Abstract
Abstract: :
Purpose: Pilot study to assess progression of localised visual field defects using FOP with two different evaluation methods (CIGTS and modified pointwise linear regression [PLR]) in glaucoma patients / suspects with and without topical Brimonidine therapy. Methods: A total of 24 eyes of 24 glaucoma patients / suspects (13 male, 11 female; age range: 20 to 72 years) were enrolled and randomised for treatment (12 with a treatment regimen that included Brimonidine, and 12 without Brimonidine, respectively). All subjects were followed for > 2.5 years with a minimum of 4 examinations. FOP with the Tuebingen Computer Campimeter (TCC: calibrated, high resolution 20" monitor with a background luminance of 10 cd/m2, covering the central 35° x 24° ["radius"] of the visual field) was used in order to condense test points in visual field areas related to morphologically suspicious regions (e.g. nerve fiber bundle defects, optic disc notches), identified from patients' digitized fundus photographs. Differential luminance sensitivity (dls) was estimated by a maximum likelihood procedure on the basis of a modified 4-2-1 dB strategy. Definition of change (progression / improvement) was as follows: For CIGTS, change by > 3, compared with the average of two baseline fields, and confirmed by two subsequent examinations. For PLR, a change was assumed if a cluster of 3 or more neighbouring (non-edge, non-blind spot) test locations were flagged; combined improvement and progression within a visual field follow-up series was classified as heterogeneous change. Results: 8 eyes in the Brimonidine group, and 11 eyes in the non-Brimonidine group completed the study. In regard to CIGTS score, progression occurred in 0 (0), and improvement in 0 (1) of the patients, respectively (results of the Brimonidine group are shown in brackets). With the modified PLR analysis, progression could be detected in 3 (0), improvement in 1 (4), and heterogeneous change in 0 (2) patients, respectively. Conclusions: In this pilot study, the CIGTS progression criterion appeared to be less sensitive for detecting change than the modified PLR analysis (cluster of 3 flagged test locations). CIGTS score cannot detect heterogeneous change, which - in contrast to (generalised or local) improvement - cannot be assigned to learning effects. Progression of visual field defects tends to be somewhat more frequent in the non-Brimonidine group compared to the Brimonidine group.
Keywords: visual fields • perimetry • neuroprotection