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Editors Selection IGR 16-4
Basic Research: Daytime vs 24hr IOP monitoring
Comment by Kaweh Mansouri on:
26430 24-hour versus daytime intraocular pressure phasing in the management of patients with treated glaucoma, Moodie J; Wilde C; Rotchford AP et al., British Journal of Ophthalmology, 2010; 94: 999-1002
Moodie et al. (1141) assessed the value of daytime vs. 24-hour intraocular pressure (IOP) monitoring in patients with glaucoma. They conclude that 24-hour IOP monitoring offers little advantage over daytime phasing. The study has methodological issues that might have influenced the outcome. Most importantly, IOP measurements were taken throughout the day in the sitting position. Ideally, such an investigation should be carried out with measurements taken in the habitual body position. It has been hypothesized that postural change from sitting to supine produces a redistribution of body fluid with a probable increase of episcleral venous pressure and, possibly, the choroidal vascular volume. Liu et al.1,2 have shown repeatedly (and confirmed by others) that in a majority of glaucoma patients a significant elevation of IOP occurs during the nocturnal period when measured in the habitual body position. These observations have clinical significance. When Barkana et al.3 measured IOP over 24-hours, this led to a change of treatment in 36% of eyes that had their maximum IOP occur out - side office-hours.
Recently, trials of continuous IOP monitoring with a wireless ocular telemetry sensor have shown consistently higher nocturnal IOPs in glaucoma patients
Of note, nocturnal IOP values were available for only 54% of patients in this study, reducing sample size and introducing selection bias. Contrary to previous studies, they included a mixed cohort of glaucoma subtypes (25% of overnight patients had congenital, aphakic, or chronic narrow angle glaucoma). It is possible that glaucoma subtypes have different circadian IOP patterns, although this has not been studied yet and would be an important topic of future research. Clinicians and scientists equally recognize the need for better understanding of the dynamic nature of IOP. So far, no tool has been available to measure IOP during sleep in real-life conditions. With the introduction of newer technologies, ambulatory 24-hour IOP monitoring could become part of clinical practice. Recently, trials of continuous IOP monitoring with a wireless ocular telemetry sensor have shown consistently higher nocturnal IOPs in glaucoma patients.4
References
- Liu JH, Zhang X, Kripke DF, Weinreb RN. Twenty-four-hour intraocular pressure pattern associated with early glaucomatous changes. Invest Ophthalmol Vis Sci 2003;44(4):1586-90.
- Liu JH, Kripke DF, Twa MD, et al. Twenty-four-hour pattern of intraocular pressure in the aging population. Invest Ophthalmol Vis Sci 1999;40(12):2912-7.
- Barkana Y, Anis S, Liebmann J, et al. Clinical utility of intraocular pressure monitoring outside of normal office hours in patients with glaucoma. Arch Ophthalmol 2006;124(6):793-7.
- Mansouri K and Shaarawy T. Continuous Intraocular Pressure Monitoring With a Wireless Ocular Telemetry Sensor: Initial Clinical Experience in Patients With Open Angle Glaucoma. Br J Ophthalmol. In Press.
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