AIM:To determine whether there was a significant relationship between eye iris color with axial length, intraocular pressure, retinal nerve fiber layer (RNFL) thickness, macular thickness and choroidal thickness.METHODS:A prospective cross-sectional study involving 92 eyes of 92 healthy volunteers.These were divided into dark colored-eye (DCE) and light-colored eye (LCE) groups according to iris color.The RNFL and macular thicknesses were analysed with standard optical coherence tomography (OCT) protocol while choroidal thickness was analysed with electronic data interchange (EDI) protocol in all subjects.Choroidal thickness was measured at the fovea, 1500 μm nasal and 1500 μm temporal to the fovea in a horizontal section.RESULTS:Of the 92 eyes included, 62 (67.4%) were dark-colored while 30 (32.6%) were light-colored.The mean age was 29.22±5.86y in the subjects with DCE and 28.86±6.50y in those with LCE.No significant difference was detected in mean age, axial length, macular thickness, choroidal thickness and intraocular pressure (IOP) between the groups (P>0.05).However, RNFL thicknesses varied depending on the quadrant measured, and were lower in both global and the nasal and temporal quadrants for individuals with LCE (P≤0.022).CONCLUSION:No significant differences were found in IOP, macular thickness and choroid thickness between individuals with DCE and LCE.Meanwhile, the RNFL thickness is lower.

AIM:To evaluate the potential posterior segment effects of topical application of brimonidine-purite 0.15％ through measurement of choroidal thickness (CT) in healthy eyes using enhanced depth imaging spectraldomain optical coherence tomography (EDI-SD-OCT).METHODS:Thirty-two eyes of 32 healthy subjects were included in this prospective,placebo controlled interventional clinical trial.They received one drop of topical preservative-free artificial tears as placebo for the first day and one drop of brimonidine-purite 0.15％ for the second day.Intraocular pressure,ocular perfusion pressure (OPP),and EDI-SD-OCT were performed at baseline,at 1,3 and 5h after the treatments.RESULTS:Compared to the measurements obtained at baseline,the CT measurements obtained after the topical application of brimonidine-purite 0.15％ significantly increased at the sub-fovea (P=0.001),at temporal 1500 μm to the fovea (P=0.003) and at nasal 1500 μm to the fovea (P=0.003).Choroidal thickness was unchanged in placebo group during the study (P ＞0.05).There was no significant reduction in the OPP in both groups (P ＞0.05).There were no adverse events during the study.CONCLUSIONS:Contrary to expectations,topical administration of brimonidine-purite 0.15％ resulted with thickening of sub-foveal,temporal and nasal CT.This might be related to altered auto-regulation mechanisms in choroidal vessels.