Purpose: To study the concordance of nictemeral IOP variations between fellow eyes in patients with treated and untreated OHT/POAG versus non-glaucoma patients. Also, we evaluate the symmetry or asymmetry level of mean, peak and IOP fluctuations between fellow eyes in glaucoma patients compared with normal controls.
Design: Cross-sectional study.
Methods: Applanation IOP and blood pressure were measured every 2 hours by one observer for 24 hours in 124 patients. The patients were classified: group 1--36 non-glaucoma patients (control group), group 2--32 patients with OHT and POAG without treatment, group 3--43 patients with OHT and POAG with a satisfactory diurnal therapeutic control of IOP (daytime IOP>21 mmHg) and group 4--13 patients with POAG with unsatisfactory control of IOP under maximal tolerated medication (daytime IOP>21 mmHg).
Results: The nictemeral curves of fellow eyes exhibited parallel profiles; according to the paired t-test there were no significant differences between fellow eyes throughout all measurement intervals. There is a high correlation of 24 h IOP between fellow eyes in all our study groups (r=0.8632, p<0.0001). There were no significant differences between fellow eyes in moment or value of peak IOP (paired t-test p=0.53). Comparing the mean absolute differences in IOP between fellow eyes throughout all 12 measurement points, the smallest differences between fellow eyes were found in groups 1 and 3 (0.85 mmHg, respectively 0.90 mmHg, p=0.47). The differences between fellow eyes were significantly greater in groups 2 and 4 (1.28 mmHg, respectively 2.6 mmHg, p<0.0001). The greatest probability of IOP differences to be in +/- 3 mmHg interval was found in normal patients (97.91%) and in patients with therapeutic control of IOP (97.26%). The greatest asymmetry of IOP was found in the group with therapeutically uncontrolled IOP (over 1/5 measurements were outside the +/- 3 mmHg interval).
Conclusions: The nictemeral variation of IOP in glaucoma patients were largely concordant between fellow eyes and the 24-hour IOP curves of fellow eyes exhibited parallel profiles. There were no significant differences between fellow eyes in mean, peak and IOP fluctuations. The asymmetry over +/- 3 mmHg between fellow eyes varied from 2.09% in normals to 20.53% in patients with therapeutically uncontrolled IOP.