Abstract
Purpose: :
To investigate the diurnal variations and interactions of the optic nerve head (ONH), intraocular pressure (IOP), central corneal thickness (CCT), and blood pressure in patients with newly–diagnosed, open–angle glaucoma.
Methods: :
After obtaining informed consent, each volunteer slept overnight at the Toronto Western Hospital sleep laboratory. ONH topography was measured using the Heidelberg Retina Tomograph–II (HRT–II). HRT–II, IOP, CCT and blood pressure measurements were taken in the evening before sleep, upon first awakening, and repeated at 20 and 40 minutes, and 1, 2, 3, and 4 hours after awakening.
Results: :
Nine patients with newly diagnosed, untreated, open–angle glaucoma (mean age 59.4 years, SD 14.8; range 42 to 85) and 14 control patients were recruited for the study. With respect to the optic disc topography, there was no overnight change in median cup volume, median rim volume, median maximum cup depth and median cup shape in either the glaucoma patients or controls (p > 0.05). There was an increase in IOP among the glaucoma patients within the first 40 minutes of awakening (p < 0.05). The CCT also was increased within the first 40 minutes of awakening (p < 0.05). When corrected for CCT, the increase in IOP in the glaucoma group was no longer significant.
Conclusions: :
In this group of study patients, the topography of the ONH did not significantly change overnight, unlike our previous findings in patients with obstructive sleep apnea. There was a statistically significant early morning increase in IOP and CCT when measured within the first 40 minutes of awakening in patients with newly–diagnosed glaucoma. This increase in IOP and CCT resolved within 1 hour. When the IOP was corrected for CCT this increase was no longer significant.
Keywords: optic disc • intraocular pressure • imaging/image analysis: clinical