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Elevated supine IOP often undetected in glaucoma management
Researchers reported that glaucoma patients experienced significantly higher supine intraocular pressure than sitting IOP, according to a study recently published in the British Journal of Ophthalmology.
The difference may provide insight into unexplained progressive glaucoma, Gautam and colleagues said.
Researchers conducted a prospective, observational cross-sectional study to assess diurnal variation and postural fluctuations of IOP in patients with various types of glaucoma.
The study included 18 participants with normal tension glaucoma (NTG), 19 participants with ocular hypertension (OHT), 19 participants with primary open angle glaucoma (POAG), 26 participants with optic discs suspicious for glaucoma and 20 normal participants. Researchers measured IOP at four times – 9 a.m., 4:30 p.m., 10 p.m. and 4:30 a.m. – using a portable Goldmann–Perkins applanation tonometer (Clement Clarke).
Results showed that at all times, in all groups, supine IOP was significantly higher than sitting IOP. Participants with POAG, OHT and NTG had significantly higher postural fluctuation at 4:30 a.m. Additionally, researchers reported that, in the group of NTG participants, the postural fluctuation at 9 a.m. was significantly correlated with the mean deviation of visual fields.
"An office postural fluctuation may be a good surrogate for diurnal variation so as to at least detect peak IOPs in the supine posture," the authors concluded. "The postural fluctuation measurement in such patients may at least be an indicator to which patients may need to be tested for a diurnal variation of IOP throughout the day." – by Chelsea Frajerman Pardes
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Intraocular pressure remains one of the few modifiable risk factors for glaucoma.
Patient IOP is usually measured in the sitting position during typical office hours. What happens to the IOP at night when patients are sleeping in the supine position is not as well known.
The purpose of this study was to evaluate postural fluctuations (PFs) and diurnal variation (DV) of IOP in patients with untreated glaucoma, glaucoma suspects and healthy volunteers and to evaluate any association with glaucomatous damage.
At all time points measured, the supine position IOP was significantly higher than the sitting IOP. The authors suggest that an early morning supine IOP measurement may reveal a peak IOP that maybe missed during routine office IOP measurements. This may provide additional information for those patients who have continued progression despite achieving target IOPs as measured during office visits.