Visual Acuity with Astigmatic Blur

Atchison, David A.; Mathur, Ankit

doi:10.1097/opx.0b013e3182186bc4

Cited by 48 publications

(56 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similar results were found by Atchison et al 37 and Applegate et al 38 However, for small levels of crossed cylinder blur (≤0.75 DC), it was previously found 8 that astigmatism affects visual acuity more than defocus. Thus the difference between our results and the obtained in that study can be attributed to the different range of blur considered in both cases.…”

Section: Discussionsupporting

confidence: 88%

“…In this sense, a number of studies have not found a strong effect of induced cylinder axis on the changes in VA with astigmatism 19, 20, 21, 22, 23, 30. However, other studies have reported that ATR induced a greater reduction in VA compared to with WTR astigmatism6, 8, 24, 25, 26, 27, 28 and vice versa 25 . Methodological differences in terms of how astigmatism was simulated (with a cross-cylinder, pure positive cylindres, etc.)…”

Section: Discussionmentioning

confidence: 97%

“…Additionally, a number of studies have reported approximately linear variation in logMAR VA with increasing cylinder power but with a different rate of change (slope), depending on the specific methodology adopted, including: the type of acuity chart, age of subjects, presence of active accommodation, correction of higher-order aberrations and the type of astigmatism 5, 6, 8, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. According to the present study, there was a linear reduction in monocular logMAR VA with increasing astigmatic blur in all types of astigmatism considered, but with a different rate of change (see Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…Kobashi et al 27 reported that oblique astigmatism had lower VA and reading performance than those with uncorrected 0° and 90° axis of astigmatism. Atchinson et al 8 found that subjective blur-limits for cylinder at 0° axis, were greater (about 20%) than those for oblique axes. However, in a recent study 28 the same main authors found that VA was affected significantly by the axis of the cylinder, with better VA for 90° than for any other orientation (45°, 135°, and 180°).…”

Section: Introductionmentioning

confidence: 98%

“…However, VA is affected by different extrinsic parameters, such as the design of the optotype chart, its luminance and contrast, since these factors can affect the chart readability 5, 6. Moreover, under the same experimental conditions, intrinsic parameters such as the subject's higher-order aberrations,7, 8 pupil size, 9 accomodation, 10 the level of neural adaptation11, 12, 13 and the subjective perception of blur 14 have been demonstrated to influence the results. More specifically, several studies have investigated the effects of the astigmatism on near and distance VA and/or subject's reading performance.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Influence of different types of astigmatism on visual acuity

Remón

Monsoriu

Furlan

2017

Journal of Optometry

View full text Add to dashboard Cite

PurposeTo investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes.MethodsThe lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength).ResultsLogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response.ConclusionsVA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation.

show abstract

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Influence of different types of astigmatism on visual acuity

Remón

Monsoriu

Furlan

2017

Journal of Optometry

View full text Add to dashboard Cite

show abstract

Induced astigmatism biases the orientation information represented in multivariate electroencephalogram activities

Son

Moon

Kang

et al. 2021

Human Brain Mapping

View full text Add to dashboard Cite

A small physical change in the eye influences the entire neural information process along the visual pathway, causing perceptual errors and behavioral changes. Astigmatism, a refractive error in which visual images do not evenly focus on the retina, modulates visual perception, and the accompanying neural processes in the brain. However, studies on the neural representation of visual stimuli in astigmatism are scarce. We investigated the relationship between retinal input distortions and neural bias in astigmatism and how modulated neural information causes a perceptual error. We induced astigmatism by placing a cylindrical lens on the dominant eye of human participants, while they reported the orientations of the presented Gabor patches. The simultaneously recorded electroencephalogram activity revealed that stimulus orientation information estimated from the multivariate electroencephalogram activity was biased away from the neural representation of the astigmatic axis and predictive of behavioral bias. The representational neural dynamics underlying the perceptual error revealed the temporal state transition; it was transiently dynamic and unstable (approximately 350 ms from stimulus onset) that soon stabilized. The biased stimulus orientation information represented by the spatially distributed electroencephalogram activity mediated the distorted retinal images and biased orientation perception in induced astigmatism.

show abstract

Prescribing Spectacles

Satgunam

2024

Ophthalmic Diagnostics

View full text Add to dashboard Cite

Visual Acuity with Astigmatic Blur

Abstract: Small levels of crossed cylinder blur (≤0.75 D) produces losses in visual acuity that are dependent on the cylinder axis. Crossed cylinders of 0.75 D produce losses in visual acuity that are twice those produced by defocus of the same blur strength.

Cited by 48 publications

References 7 publications

Influence of different types of astigmatism on visual acuity

Influence of different types of astigmatism on visual acuity

Induced astigmatism biases the orientation information represented in multivariate electroencephalogram activities

Prescribing Spectacles

Contact Info

Product

Resources

About