The diagnosis of glaucoma in cross sectional prevalence surveys (The diagnosis is made according to three levels of evidence)
| Category 1 diagnosis (structural and functional evidence) |
| Eyes with a CDR or CDR asymmetry ≥97.5th percentile for the normal population, or a neuroretinal rim width reduced to ≤0.1 CDR (between 11 to 1 o'clock or 5 to 7 o'clock) that also showed a definite visual field defect consistent with glaucoma. |
| Category 2 diagnosis (advanced structural damage with unproved field loss) |
| If the subject could not satisfactorily complete visual field testing but had a CDR or CDR asymmetry ≥ 99.5th percentile for the normal population, glaucoma was diagnosed solely on the structural evidence. |
| In diagnosing category 1 or 2 glaucoma, there should be no alternative explanation for CDR findings (dysplastic disc or marked anisometropia) or the visual field defect (retinal vascular disease, macular degeneration, or cerebrovascular disease). |
| Category 3 diagnosis (Optic disc not seen. Field test impossible) |
| If it is not possible to examine the optic disc, glaucoma is diagnosed if: (A) The visual acuity <3/60 and the IOP >99.5th percentile, or(B) The visual acuity <3/60 and the eye shows evidence of glaucoma filtering surgery, or medical records were available confirming glaucomatous visual morbidity. |