Abstract
Purpose: :
Visual acuity (VA) and contrast sensitivity (CS) measures are 2-3 times more variable in legally blind retinitis pigmentosa (RP) patients with VA <20/40 than in normally sighted individuals. RP patients indicate that variations in vision are often related to stress or fatigue, however these associations have not been formally tested previously.
Methods: :
Pilot data from 7 RP subjects were obtained with PC-based binocular VA, CS and visual field (VF) tests performed at home at randomized times, twice weekly for 8 weeks, for a total of 12-16 measures per subject. Subjects’ VA ranged from 0.0 to 1.4 logMAR and all had a VF diameter <20° in the better eye. Prior to each vision test session, subjects indicated if their vision was the same as usual, or slightly better or worse than usual. Data regarding possible associations with perceived stress or sleepiness were obtained with PC-based administration of validated questionnaires after each vision test session.
Results: :
At times when subjects indicated that vision was slightly worse than usual, VA was on average statistically significantly lower by 0.11 logMAR (95% CI: 0.03, 0.19; p=0.007), while CS (average decrease of 0.15 logCS; 95% CI: -0.36, 0.06; p=0.17) and VF (average change of 0.0mm2; 95% CI: -0.001, 0.001; p=0.89) did not statistically significantly vary with the vision ratings. We found a statistically significant relationship between sleepiness and reduced CS by 0.15 logCS on average (95% CI: 0.095, 0.20; p<0.001), but measured VA (average decrease of 0.005 logMAR; 95% CI: -0.07, 0.06; p=0.88) and VF (average decrease of 7.2mm2; 95% CI: -0.37, 14.7; p=0.06) were not statistically significantly associated with sleepiness. At times when subjects indicated that their vision was worse than usual, there was a 95% reduction in the odds of being wide awake versus some sleepiness (95% CI: -4.47, -1.46; p<0.001). There was a statistically significantly decrease in VA associated with increases in the perceived stress scale score in 3 of 7 subjects who had a wide range of stress levels, but CS and VF were not related to stress.
Conclusions: :
These preliminary data suggest that vision and psychosocial factors may be related to each other; in particular, associations of VA with stress, and sleepiness with CS are proposed. Further work is needed to establish a better scientific understanding of these relationships and create a profile of RP patients who are most susceptible to these fluctuations.
Keywords: retinitis • low vision