Glaucoma screening using the scanning laser polarimeter

To determine the ability of scanning laser polarimetry (GDx Nerve Fiber Analyzer; Laser Diagnostic Technologies, Inc., San Diego, CA) to separate normal eyes and those considered likely to have glaucoma in a public glaucoma screening.

A 2-day public glaucoma screening program was held at two different institutions. Each subject underwent ophthalmologic examination, Humphrey perimetry (24-2 Fastpac program), and imaging using scanning laser polarimetry (GDx) in each eye for allocation into a diagnostic category: normal, ocular hypertensive, glaucoma suspect, or glaucoma. Results from the normal and glaucoma groups were analyzed, using modulation parameters calculated from a measurement band located 1.8 disc diameters from the disc, and selected parameters provided automatically by GDx software. Receiver operating characteristic curves were used to depict the sensitivity/specificity relationship at different GDx parameter cutoff levels.

Of 200 subjects, 197 were classified; 122 were classified as normal, 23 were classified with ocular hypertension, 30 were classified as glaucoma suspects, and 22 were classified with definite glaucoma. Three subjects had ocular diseases other than glaucoma. The maximum area under the receiver operating characteristic curve for modulation parameters was 0.935, and for the GDx software parameters was 0.901.

Scanning laser polarimetry may be useful in glaucoma screening.