Vision test variability in retinitis pigmentosa and psychosocial factors

Purpose. We explored whether greater amounts of short-term variability in visual acuity (VA), contrast sensitivity (CS), or visual field (VF) in retinitis pigmentosa (RP) was related to disease severity or psychosocial factors. Methods. We obtained spectral domain-optical coherence tomography in 27 RP subjects and determined variability (SD) of VA, CS, and VF during a mean of 16 tests self-administered at home on a personal computer twice a week. Subjects completed the Positive and Negative Affect Schedules at each personal computer-test session, and SF-36 general health and Beck Depression Inventory questionnaires on one occasion. Results. There was a 0.10 log unit increase in VA variability for every 0.58 logMAR increase (worse mean VA) (p = 0.001). For subjects with reduced foveal thickness, mean VA explained more of the total VA variability than foveal thickness (R = 0.72 and 0.46, respectively, in simple linear regressions). There was a statistically significant 4.3% increased log VF area variability for every 50% mean log VF area decrease (p < 0.001); explaining most of the total variability in log VF area variability (R = 0.44). When controlling for mean log VF area, there was a statistically significant increase in log VF area variability for subjects with greater than minimal depressive symptoms (p = 0.015), with increased mean irritability scores (p = 0.02), decreased SF-36 physical functioning subscale scores (p = 0.03), or decreased mean score for feeling active, strong, and proud (p = 0.008) (adjusted R = 0.62). CS variability was low and not statistically significantly related to mean CS, macular thickness, or psychosocial factors. Conclusions. Increased VA and VF variability was predicted largely by increased RP severity. Greater VF variability occurred in subjects with reduced VF who reported less physical activity or increased negative psychosocial states. These associations should be considered during clinical examinations and trials for RP.