A subjective refraction-based assessment of image quality metric

Iskander, D. Robert

doi:10.4302/plp.2011.4.08

Cited by 9 publications

(21 citation statements)

References 20 publications

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“…Very few studies have performed undilated comparisons of the spherical equivalent (M) component of wavefront refractions. Using metrics Iskander found differences in M that ranged between −0.31 and −0.62 D, while, calculating refraction from coefficient terms, Zhu et al . found −0.39 D. The mean difference in M for undilated myopic eyes found here was −0.65 D (and for all eyes was −0.48 D).…”

Section: Discussionmentioning

confidence: 45%

“…Dioptric differences between the two refractions are included here for comparison with other studies, despite the many different metric, wavefront refraction, and subjective refraction methodologies used in the past. However, when stating dioptric values, bear in mind that while a particular VSX value quantifies visual image quality essentially independent of pupil size, a particular dioptric value does not, for instance, −1 D affects vision very differently when viewing through small and large pupils …”

Section: Discussionmentioning

confidence: 99%

“…The method employed identified the SCA combination (sphere and cylinder to the nearest 0.25 D, and axis in 2° increments) that provided the best image quality (VSX) for the measured WFE by performing a simulated through‐focus experiment . All calculations were performed using custom Matlab software (https://www.mathworks.com).…”

Section: Methodsmentioning

confidence: 99%

“…Numerous studies have processed wavefront error measurements using image quality metric methodologies (both metrics of visual image quality and retinal image quality) to identify a SCA prescription. In contrast to methods that use only second‐order or other specific Zernike terms such as primary spherical aberration and coma, metric‐based methods consider the combination of all aberrations in the eye when optimising retinal image quality …”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, given the clinical wisdom that patients can and do adapt to new prescriptions (particularly when the changes are relatively small), such objective methods of refraction would not be influenced by factors that can skew subjective refraction, such as adaptation to a habitual prescription. 12 Numerous studies 5,6,[13][14][15][16][17] have processed wavefront error measurements using image quality metric methodologies (both metrics of visual image quality and retinal image quality) to identify a SCA prescription. In contrast to methods that use only second-order 18,19 or other specific Zernike terms such as primary spherical aberration and coma, 5,20-22 metric-based methods consider the combination 23 of all aberrations in the eye when optimising retinal image quality.…”

Section: Introductionmentioning

confidence: 99%

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Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

Hastings

Marsack

Nguyen

et al. 2017

Ophthalmic Physiologic Optic

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Purpose To prospectively examine whether using the visual image quality metric, visual Strehl (VSX), to optimise objective refraction from wavefront error measurements can provide equivalent or better visual performance than subjective refraction and which refraction is preferred in free viewing. Methods Subjective refractions and wavefront aberrations were measured on 40 visually-normal eyes of 20 subjects, through natural and dilated pupils. For each eye a sphere, cylinder, and axis prescription was also objectively determined that optimised visual image quality (VSX) for the measured wavefront error. High contrast (HC) and low contrast (LC) logMAR visual acuity (VA) and short-term monocular distance vision preference were recorded and compared between the VSX-objective and subjective prescriptions both undilated and dilated. Results For 36 myopic eyes, clinically equivalent (and not statistically different) HC VA was provided with both the objective and subjective refractions (undilated mean ±SD was −0.06 ±0.04 with both refractions; dilated was −0.05 ±0.04 with the objective, and −0.05 ±0.05 with the subjective refraction). LC logMAR VA provided by the objective refraction was also clinically equivalent and not statistically different to that provided by the subjective refraction through both natural and dilated pupils for myopic eyes. In free viewing the objective prescription was preferred over the subjective by 72% of myopic eyes when not dilated. For four habitually undercorrected high hyperopic eyes, the VSX-objective refraction was more positive in spherical power and VA poorer than with the subjective refraction. Conclusions A method of simultaneously optimising sphere, cylinder, and axis from wavefront error measurements, using the visual image quality metric VSX, is described. In myopic subjects, visual performance, as measured by HC and LC VA, with this VSX-objective refraction was found equivalent to that provided by subjective refraction, and was typically preferred over subjective refraction. Subjective refraction was preferred by habitually undercorrected hyperopic eyes.

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Section: Discussionmentioning

confidence: 45%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

Hastings

Marsack

Nguyen

et al. 2017

Ophthalmic Physiologic Optic

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Agreement of wavefront-based refraction, dry and cycloplegic autorefraction with subjective refraction

Bamdad

Momeni‐Moghaddam

Abdolahian

et al. 2022

Journal of Optometry

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Purpose To evaluate the agreement of dry, and cycloplegic autorefraction and wavefront-based refraction with subjective refraction. Method 83 subjects aged 19–57 years were included in this cross-sectional study. Refractive status was determined using four methods including subjective refraction, wavefront-based refraction, dry and cycloplegic autorefraction. Refractive data were recorded as sphere, cylinder and spherical equivalent (SE). Power vector components were used to compare the astigmatism obtained using the different methods of refraction. Results The more negative spherical, cylindrical and SE components were obtained using dry autorefraction, wavefront-based refraction and dry autorefraction, respectively. The less negative spherical, cylindrical and SE components were obtained using cycloplegic autorefraction, subjective refraction and cycloplegic autorefraction, respectively. Considering the spherical component, there was a statistically significant hyperopic shift (0.12 ± 0.29 D, p = 0.001) with cycloplegic autorefraction and a significant myopic shift (−0.17 ± 0.32 D, p < 0.001) with dry autorefraction compared to subjective refraction, while the difference between wavefront-based and subjective refraction was not significant statistically (p = 0.145). The calculated cylindrical component using subjective refraction showed statistically significant difference with dry auto-refraction (p < 0.001), cycloplegic auto-refraction (p = 0.041) and wavefront refraction (p < 0.001). The highest correlation with subjective refraction in sphere, cylinder and SE was observed for cycloplegic auto-refraction (r s = 0.967), dry auto-refraction (r s = 0.983) and cycloplegic auto-refraction (r s = 0.982), respectively. Conclusions As subjective refraction is gold standard in our study, sphere in cycloplegic auto-refraction and astigmatism in dry auto-refraction showed better agreement and correlation.

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Visual Acuity Outcomes in a Randomized Trial of Wavefront Metric-optimized Refractions in Adults with Down Syndrome

Anderson¹,

Marsack

Benoit

et al. 2021

Optom Vis Sci

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show abstract

A subjective refraction-based assessment of image quality metric

Abstract: Abstract-Tools for quantifying image quality should be bench-

Cited by 9 publications

References 20 publications

Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

Agreement of wavefront-based refraction, dry and cycloplegic autorefraction with subjective refraction

Visual Acuity Outcomes in a Randomized Trial of Wavefront Metric-optimized Refractions in Adults with Down Syndrome

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