Introduction There is some evidence that CPAP increases intraocular pressure (IOP) at night but this has not been examined in patients with glaucoma in whom IOP lowering is the mainstay of treatment.¹

Aim To assess the impact of CPAP on nocturnal IOP in patients with treated primary open-angle glaucoma (POAG) and in people with healthy eyes.

Methods All recruited participants were newly diagnosed with OSA and had indications for CPAP treatment. Nocturnal IOP was measured in both eyes in a supine position every 2 hours using a rebound tonometer (IcarePro). The measurements were obtained prior to starting CPAP and were repeated 4–6 weeks into the treatment. On the second night all measurements, apart from those taken at 10 pm, were obtained with participants using CPAP. Data were analysed using a mixed design ANOVA.

Results 14 POAG and 12 control participants were included. A mean apnoea-hypopnoea index (AHI) was 33.5±14.9 in the POAG group and 38.7±20.8 in the control group. A mean CPAP level was 10.8±2.9 cmH2O and 13±2.9 cmH2O, respectively. IOP measured with subjects using CPAP was significantly higher than at baseline with a mean increase of 2.7±2.2 mmHg (p=0.000) in all patients (figure 1). The difference in IOP increase between the groups was not statistically significant (2.2±2.2 mmHg [POAG] vs 3.2±2.2 mmHg [Control], p=0.27). In 50% of participants IOP increased by ≥5 mmHg at one or more time points. Among examined potential predictors of IOP increase (CPAP level, BMI, FVC, AHI,) only CPAP level was significantly correlated with IOP change (r=0.44, p=0.025).

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Abstract P55 Figure 1

Nocturnal IOP before and during CPAP therapy

Conclusions Our study confirms that CPAP raises nocturnal IOP. These findings may be particularly relevant to the management of people with POAG and co-existing OSA. Sleep specialist should inform ophthalmologists when commencing their patients on CPAP. Future studies should assess the long-term implications of using CPAP on glaucoma progression.

Reference

1. Kiekens S, Veva De G, Coeckelbergh T, et al. Continuous positive airway pressure therapy is associated with an increase in intraocular pressure in obstructive sleep apnea. Invest Ophthalmol Vis Sci 2008;49(3):934–40.