Visual acuity and its measurement

Kniestedt, Christoph; Stamper, Robert L.

doi:10.1016/s0896-1549(03)00013-0

Cited by 154 publications

(116 citation statements)

References 15 publications

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“…[7][8][9][10][11] It has also been noted that the VA measurements in a healthy subject can be overestimated by increasing contrast levels. 12 One of the ways to analyze contrast is by measuring contrast ratio, which is the ratio of an image's maximum luminance to its minimum luminance.…”

Section: Discussionmentioning

confidence: 99%

Effectiveness of a smartphone application for testing near visual acuity

Tofigh

Shortridge

Elkeeb

et al. 2015

Eye

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Purpose The purpose of this study was to evaluate the discrepancy between the near visual acuity (VA) measurements using the EyeHandBook smartphone application and the conventional method of using the near vision card. Methods Using similar environmental/ examinational conditions, near VA measurements were obtained and compared using the near vision card and the EyeHandBook app for IPhone 5 from 100 subjects. The obtained data were changed to LogMAR format and the relationship between the two techniques was analyzed by paired sample t-test and scatterplot. Results With a P-value ofo0.0001, our results indicate that the EyeHandBook application running on IPhone 5 overestimates the near VA compared with the conventional near vision card by an average of 0.11 LogMAR unless the measurement done by the near vision card was 20/20. Conclusions Owing to vast utilization of portable high-definition screens in VA measurements, eye-care providers have to be mindful of the potential disparity in VA measurement between different platforms, which in our study was likely secondary to the high contrast and brightness levels of the smartphone's high-definition screen when compared with the near vision card.

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Section: Discussionmentioning

confidence: 99%

Effectiveness of a smartphone application for testing near visual acuity

Tofigh

Shortridge

Elkeeb

et al. 2015

Eye

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“…Impaired scores on the OFM protocol are found also in cases of recovered visual acuity (i.e. visual acuity ≥ 20/25 11 ; p=0.01 in comparison to controls), suggesting that this measurement is more sensitive to identify patients' persisting visual complains. As seen in Figure 1, the scores of all but one of the affected eyes are placed outside the normal range (defined as ±2.5 SD from controls' mean).…”

Section: Ofm Protocolmentioning

confidence: 98%

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients

Raz

Hallak

Ben‐Hur

et al. 2014

JoVE

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“…However, the Snellen chart has been criticized for optical inconsistencies. 13 Although alternate charts such as logMAR charts are available for use in ophthalmic research, 14,15 the familiarity and availability of the 6-m Snellen chart in hospital and primary care settings have enabled the Snellen chart to remain the most popular and routinely used measure of visual acuity in clinical practice. As such, this study uses the Snellen acuity chart as a baseline comparative chart.…”

Section: Introductionmentioning

confidence: 99%

The Eye Phone Study: reliability and accuracy of assessing Snellen visual acuity using smartphone technology

Perera

Chakrabarti

Islam

et al. 2015

Eye

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Purpose Smartphone-based Snellen visual acuity charts has become popularized; however, their accuracy has not been established. This study aimed to evaluate the equivalence of a smartphone-based visual acuity chart with a standard 6-m Snellen visual acuity (6SVA) chart. Methods First, a review of available Snellen chart applications on iPhone was performed to determine the most accurate application based on optotype size. Subsequently, a prospective comparative study was performed by measuring conventional 6SVA and then iPhone visual acuity using the 'Snellen' application on an Apple iPhone 4. Results Eleven applications were identified, with accuracy of optotype size ranging from 4.4-39.9%. Eighty-eight patients from general medical and surgical wards in a tertiary hospital took part in the second part of the study. The mean difference in logMAR visual acuity between the two charts was 0.02 logMAR (95% limit of agreement − 0.332, 0.372 logMAR). The largest mean difference in logMAR acuity was noted in the subgroup of patients with 6SVA worse than 6/18 (n = 5), who had a mean difference of two Snellen visual acuity lines between the charts (0.276 logMAR). Conclusion We did not identify a Snellen visual acuity app at the time of study, which could predict a patients standard Snellen visual acuity within one line. There was considerable variability in the optotype accuracy of apps. Further validation is required for assessment of acuity in patients with severe vision impairment.

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Visual acuity and its measurement

Cited by 154 publications

References 15 publications

Effectiveness of a smartphone application for testing near visual acuity

Effectiveness of a smartphone application for testing near visual acuity

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients

The Eye Phone Study: reliability and accuracy of assessing Snellen visual acuity using smartphone technology

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