Population and high-risk group screening for glaucoma: the Los Angeles Latino Eye Study

Abstract

Purpose: To evaluate the ability of various screening tests, both individually and in combination, to detect glaucoma in the general Latino population and high-risk subgroups.

Methods: The Los Angeles Latino Eye Study is a population-based study of eye disease in Latinos 40 years of age and older. Participants (n = 6082) underwent Humphrey visual field testing (HVF), frequency doubling technology (FDT) perimetry, measurement of intraocular pressure (IOP) and central corneal thickness (CCT), and independent assessment of optic nerve vertical cup disc (C/D) ratio. Screening parameters were evaluated for three definitions of glaucoma based on optic disc, visual field, and a combination of both. Analyses were also conducted for high-risk subgroups (family history of glaucoma, diabetes mellitus, and age ≥65 years). Sensitivity, specificity, and receiver operating characteristic curves were calculated for those continuous parameters independently associated with glaucoma. Classification and regression tree (CART) analysis was used to develop a multivariate algorithm for glaucoma screening.

Results: Preset cutoffs for screening parameters yielded a generally poor balance of sensitivity and specificity (sensitivity/specificity for IOP ≥21 mm Hg and C/D ≥0.8 was 0.24/0.97 and 0.60/0.98, respectively). Assessment of high-risk subgroups did not improve the sensitivity/specificity of individual screening parameters. A CART analysis using multiple screening parameters-C/D, HVF, and IOP-substantially improved the balance of sensitivity and specificity (sensitivity/specificity 0.92/0.92).

Conclusions: No single screening parameter is useful for glaucoma screening. However, a combination of vertical C/D ratio, HVF, and IOP provides the best balance of sensitivity/specificity and is likely to provide the highest yield in glaucoma screening programs.

Figure 1.

ROC curves for continuous parameters identified as independently associated with a diagnosis of glaucoma based on characteristic glaucomatous optic nerve and visual field changes.

Figure 2.

Sensitivity and specificity for continuous parameters identified as independently associated with a diagnosis of glaucoma based on both a characteristic glaucomatous optic nerve and visual field: (A) IOP, (B) CCT, (C) vertical C/D ratio. Solid line: sensitivity; dotted line: specificity.

Figure 3.

CART algorithm for screening for glaucoma. The vertical C/D ratio with a cutoff of 0.7 was identified as the best initial parameter for classifying individuals as likely to have glaucoma or nonglaucoma. Those with vertical C/D ratio <0.7 are then further classified according to whether they had a normal versus abnormal visual field. Those with normal visual field are classified as not having glaucoma. Those with an abnormal visual field are further separated into those with IOP <14 mm Hg (classified as not having glaucoma) or those with IOP ≥14 mm Hg (classified as having glaucoma). Participants with vertical C/D ratio ≥0.7 are classified according to HVF analyzer GHT results. Those with abnormal GHT were classified as having glaucoma, whereas those with normal GHT are further classified by expert visual field assessment as normal (not having glaucoma) or abnormal (having glaucoma). The algorithm illustrated here has both a sensitivity and specificity of 0.92. Fifty-two participants are not included in this analysis due to missing data on one or more of the parameters.