JH Seo, et al. ASSESSMENT OF FUNCTIONAL VISION SCORE IN RP 0.31×FFS+21.72, (r2=0.40). (Better VA group, n=50), NEI-FVQ composite=1.50×FAS +2.91×FFS-2.78×FVS-86.11 (r2=0.37). (Worse VA group, n=62), NEI-FVQ composite=0.24×FAS +0.23×FFS-2.78+25.8 (r2=0.22). D iscussio n Our results indicate that in RP patients, BCVA and the AMA guidelines’ FVS, FFS, and FAS are equally correlated to those of the self-reported VFQ. Several other studies6,12 evaluating the performance of RP patients demonstrated that reading per- formance correlates with contrast sensitivity, VA, and visual field, while driving performance is the primary correlate of visual field loss. In fact, one of the conclusions of the work is that FVS is no better than BCVA (correlation: 0.60) for cate- gorizing RP patients in terms of self-perceived QOL. This can be expected since the visual functioning of RP patients can be estimated from BCVA on average, although contrast sensitivity may add information. To assess performance function, several studies7-9 utilized questionnaires or AMA guidelines for FVS. According to the results, the VFQ is a reliable, valid method that should be use- ful for group-level comparisons of vision-specific quality of life in clinical research. The FVS has also been found to be a potent predictor of self-reported vision-specific quality of life. However, these studies9,13,14 did not focus on RP patients. Our study confirmed that the BCVA, FVS, FAS and FFS are highly correlated to the VFQ in RP patients. In accordance with our results, Szlyk et al. found that self-reporting is strongly correlated with actual task performancein RP patients.5 The group evaluated the correlation of reading composite scores with contrast sen- sitivity, whereas, in our study, we used the AMA’s FVS and VFQ composite score. However, compared with BCVA and FVS, it suggests that the FVS may not add much to the value of basic measures of visual function in some diseases. We could comment on previous research on the FVS in other diseases or in the general population, such as the study by Rubin et al.15 who stated that monocular acuity and binocular acuity are significantly better predictors of reading speed than the AMA weighted score or a recently proposed Functional Vision Score (FVS). In this study, the VFQ was affected by both the FFS and the FAS, although the regression equation had an interactive form (FVS). We speculate that these findings might reflect the fact that RP is a disease manifesting with progressive visual field loss. A hallmark feature of RP is an insidious, progressive loss of peripheral visual field. The peripheral island of visual field is lost before the central visual field contracts. Therefore, the remaining, functional field is important in advanced RP patients, as FFS represents visual field in the worse VA group. However, we cannot estimate the rate of visual field progression from our results, though Berson et al. suggested that the visual field is lost at a rate of about 4.6% per year.16 Massof et al. proposed that the visual field diminishes approximately 50% over 4.5 years.17 In any case, the rate of progression of visual field loss is usually slow and relentless in RP patients. The limitations of this study include its cross-sectional de- sign, which does not allow for the assessment of the RP course. Because the enrolled patients presented with various stages of RP, selection bias could be an issue. Despite these limitations, our study is the first to determine the correlation of FVS to vision-specific quality of life in a relatively large group of RP patients. In conclusion, the vision-specific quality of life correlated with the AMA’s guidelines with FVS, FFS and FAS in RP patients. The correlations to the NEI-FVQ were not different. 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