◽  
pp. 515-519
Author(s):  
Chen Ai Hong ◽  
Nurulain Muhamad
Keyword(s):  
Visual Acuity ◽  
Repeated Measures ◽  
Negative Polarity ◽  
Blue Colour ◽  
Long Wavelength ◽  
Black And White ◽  
Minimum Angle ◽  
Blue Background ◽  
Human Eyes ◽  
Landolt C

Our study aimed to explore the effect of positive and negative polarities on visual acuity measurements by utilizing black and white as a text against background with three distinct colours. Visual acuity was recorded as logarithm of minimum angle of resolution (LogMAR) using the detection of the gap in a four-position Landolt-C. The 2x3 (polarity x background color) two way repeated measures ANOVA showed a statistically significant interaction between polarity and colour background on visual resolution [F (2, 16) = 23.704, p < 0.001, η2 = 0.744]. Among the three primary background colour, shorter-wavelength (blue background) showed statistically significant findings between both positive and negative polarity [F (1, 9) = 39.875, p < 0.001, η2 = 0.818].  Visual acuity measurements improved with negative polarity but decreased with positive polarity with blue colour background. However, visual acuity was not statistically significantly different with the green (medium-wavelength) [F (1, 11) = 0.625, p = 0.446, η2 = 0.053] and the red (long-wavelength) backgrounds [F (1, 9) = 4.021, p = 0.856, η2 = 0.000]. In conclusion, black text against shorter-wavelength (blue) background apparently more difficult to be resolved by human eyes compared with white text. These findings suggest colour element might be an advantage for negative polarity colour combinations.

Performance Evaluation Tests for Environmental Research (PETER): Landolt C Reading Test

1980 ◽  
Vol 24 (1) ◽  
pp. 335-339 ◽  
Author(s):  
John C. Guignard ◽  
Alvah C. Bittner ◽  
Steven W. Einbender ◽  
Robert S. Kennedy
Keyword(s):  
Visual Acuity ◽  
Performance Evaluation ◽  
Fine Structure ◽  
Repeated Measures ◽  
Performance Test ◽  
Environmental Research ◽  
Future Performance ◽  
Error Measures ◽  
The Stability ◽  
Landolt C

A Landolt C visual acuity test was evaluated for inclusion in a battery of Performance Evaluation Tests for Environmental Research (PETER) for use in repeated measures experiments. Eight subjects were tested for 12 days to determine stability of means, standard deviations and cross-day correlations. Mixed results for these cross-day correlation analyses made questionable the stability of speed and error measures. Fine-structure analyses indicated that the task was more a measure of response accuracy than acuity. Fine-structure analyses in future performance test evaluation and exploration of alternative visual acuity tests are recommended. It is concluded that the Landolt C test in the form used is not stable and cannot be recommended as a test of visual acuity for inclusion in PETER.

scholarly journals Age-related changes of color visual acuity in normal eyes

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0260525
Author(s):  
Sho Yokoyama ◽  
Yoshiki Tanaka ◽  
Takashi Kojima ◽  
Rie Horai ◽  
Yukihito Kato ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Age Groups ◽  
Color Test ◽  
Long Wavelength ◽  
Age Related ◽  
Cone Function ◽  
Minimum Angle ◽  
White Point ◽  
The Difference ◽  
Age Range

Purpose To evaluate the age-related change in color visual acuity (CVA) in normal eyes. Methods In total, 162 normal eyes (162 subjects, women: 52, men: 110, age range: 15–68 years) with best-corrected visual acuity (BCVA) ≥20/13 were enrolled. Fifteen colors from the New Color Test (chroma 6) were applied to Landolt “C” rings, white point D65 was applied as background, and a luminance of 30 cd/m2 was set for both the rings and the background. These rings were used to measure the chromatic spatial discrimination acuity as the CVA value, while changing the stimulus size. Correlations of the CVA value of each color and age were evaluated. Mean CVA values of all 15 colors (logarithm of the minimum angle of resolution) were compared between age groups in 10-year increments. Results Nine CVA values (red, yellow-red, red-yellow, green, blue-green, green-blue, purple, red-purple, and purple-red) were negatively correlated with age (all p<0.05); the remaining six (yellow, green-yellow, yellow-green, blue, purple-blue, and blue-purple), as well as BCVA were not. The age groups with the best to worst mean CVA values of 15 colors were as follows: 20–29 (mean ± standard deviation, 0.303 ± 0.113), 30–39 (0.324 ± 0.096), 10–19 (0.333 ± 0.022), 50–59 (0.335 ± 0.078), 40–49 (0.339 ± 0.096), and 60–69 (0.379 ± 0.125) years. There were statistically significant differences between mean CVA values of the following groups: 20–29 and 40–49 years; 20–29 and 60–69 years; 30–39 and 60–69 years (all p<0.01). Conclusions The CVA values related to the medium/long-wavelength-sensitive cones were more susceptible to aging than those related to the short-wavelength-sensitive cones. This differed from previous reports, and may be related to the difference in the range of foveal cone function evaluated with each examination.

