Visual Acuity with Simulated and Real Astigmatic Defocus

Ohlendorf, Arne; Tabernero, Juan; Schaeffel, Frank

doi:10.1097/opx.0b013e31821281bc

Cited by 45 publications

(43 citation statements)

References 28 publications

(24 reference statements)

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“…To measure retinal images at the posterior focal line in astigmatic eyes, no spherical lenses were used to compensate for cylindrical powers. 4,6,7,11,12 The effects of the axis orientations were assessed with the 3 types of plus cylinder-oriented axes (WTR, Â180; ATR, Â90; OBL, Â135).…”

Section: Visual Acuity and Reading Performancementioning

confidence: 99%

“…A refraction of no astigmatism served as a control. The 3.0 mm artificial pupil was placed in a trial frame and was centered on the pupil of the noncycloplegic testing eye for each subject using a video technique described by Ohlendorf et al 11 All pupils were dilated to at least 6.0 mm after cycloplegia. To measure retinal images at the posterior focal line in astigmatic eyes, no spherical lenses were used to compensate for cylindrical powers.…”

Section: Visual Acuity and Reading Performancementioning

confidence: 99%

“…Many studies [4][5][6][7][8][9][10][11][12][13] have assessed the comparability of visual acuity or contrast sensitivity between with-the-rule (WTR) astigmatism, against-the-rule (ATR) astigmatism, and oblique (OBL) astigmatism. However, to our knowledge, there are no detailed clinical studies of the impact of axis orientation on reading performance with different amounts of astigmatism.…”

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confidence: 99%

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Effect of axis orientation on visual performance in astigmatic eyes

Kobashi¹,

Kamiya²,

Shimizu³

et al. 2012

Journal of Cataract and Refractive Surgery

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Section: Visual Acuity and Reading Performancementioning

confidence: 99%

Section: Visual Acuity and Reading Performancementioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Effect of axis orientation on visual performance in astigmatic eyes

Kobashi¹,

Kamiya²,

Shimizu³

et al. 2012

Journal of Cataract and Refractive Surgery

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show abstract

“…It is known that horizontal blur of letters has a greater impact on legibility than other orientations [4,10,46] and that neural adaptations, affecting clear vision determination and blur sensitivity, may occur in the presence of astigmatism [47][48][49]. However, in the present study, we measured UDVA with a Landolt ring, not a letter chart.…”

Section: Discussionmentioning

confidence: 81%

Influence of simple myopic against-the-rule and with-the-rule astigmatism on visual acuity in eyes with monofocal intraocular lenses

Yamamoto¹,

Hiraoka

Beheregaray

et al. 2014

Jpn J Ophthalmol

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“…At first Ohlendorf et al (2011a) visual acuity at previously mentioned rate (20%, 50%, and 75%) was less (exact amount of defocus was not reported) than real spherical defocus in the first experiment. In the second and third experiments, there was 40 to 60% less requirement of the simulated astigmatic and cross cylinder blur to reduce visual acuity (20%, 50% and 75% rate) than the real astigmatic and cross cylinder blur.…”

Section: Blur Adaptation With Source and Observer Methodsmentioning

confidence: 99%

Blur Adaptation with Source and Observer Methods

Sarkar¹

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Blur adaptation is the improvement of visual and perceptual performance with time following viewing of a target blurred by some combination of defocus, astigmatism and higher-order aberrations. Blurred images can be produced by two different methods -source and observer. In the source method, image convolution between the point spread function of intended aberration and object produces blurred images on a display screen. In the observer method, the blurred images are produced optically such as by deformable mirrors. Previous studies on higher-order aberration blur adaptation were restricted to the source method. This study compared blur adaptation between source and observer methods for combinations of defocus and higher-order aberrations. It is important to compare blur adaptation with source and observer methods as the first one blurred the stimulus not the surroundings while the second one blurred both the stimulus and surroundings. On the basis that the observer method has phase information lacking in the source method, the main hypothesis of the study was that blur adaption would be greater with the observer method than with the source method.A custom built adaptive optics system had three channels -an illumination channel, an adaptive optics control channel with deformable mirror and Hartmann-Shack wavefront sensor, and a psychophysical channel with a display. Blurred images of a natural scene (adapting images) and tumbling Es (testing images) were generated for +2 D, −2 D and 0 D defocus with and without higher order aberrations of the eye. Five participants performed a four alternative forced choice procedure with the method of constant stimuli to obtain visual acuity. They adapted to the natural scene for 1 minute, followed by testing images for 1 second, and refreshing of the adapting image for 3 seconds.In the source method, mean ± SEM of visual acuities were 0.42 ± 0.08 logMAR without blur adaptation and 0.39 ± 0.09 logMAR with blur adaptation, giving a small, but statistically significant improvement of 0.03 ± 0.01 logMAR (p = 0.03) with blur adaptation. In the observer method, mean ± SEM of visual acuities were 0.16 ± 0.12 logMAR without blur adaptation and 0.15 ± 0.13 logMAR with blur adaptation, giving a non-significant difference of 0.01 ± 0.03 logMAR (p = 0.77). The mean ± SEM of difference in visual acuity improvement after blur adaptation between source and observer method was not significant at 0.02 ± 0.02 logMAR (p = 0.37). Visual acuities were always better with the observer method than with the source method.Blur adaptation found with both source and observer methods and the comparison of blur adaptation between source and observer methods was not significant. A longer adapting period might be necessary to achieve significant visual acuity improvement following blur adaptation. Replacement of the method of constant stimuli with an adaptive psychophysical procedure such as QUEST (Quick Estimate by iii Sequential Testing) or PEST (Parametric Estimate by Sequential Testing) will shor...

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Visual Acuity with Simulated and Real Astigmatic Defocus

Cited by 45 publications

References 28 publications

Effect of axis orientation on visual performance in astigmatic eyes

Effect of axis orientation on visual performance in astigmatic eyes

Influence of simple myopic against-the-rule and with-the-rule astigmatism on visual acuity in eyes with monofocal intraocular lenses

Blur Adaptation with Source and Observer Methods

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