Abstract
Abstract: :
Purpose:To investigate the relationship of central and peripheral perimetry with scanning laser polarimetry (SLP) (GDx VCC; Laser Diagnostic Technologies, San Diego, CA) in previously diagnosed glaucoma subjects that demonstrate peripheral visual field defects. Methods:The data reviewed in this study were from 17 glaucomatous eyes and 5 normal eyes from 11 subjects with glaucoma from an ongoing multi–center study, the Collection of Normative and Glaucoma Values with the GDx VCC. Image quality of the SLP scans were always greater than eight and each eye was imaged three consecutive times to establish the repeatability. Visual field data were collected using the HFA 24–2 and 60–4 programs. All visual field data surpassed the manufacturers reliability indices. All subjects were familiar with automated perimetry having taken at least three prior visual field exams. All testing was performed within a 6 month time period. The SLP average superior RNFL thickness and the average inferior RNFL thickness were compared to the perimetric mean value of the superior and inferior fields. The mean values of the superior and inferior visual fields were also computed for central and peripheral visual fields, individually and collectively. The coefficient of determination (R²) values and the probabilities of random occurrence (P) were computed using a linear regression that assumed that RNFL thickness was a linear predictor of visual threshold sensitivity. All Statistical analysis of data was done using Pearson’s Correlation in JMP Version 4. Results: The average threshold values of peripheral visual fields, (superior R²=0.23) and (inferior R²=0.37), and the combined superior central and peripheral (R2=0.32) were significantly correlated with corresponding RNFL thickness at the confidence (α) level of (P<0.05). All other correlations were not statistically significant. Conclusions: SLP correlates well with peripheral as well as combined central and peripheral visual field evaluation. The most common method of glaucoma detection, SAP of the central visual field, was not shown to identify 36% of these glaucomatous eyes with peripheral visual field defects. This small subgroup of selected subjects suggests that peripheral field defects in the absence of central field defects may be higher than the previously reported 4–11%. Because this study looked at only a small population and the subjects were not randomized, additional research comparing central, peripheral, and combined central/peripheral visual fields and SLP needs to be conducted.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • perimetry • nerve fiber layer