Oman Eye Study 2005: validity of screening tests used in the glaucoma survey.

We carried out a validity assessment study for glaucoma screening procedures used during the survey conducted in Oman in 2005 on 6644 eyes in 3324 people > or = 30 years. Ocular pressure and fundus changes were the screening parameters used: glaucoma was found in 433 eyes. Sensitivity for ocular pressure was 49.7% and specificity 95.6%. For optic disc changes, sensitivity was 48.4% and specificity 97.9%. Combining both through parallel testing, sensitivity improved to 67.3% and specificity to 96.5%. An eye may, thus, be declared as not having glaucoma, but cannot be labelled as having glaucoma, using these parameters.