EDN1 and retinitis pigmentosa 1: Furthermore, Spearman's correlation test highlighted that the increase of ET-1 plasma levels in RP was related with the decrease of choroidal thickness (r = −0.702; P < 0.023; Figure 2) and the increase of intraocular inflammation, represented by aqueous flare (r = 0.580; P < 0.007; Figure 3), whereas no statistically significant correlation between aqueous flare and choroidal thickness (r = −0.308; P = 0.124) was reported.