Screening for glaucoma in the Chinese elderly population in Singapore

Aim: To determine the performance of different tests in screening for glaucoma. Method: The results from a glaucoma prevalence study of 479 Chinese elderly Singaporeans were analysed. Glaucoma screening tests evaluated in this study included Goldmann applanation tonometry (GAT), non-contact tonometry (NCT), optic disc assessment, screening Humphrey visual field and gonioscopy. The sensitivity, specificity and positive predictive values of the various screening tests in detecting glaucoma were calculated. Results: The sensitivity of GAT and NCT at a specificity of at least 90% was 26% and 30% respectively with a low positive predictive value (PPV) of 0.13. Optic disc assessment with a vertical cup-disc ratio cut-off of more than 0.7 had a sensitivity of 100% and a specificity of 94% and a PPV of 0.46. The sensitivity of visual fields was 100% with a specificity of 76% and a PPV of 0.17. Gonioscopy had a sensitivity of 100% and specificity of 93% and a PPV of 0.14 in detecting primary angle closure glaucoma. Conclusion: Optic nerve assessment performed better than other glaucoma screening tests. There are, however, many other considerations that need to be taken into account in determining the ideal test for population screening.