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Defining myopia using refractive error and uncorrected logMAR visual acuity >0.3 from 1334 Singapore school children ages 7–9 years
  1. H-D Luo1,
  2. G Gazzard3,
  3. Y Liang1,
  4. A Shankar4,
  5. D TH Tan1,2,5,
  6. S-M Saw1,4,5
  1. 1Singapore Eye Research Institute, Republic of Singapore
  2. 2Singapore National Eye Center, Republic of Singapore
  3. 3The Institute of Ophthalmology, UK
  4. 4Department of Community, Occupational and Family Medicine, National University of Singapore, Republic of Singapore
  5. 5Department of Ophthalmology, National University of Singapore, Republic of Singapore
  1. Correspondence to: Saw Seang Mei Department of Community, Occupational and Family Medicine, National University of Singapore, 16 Medical Drive, Singapore 117597, Republic of Singapore; cofsawsm{at}nus.edu.sg

Abstract

Aim: To determine the association of spherical equivalent (SE) with low uncorrected visual acuity (VA) along with a proposed definition for myopia using logMAR VA >0.3 as the criteria.

Methods: 1334 Chinese schoolchildren (mean age 7.8; range 7–9 years) were enrolled in the study after those who had hyperopia ⩾+2.00 dioptres (D) and astigmatism > = −2.00D were excluded. Uncorrected logMAR VA was measured for both eyes. Cycloplegia autorefraction was achieved by the instillation of three drops of 1% cyclopentolate 5 minutes apart. The average of five successful consecutive refraction and keratometry readings were obtained with calibrated Canon RK5 autokeratorefractometers by well trained optometry students, at least 30 minutes after the instillation of the third drop of cyclopentolate. SE cut-off points (−0.25D, −0.5D, −0.75D, −1.0D) were evaluated.

Results: Using different SE cut-off points, the myopia prevalence rates of this sample of schoolchildren varied from 45.8% (SE at least −0.25 D) to 30.7% (SE at least −1.0 D). The cut-off point of ⩾−0.75 D had a sensitivity and specificity of 91.8% (95% CI, 89.2 to 94.4) and 93.7% (95% CI, 92.1 to 95.3), respectively, to predict low vision defined as uncorrected logMAR VA > 0.3 (either eye). The next best cut-off point of −0.5D had a higher sensitivity (93.3%), but lower specificity (87.9%).

Conclusions: The cut-off points of −0.75D and −0.5D in SE refraction are appropriate for the prediction of uncorrected logMAR VA worse than 0.3, which is the criterion for the US common state adult driver licensing standard.

  • CLEERE, Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study
  • NPV, negative predictive values
  • OLSM, Orinda Longitudinal Study of Myopia
  • PPV, positive predictive values
  • RESC, Refractive Error Study in Children
  • ROC, receiver operating characteristic
  • SCORM, Singapore Cohort Study of Risk Factors for Myopia
  • SE, spherical equivalent
  • VA, visual acuity
  • myopia
  • children
  • Singapore
  • CLEERE, Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study
  • NPV, negative predictive values
  • OLSM, Orinda Longitudinal Study of Myopia
  • PPV, positive predictive values
  • RESC, Refractive Error Study in Children
  • ROC, receiver operating characteristic
  • SCORM, Singapore Cohort Study of Risk Factors for Myopia
  • SE, spherical equivalent
  • VA, visual acuity
  • myopia
  • children
  • Singapore

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