Computerized repeating and averaging improve the test-retest variability of ETDRS visual acuity measurements

implications for sensitivity and specificity

Nilpa Shah, D Alistair H Laidlaw, Shaheen P Shah, Selvaraj Sivasubramaniam, Catey Bunce, Simon Cousens

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Purpose. The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change.

Methods. Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95% ranges for TRV.

Results. The 95% TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13% (95% CI, 8%–21%) with the ETDRS chart and 4% (95% CI, 2%–10%) with CAMM6 measurements. To achieve ≥95% test sensitivity (assuming 95% test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart.

Conclusions. Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.
Original languageEnglish
Pages (from-to)9397-9402
Number of pages6
JournalInvestigative Ophthalmology & Visual Science
Volume52
Issue number13
Early online date14 Oct 2011
DOIs
Publication statusPublished - 9 Dec 2011

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Visual Acuity
Sensitivity and Specificity
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Keywords

  • adolescent
  • adult
  • aged
  • aged, 80 and over
  • automatic data processing
  • female
  • follow-up studies
  • humans
  • male
  • middle aged
  • reproducibility of results
  • sensitivity and specificity
  • vision disorders
  • vision tests
  • visual acuity
  • young adult

Cite this

Computerized repeating and averaging improve the test-retest variability of ETDRS visual acuity measurements : implications for sensitivity and specificity. / Shah, Nilpa; Laidlaw, D Alistair H; Shah, Shaheen P; Sivasubramaniam, Selvaraj; Bunce, Catey; Cousens, Simon.

In: Investigative Ophthalmology & Visual Science, Vol. 52, No. 13, 09.12.2011, p. 9397-9402.

Research output: Contribution to journalArticle

Shah, Nilpa ; Laidlaw, D Alistair H ; Shah, Shaheen P ; Sivasubramaniam, Selvaraj ; Bunce, Catey ; Cousens, Simon. / Computerized repeating and averaging improve the test-retest variability of ETDRS visual acuity measurements : implications for sensitivity and specificity. In: Investigative Ophthalmology & Visual Science. 2011 ; Vol. 52, No. 13. pp. 9397-9402.
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abstract = "Purpose. The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change.Methods. Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95{\%} ranges for TRV.Results. The 95{\%} TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13{\%} (95{\%} CI, 8{\%}–21{\%}) with the ETDRS chart and 4{\%} (95{\%} CI, 2{\%}–10{\%}) with CAMM6 measurements. To achieve ≥95{\%} test sensitivity (assuming 95{\%} test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart.Conclusions. Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.",
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AU - Shah, Nilpa

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AU - Sivasubramaniam, Selvaraj

AU - Bunce, Catey

AU - Cousens, Simon

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N2 - Purpose. The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change.Methods. Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95% ranges for TRV.Results. The 95% TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13% (95% CI, 8%–21%) with the ETDRS chart and 4% (95% CI, 2%–10%) with CAMM6 measurements. To achieve ≥95% test sensitivity (assuming 95% test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart.Conclusions. Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.

AB - Purpose. The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change.Methods. Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95% ranges for TRV.Results. The 95% TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13% (95% CI, 8%–21%) with the ETDRS chart and 4% (95% CI, 2%–10%) with CAMM6 measurements. To achieve ≥95% test sensitivity (assuming 95% test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart.Conclusions. Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.

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KW - adult

KW - aged

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KW - follow-up studies

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KW - male

KW - middle aged

KW - reproducibility of results

KW - sensitivity and specificity

KW - vision disorders

KW - vision tests

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JO - Investigative Ophthalmology & Visual Science

JF - Investigative Ophthalmology & Visual Science

SN - 0146-0404

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