Relationship Between Nocturnal Intraocular Pressure Fluctuation and Hypoxia in Patients With Sleep Apnea Syndrome

Abstract

Purpose:: Several reports showed positive relationship between glaucoma and sleep apnea. This study was conducted to determine the relationship between nocturnal fluctuation of intraocular pressure (IOP) and hypoxia in sleep apnea syndrome (SAS) patients.

Methods:: Twenty-six consecutive patients were referred for polysomnographic evaluation of suspected SAS. Patients were admitted to the sleep lab at LSUHSC for overnight polysomnography. Pulse oximetry was monitored overnight. IOP was measured using Tonopen at 7-8 pm before the beginning of sleep test, 2-4 times during the course of the sleep study as soon as the patient wake up due to obstruction apnea, and at the end of their sleep study at 7 am in the following morning. All IOP checks were done while the patient was in supine position. Patients with normal sleep study or not able to check the pressures during the study were excluded

Results:: Data from twenty patients was included in the study. The IOP results in both eyes were compared and no statistically significant difference noted, so the right eye results from each patient were used for statistics. There was no association between IOP fluctuation and TIB hypoxia regardless of its severity; <90% (r =-0.175, P =0.51), <85% (r = -0.214, P = 0.41), or <80% ( r = -0.221, P = 0.41).There was no association between maximum IOP an TIB hypoxia; <90% (r = -0.2, P = 0.45), <85% (r = -0.219, P = 0.41), or <80% ( r = -0.216, P = 0.42). There was no correlation between lowest O2 saturation and IOP fluctuation, r = 0.133, P = 0.62 OD. Similar finding was noted in regards to the lowest O2 saturation and maximum measured IOP, r = 0.087, P = 0.74.

Main Outcome Measures:: Range of IOP fluctuation (the difference between the highest and the lowest reading), Respiratory Disturbance Index, and Time In Bed (TIB) hypoxia. Hypoxia was classified according to Oxygen (O₂ ) saturation <90%, <85%, and <80%. The correlation of the lowest O2 saturation to IOP fluctuation was also analyzed.

Conclusions:: There is no association between nocturnal variation in IOP or maximum IOP and hypoxia seen in sleep apnea syndrome.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • intraocular pressure • hypoxia