Color stimuli perception in presence of light scattering

2006 ◽  
Vol 23 (3-4) ◽  
pp. 597-601 ◽  
Author(s):  
MARIS OZOLINSH ◽  
MICHÉLE COLOMB ◽  
GATIS IKAUNIEKS ◽  
VARIS KARITANS
Keyword(s):  
Visual Acuity ◽  
Light Scattering ◽  
Luminance Contrast ◽  
White Background ◽  
Color Contrast ◽  
Entire Area ◽  
Red Color ◽  
Blue Component ◽  
Different Color ◽  
Landolt C

Perception of different color contrast stimuli was studied in the presence of light scattering: in a fog chamber in Clermont-Ferrand and in laboratory conditions where light scattering of similar levels was obtained, using different light scattering eye occluders. Blue (shortest wavelength) light is scattered in fog to the greatest extent, causing deterioration of vision quality especially for the monochromatic blue stimuli. However, for the color stimuli presented on a white background, visual acuity in fog for blue Landolt-C optotypes was higher than for red and green optotypes on the white background. The luminance of color Landolt-C optotypes presented on a LCD screen was chosen corresponding to the blue, green, and red color contributions in achromatic white stimuli (computer digital R, G, or B values for chromatic stimuli equal to RGB values in the achromatic white background) that results in the greatest luminance contrast for the white–blue stimuli, thus advancing the visual acuity for the white-blue stimuli. Besides such blue stimuli on the white background are displayed with a uniform, spatially unmodulated distribution of the screen blue phosphor emission over the entire area of the screen including the stimulus C optotype area. It follows that scattering, which has the greatest effect on the blue component of screen luminance, has the least effect on the perception of white–blue stimuli.

scholarly journals Quality of eyeglass prescriptions from a low-cost wavefront autorefractor evaluated in rural India: results of a 708-participant field study

2019 ◽  
Vol 4 (1) ◽  
pp. e000225 ◽  
Author(s):  
Nicholas J Durr ◽  
Shivang R Dave ◽  
Daryl Lim ◽  
Sanil Joseph ◽  
Thulasiraj D Ravilla ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Form Factor ◽  
Low Cost ◽  
Rural India ◽  
Resource Setting ◽  
Low Resource Setting ◽  
Significant Difference ◽  
Minimum Angle ◽  
The Mean

ObjectiveTo assess the quality of eyeglass prescriptions provided by an affordable wavefront autorefractor operated by a minimally trained technician in a low-resource setting.Methods and Analysis708 participants were recruited from consecutive patients registered for routine eye examinations at Aravind Eye Hospital in Madurai, India, or an affiliated rural satellite vision centre. Visual acuity (VA) and patient preference were compared between trial lenses set to two eyeglass prescriptions from (1) a novel wavefront autorefractor and (2) subjective refraction by an experienced refractionist.ResultsThe mean±SD VA was 0.30±0.37, –0.02±0.14 and −0.04±0.11 logarithm of the minimum angle of resolution units before correction, with autorefractor correction and with subjective refraction correction, respectively (all differences p<0.01). Overall, 25% of participants had no preference, 33% preferred eyeglass prescriptions from autorefraction, and 42% preferred eyeglass prescriptions from subjective refraction (p<0.01). Of the 438 patients 40 years old and younger, 96 had no preference and the remainder had no statistically significant difference in preference for subjective refraction prescriptions (51%) versus autorefractor prescriptions (49%) (p=0.52).ConclusionAverage VAs from autorefractor-prescribed eyeglasses were one letter worse than those from subjective refraction. More than half of all participants either had no preference or preferred eyeglasses prescribed by the autorefractor. This marginal difference in quality may warrant autorefractor-based prescriptions, given the portable form factor, short measurement time, low cost and minimal training required to use the autorefractor evaluated here.

