Diurnal variations in intraocular pressure,central corneal thickness,and macular and retinal nerve fiber layer thickness in diabetics and normal individuals

Purpose: to evaluate diurnal variations in intraocular pressure (iop),central corneal thickness (cct),and macular and retinal nerve fiber layer (rnfl) thickness in diabetic patients and normal individuals. methods: this study included 11 diabetic patients with macular edema and 11 healthy individuals. iop,cct,and macular and rnfl thickness were measured every 3 hours on a single day between 9 am and 6 pm. diurnal variations in iop,cct,total macular volume (tmv),central macular thickness (cmt),average macular thickness (amt),and rnfl thickness were measured. results: none of the parameters showed a significant absolute or relative change over the course of the day. however,the following non-significant changes were observed. in the control group,all parameters demonstrated the highest values at 9 am. the lowest iop,tmv and amt occurred at 12 pm; lowest cct and rnfl at 6 pm; and the lowest cmt at 3 pm. diabetic subjects had the highest values of rnfl,cmt and tmv at 9 am,and that for iop,cct and amt at 6 pm. the lowest rnfl and cmt values occurred at 6 pm; lowest iop at 12 pm; and the lowest cct,tmv and amt were observed at 3 pm. in the diabetic group,tmv,cmt,amt and cct were significantly higher and rnfl was significantly lower than the control group at all time points (all p- values < 0.05). conclusion: while there were slight decreases in iop,rnfl thickness and cmt during the day,these changes were not significant between 9 am and 6 pm and probably do not affect the interpretation of measurements. © 2016 journal of ophthalmic and vision research.