Diurnal variation of intraocular pressure, mean ocular perfusion pressure, optic nerve head topography and capillary blood flow in untreated early primary open angle glaucoma

Purpose. To investigate diurnal change and pattern of variation in intraocular pressure (IOP), blood pressure (SBP, DBP), optic nerve head (ONH) topography and capillary blood flow (BF) in untreated early primary open angle glaucoma (uPOAG) and healthy volunteers.; Methods. IOP, SBP, DBP and ONH topography (using the HRT II) were measured every hour and ONH BF was measured every two hours in 14 patients (age 56.3, SD 12, 7 men) with uPOAG and 14 normals (age 57.6, SD 9.9, 5 men), on a single day between 7 AM and 10 PM. The Mean Ocular Perfusion Pressure (MOPP) was calculated. Mixed effect linear models were used to analyse the repeated measures data in which both fixed and random effects were included.; Results. The uPOAG group had the higher IOP (p < 0.001) and tower MOPP (p = 0.025). There was a significant diurnal change in IOP, SBP, DBP, and MOPP in both groups (p < 0.001). The pattern of diurnal variation in IOP (p = 0.137), SBP (p = 0.569) and DBP (p = 0.937) was not significantly different between groups but was significantly different for MOPP (p = 0.040). Relative change in MOPP was larger in uPOAG (38% vs. 26%, p < 0.001) but was similar for IOP (42% vs. 41%, p = 0.786). There was a significant effect of DBP on IOP over the course of the day in uPOAG (p = 0.011) but not in normals (p = 0.733). Local Flow (LF) measured at the sector of most topography fluctuation (MTF) significantly changed in uPOAG (p = .006) but not in normals (p = 0.660). SBP had a significant effect on LF over the course of the day in uPOAG (p = 0.043). Temporal and temporal-inferior cup volume (CV), rim volume (RV) and cup shape measure (CSM) were significantly different between uPOAG and normals (p < 0.030). The temporal and temporal-inferior CV (p < 0.003) and reference height (RH) (p < 0.001) had a significant diurnal change in uPOAG and there was a significant association between RH and CV over the course of the day (p < 0.016). RH was significantly associated with change in MOPP in uPOAG (p = 0.002) but not in normals (p = 0.232). In normals, the RV in temporal, temporal-inferior and temporal-superior sectors significantly changed during the day (p < 0.016); Conclusion. Relative diurnal change in IOP was similar for both uPOAG and normals but MOPP showed significant differences. (Abstract shortened by UMI.)...