Value of logistic discriminant analysis for interpreting initial visual field defects.

PURPOSE

The authors evaluate logistic discriminant analysis as a method for interpreting visual field results in initial stages of several ophthalmic diseases.

METHODS

The authors retrospectively studied the visual field defects of 96 patients with early glaucomatous damage and prospectively studied 84 subjects with normal eyes (n = 28), cataracts (n = 27), diabetic retinopathy (n = 14), or hypertensive retinopathy (n = 15). The visual fields were examined at least twice with program G1 of Octopus 500 (Interzeag AG, Schlieren, Switzerland). Only one eye per patient was randomly selected and included in the study. The authors created a database with all visual field information provided by Octopus and applied logistic discriminant analysis (SAS Logistic Procedures, SAS Institute, Cary, NC) to obtain classification rules capable of qualifying visual field defects as glaucomatous or nonglaucomatous. The rules were tested with an independent sample.

RESULTS

There were significant differences between the groups in the distribution of visual field defects tested by program G1. Logistic discriminant analysis correctly identified the glaucomatous or nonglaucomatous origin of the defects with a sensitivity of 65% to 85% and a specificity of 60% to 92%.

CONCLUSIONS

Logistic discriminant analysis is a useful tool to aid in the interpretation of early glaucomatous and nonglaucomatous visual field defects.