Reproducibility of the Mean, Fluctuation, and IOP Peak in the Diurnal Tension Curve

Purpose: To verify the reproducibility of the mean, peak, and fluctuation of intraocular pressure (IOP) observed during modified diurnal tension curves (mDTC) performed on ocular hypertensive and primary open-angle glaucoma patients.Methods: Prospective analysis of 88 eyes from 88 ocular hypertensive and primary open-angle glaucoma patients subjected to 2 consecutive mDTCs (IOP measurements obtained at 8:00 am, 11:00 am, 2:00 pm, and 4:00 pm) on 2 consecutive days. Mean IOP was calculated as the average of all IOP measurements obtained during each mDTC. Peak and minimum IOP levels were considered as the highest and lowest IOP level during each mDTC, respectively. IOP fluctuation was calculated using 2 different approaches: the difference between IOP peak and minimum IOP detected during each mDTC and as the SD of all mDTC measurements. Reproducibility was assessed using the intraclass correlation coefficient (ICC).Results: IOP fluctuation between 2 days in the modified diurnal curve, calculated as the difference between peak IOP and minimum IOP and as the SD of all mDTC measurements, was less reproducible than the mean IOP and peak IOP (ICC values 0.60, 0.62, 0.91, and 0.85, respectively; all ICC values, P<0.001).Conclusions: Mean IOP and peak IOP observed during the mDTC had good reproducibility, whereas the reproducibility of IOP fluctuation was only fair.