Relationship between the full-field stimulus test and self-reported visual function in patients with retinitis pigmentosa: REPEAT Study report No. 3.

PURPOSE

To determine the relationship between the full-field stimulus test (FST) and self-reported visual function using the Michigan Retinal Degeneration Questionnaire (MRDQ) in patients with retinitis pigmentosa (RP).

METHODS

In this cross-sectional study, patients with clinically diagnosed RP (n = 31) performed FST to determine retinal sensitivity thresholds for blue, red and white stimuli. The difference between the blue and red thresholds was used to identify photoreceptor mediation type. Patients completed the MRDQ from which disability (Θ) scores were derived across seven visual function domains. Correlations between the FST thresholds and MRDQ domain Θ-scores were analysed using Spearman's rank correlation.

RESULTS

The median age was 38.0 years, and photoreceptor mediation was rod-based in 11 patients (35.5%), cone-based in seven patients (22.6%) and mixed in 13 patients (41.9%). The highest disability scores were reported in the domains of 'mesopic peripheral function' and 'scotopic function'. Significant correlations were found between all chromatic stimuli thresholds and the MRDQ domains of 'scotopic function', 'mesopic peripheral function' and 'photopic peripheral function'. The strongest correlations of these domains were observed with the blue FST (p < 0.001). The threshold on blue stimulus FST and age were significant predictors of the domain scores on 'scotopic function' (p < 0.001), 'mesopic peripheral function' (p < 0.001) and 'photopic peripheral function' (p < 0.001).

CONCLUSIONS

Strong correlations between MRDQ domains related to rod function and FST were found in patients with RP. These findings confirm that FST can be used as an informative and clinically relevant endpoint in RP trials when evaluating therapeutic interventions.