Abstract
Purpose: :
To study the 24-hour pattern of habitual ocular perfusion pressure (OPP) in a group of untreated glaucoma patients housed in a sleep laboratory.
Methods: :
Thirty five untreated glaucoma patients (ages 45-78 years) were entrained to a 16-hour wake and 8-hour sleep cycle for a week. At the end of entrainment, habitual blood pressure (BP) and intraocular pressure (IOP) in both eyes were measured every 2 hours in a sleep laboratory. During the diurnal/wake period, BP and IOP were measured after 5 minutes in the sitting position. During the nocturnal/sleep period, BP and IOP were measured in supine posture. Mean BP and average IOP of both eyes in the diurnal period and in the nocturnal period were calculated. Diurnal and nocturnal OPP in different body positions were calculated based on the mean BP and IOP, adjusted for the height of the eye over the heart. Data of sitting and supine BP and IOP obtained from an age-matched group of 16 healthy individuals (ages 47-74 years) after similar wake-sleep entrainment and under the same laboratory conditions were used for comparison.
Results: :
There was an increase of habitual OPP from the diurnal period to the nocturnal period in the group of untreated glaucoma patients (P < 0.01; Paired t-test). Mean diurnal sitting OPP and mean nocturnal supine OPP in the glaucoma patients were significantly less than those in the healthy individuals (P < 0.01; Student’s t-test). The nocturnal increase of OPP from the diurnal value in the group of glaucoma patients was smaller than that in the group of healthy individuals (P < 0.05).
Conclusions: :
The habitual OPP was higher during the nocturnal period than during the diurnal period in this group of untreated glaucoma patients. Both diurnal and nocturnal OPP in these glaucoma patients were less than the related pressures in the age-matched healthy individuals.
Keywords: intraocular pressure • blood supply • circadian rhythms