Purpose: This study explored whether the location of photopsias (spontaneous phosphenes) in retinitis pigmentosa (RP) is related to the severity of vision loss, as has been suggested.
Methods: Thirty-two RP subjects self-completed an online survey about photopsias, approximately 1 to 2 months after ETDRS visual acuity (VA), Pelli-Robson contrast sensitivity (CS), and Goldmann visual field (VF) measures were obtained.
Results: The odds of noting photopsias only or mostly in areas of vision increased as vision was reduced across subjects, by 56% for every 0.1 logMAR VA (95% CI, 1.04-2.33; P = 0.03), 22% for every 0.1 logCS (95% CI, 1.02-1.46; P = 0.03), and 40% for every 1 unit logVF diameter (95% CI, 0.99-1.98; P = 0.06). The odds of noting photopias only in the periphery were reduced by 20% for every 0.1 logCS reduction (95% CI, 0.64-1.02; P = 0.066), and 18% for every 1 unit logVF diameter reduction (95% CI, 0.67-1.001; P = 0.051). For every 0.1 logMAR VA reduction, the odds of indicating that photopsias were located across a larger area over time were 30% greater (95% CI, 1.002-1.70; P = 0.048). The odds of being more aware of photopsias over time were increased as vision was reduced by 48% for every 0.1 logMAR VA (95% CI, 1.04-2.11; P = 0.03) and 18% for every 0.1 logCS (95% CI, 1.01-1.38; P = 0.04). The odds of reporting that photopsias interfere with vision were significantly greater when the photopsias occurred daily, more frequently, or across larger areas over time.
Conclusions: These cross-sectional data indicate that in later RP stages, photopsias located more centrally, over larger regions, in areas with vision, and/or observed more frequently may obstruct vision at times and are a potential hindrance for patients' functioning or when obtaining vision measures.