Detectability of Visual Field Defects in Glaucoma With High-resolution Perimetry

Purpose: To extrapolate the optimal test point resolution for assessment of glaucomatous visual field (VF) defects including subtle functional defects, we performed high-resolution perimetry with the 0.5 degrees test point resolution. Subjects and Methods: Subjects were 11 eyes of 11 normal volunteers and 16 eyes of 16 glaucomatous patients. Octopus 900 custom test was used to measure 61 points with the test point resolution of 0.5 degrees on the temporal meridian of 45 degrees within the eccentricity of 30 degrees. In the glaucoma cases, VF profiles were extracted in 17 patterns of the test point resolutions that ranged from 0.5 to 8.5 degrees and the mean defect (MD), square root of loss variance (sLV), and maximum sensitivity loss (Max loss) were calculated. The influence of the test point resolution on MD, sLV, and Max loss was examined. In addition, the test range from the fixation point to the eccentricity of 30 degrees was divided into 3 zones. Similarly, each zone was investigated if the test point resolution exerted influence on the MD, sLV, and Max loss. Results: Our glaucoma cases did not show any significant differences in MD and sLV regardless of the resolution. Max loss showed significant difference at resolution >= 1.0 degree. MD and sLV did not show significant differences by the change of resolution in each zone. Max loss showed significant differences at resolution >= 1.5 degrees within the central 10 degrees. Conclusions: To detect subtle VF defects within the eccentricity of 10 degrees, high-resolution perimetry with the test point resolution of < 1.5 degrees is necessary.