Standard Automated Perimetry: Determining Spatial Summation and Its Effect on Contrast Sensitivity Across the Visual Field

摘要： PURPOSE. To establish Ricco’s critical area (Ac) using the 30-2 Humphrey visual ?eld analyzer (HVFA) and thereby identify Goldmann test sizes that are within or outside complete spatial summation at all visual ?eld testing locations. We also determined the suitability of using age normative data for different test sizes. Finally, by modifying current output measures (dB values), we provide a new method that allows comparison of contrast sensitivity when testing with different Goldmann test sizes within complete spatial summation. METHODS. We used the HVFA in full threshold mode and measured thresholds for all ?ve Goldmann test sizes in 12 observers. Normative data of Heijl et al. were used for age transformation and comparison. RESULTS. All the data converted to a 50-year-old equivalent lie within 1 SD of expected variance for all test locations of the 30-2 paradigm. We established Ac values at all locations of the 30-2 paradigm and showed a systematic increase in Ac as a function of increased visual ?eld eccentricity, consistent with previous studies. Age does not appear to affect Ac or the slope of partial summation for a wide range of visual ?eld eccentricities tested using the HVFA. By equating spatial summation, we propose a new metric, dB*, that returns a uniform sensitivity value for different test sizes that are operating within complete spatial summation (i.e., follow Ricco’s law). CONCLUSIONS. We established that converting to age-equivalent thresholds and application of dB* principle advantageously allows comparison of data sets across age and test size at different locations of the visual ?eld. By identifying the Ac across the visual ?eld, it is now possible to systematically determine threshold changes across the 30-2 locations in ocular disease and further characterize the importance of testing within complete spatial summation in standard automated perimetry.