Outcomes After the Use of Silicone Oil in Complex Retinal Detachment Repair

2020 ◽  
Vol 4 (2) ◽  
pp. 96-102
Author(s):  
Omar A. Saleh ◽  
Efrat Fleissig ◽  
Charles C. Barr
Keyword(s):  
Visual Acuity ◽  
Retinal Detachment ◽  
Chart Review ◽  
Silicone Oil ◽  
Retrospective Chart Review ◽  
Final Visit ◽  
Complication Rates ◽  
Minimum Angle ◽  
The Mean ◽  
Better Than

Purpose: This study compares visual acuity (VA), anatomic outcomes, and complications in eyes that underwent complex retinal detachment (RD) repair in which silicone oil (SO) was retained vs removed. Methods: A retrospective chart review of patients undergoing vitrectomy with SO tamponade. The eyes were divided into 2 groups based upon SO removal or retention. Main outcome measures were corrected VA, anatomic outcomes, and the presence of SO-related complications. Results: Fifty-seven eyes with removed SO and 53 eyes with retained SO were identified. In both groups, the mean best-corrected VA (BCVA) at the final visit was significantly better than at baseline. In the retained-SO group, vision improved from 1.79 ± 0.6 to 1.2 ± 0.7 logarithm of the minimum angle of resolution (logMAR) (Snellen, 20/1200 to 20/350) at the final visit ( P < .001). In the removed-SO group, mean BCVA improved from 1.84 ± 0.5 at baseline to 1.55 ± 0.6 logMAR units (Snellen, 20/1400 to 20/700) at the visit preceding SO removal ( P < .002) and to 1.43 ± 0.6 logMAR units (Snellen, 20/500) at the final visit ( P < .001). Complication rates were similar in both groups, apart from RD, which occurred more frequently in the removed-SO group ( P = .03). Conclusions: There was similarity in VA and complications among patients with removed or retained SO. Removal of SO may benefit eyes with SO-related complications, but SO retention may decrease the chance of RD and may be indicated in selected cases.

The Accuracy of Drivers' Judgments of the Effects of Headlight Glare on Their Own Visual Acuity

Perception ◽  
10.1068/p7814 ◽  
2014 ◽  
Vol 43 (11) ◽  
pp. 1203-1213 ◽  
Author(s):  
Ashley A Stafford Sewall ◽  
Stephanie A Whetsel Borzendowski ◽  
Richard A Tyrrell
Keyword(s):  
Visual Acuity ◽  
Older Drivers ◽  
Visual Performance ◽  
High Beam ◽  
Disability Glare ◽  
Landolt C

Drivers' judgments of the magnitude of disability glare caused by high-beam headlights may not match actual declines in visual performance. This study investigated younger and older drivers' beliefs about their own visual performance in the presence of headlight glare. Eleven older drivers and seventeen younger drivers judged the distance at which they would just be able to recognize the orientation of a white Landolt C if it were present adjacent to the headlamps of a stationary opposing vehicle at night. The younger participants were generally accurate in their estimates of the recognition distance of the stimulus, while older participants significantly overestimated both their own acuity and the effect of glare on their vision. From this study, we see that older drivers' judgments about the disabling effects of oncoming headlights may be systematically inaccurate. These misperceptions about headlight glare may help explain why drivers tend to underuse high beams.

Visual Acuity at Hyperbaric Air Pressure

1976 ◽  
Vol 43 (3) ◽  
pp. 983-986 ◽  
Author(s):  
N. A. M. Schellart
Keyword(s):  
Visual Acuity ◽  
Pressure Chamber ◽  
Air Pressure ◽  
Considerable Reduction ◽  
Open Sea ◽  
Landolt C

The visual acuity of five divers in a dry pressure chamber was measured with a Landolt C test. Only one of them showed a significant reduction at 7.0 atm. These results contrast sharply with open sea experiments, which show a considerable reduction at much lower pressures (Baddeley, 1968). It is suggested that besides stresses, luminance differences, also turbidity, as a function of depth may account for the discrepancy.

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