Table 5

Evaluation of teachers' eye screening results and of the ophthalmic nursing officer's (ONO) performance

True prevalence Sensitivity(%) Specificity(%) PPV (%) NPV (%)
Teachers' uni/bilateral VA <6/12 v bilateral VA <6/12 by eye team0.7270.097.014.999.8
Teachers' uni/bilateral VA <6/12 or poor distance eyesight reported to teachers v bilateral VA <6/12 by eye team0.7280.091.46.599.8
Eye abnormality reported by ONO v ophthalmologist's results 10.092.3100.0100.099.2
  • Based on 130 of the pupils examined by the ONO who were also examined by the ophthalmologist, who was unaware of the ONO's results.

  • Sensitivity: the proportion of children defined as having the condition by the reference test (eg, eye abnormality reported by the ophthalmologist) who were also defined as having the condition by the screening test (eg, eye abnormality reported by the ONO).

  • Specificity: the proportion of children defined as not having the condition by the reference test (eg, no eye abnormality reported by the ophthalmologist) who were also defined as not having the condition by the screening test (eg, no eye abnormality reported by the ONO).

  • PPV (positive predictive value): the proportion of children defined as having the condition by the screening test (eg, eye abnormality reported by the ONO) who were also defined as having the condition by the reference test (eg, eye abnormality reported by the ophthalmologist).

  • NPV (negative predictive value): the proportion of children defined as not having the condition by the screening test (eg, no eye abnormality reported by the ONO) who were also defined as not having the condition by the reference test (eg, no eye abnormality reported by the ophthalmologist).