Abstract
Purpose::
To evaluate the sensitivity and specificity by Glaucoma Probability Score (GPS), a new glaucoma diagnosis program in the version 3.0 of Heidelberg Retina Tomograph (HRT) II (Heidelberg Engineering, Dossenheim, Germany) in detecting early glaucoma in East Asian (Japanese) eyes.
Methods::
Sensitivity and specificity by GPS was determined in 152 open-angle glaucoma eyes with mild damage (Humphrey Field Analyzer 30-2 SITA-standard mean deviation > -5dB) of 152 patients, age- and refraction-matched 152 eyes of 152 ophthalmologically normal subjects randomly chosen from a population-based sample of the Tajimi Study1 (N1 group) and 100 eyes of 100 institute-based normal subjects (N2 group). The results by GPS were compared with those by the Moorfields Regression Analysis (MRA) and the FSM discriminant function (FSM). Analysis was also done by stratifying the eyes by refraction, disc area, or ovality of the disc.
Results::
For all glaucoma eyes, sensitivity of GPS (90%) was similar to that of MRA (88%, P=0.5, chi-square test), but was significantly higher than that of FSM (76%, P<0.001). Specificity of GPS (60 and 46% for N1 and N2, respectively) was significantly lower than that of MRA (79 and 75%, P<0.001) or that of FSM (88 and 77%, P<0.001). No significant difference was seen in sensitivity or specificity in the subgroups divided by refraction or ovality of the disc. When stratified by the disc area, specificity was 33 and 31% for N1 and N2, respectively in eyes with disc area ≥ 2mm2 in comparison with 79 and 59%, respectively, in those with disc area < 2mm2 (P<0.001).
Conclusions::
In Japanese eyes, sensitivity by GPS to detect early glaucoma was similar to that of MRA, but higher than that of FSM. Specificity of GPS, however, was considerably lower than that by MRA or FSM, or the results on GPS in Caucasian eyes, especially in eyes with larger disc area. Although GPS may facilitate glaucoma diagnosis, the current results suggest racial difference in morphological characteristics of normal optic discs and necessity of establishing a proper normal database for HRTII targeting the East Asian population.1. Iwase et al. Ophthalmology 2004;111:1641-8.