Abstract
Purpose:
OSAS is associated with hypoxia and hypercapnea which may cause a variety of changes to ocular structures. The purpose of this study was to look at CH, CCT and RNFL thickness in OSAS patients. Intraocular pressure (IOP), Humphrey visual field (HVF) global indices and optic disc parameters were also evaluated in these patients.<br /> <br />
Methods:
Patients who underwent overnight sleep studies (polysomnography) as part of the investigation of OSAS were recruited at the University Malaya Medical Centre, Kuala Lumpur. Best corrected visual acuity was measured, followed by CCT measurement using Lenstar optical biometry and then 24-2 SITA-Standard HVF assessment. CH was measured using a Reichert Ocular Response Analyzer, after which Goldmann applanation tonometry and gonioscopy were performed. Finally, the pupils were dilated and disc parameters including RNFL thicknesses and average cup: disc ratio were measured using Ocular Coherence Tomography. Only one eye was considered for each patient. Unpaired t-tests were employed for statistical analysis.
Results:
80 patients (49 males, 31 females) were included in this study. The Apnea Hypopnea Index divided them into normal, mild, moderate and severe OSAS. The normal and mild categories (47.5%) were then collectively called Group 1, and the moderate and severe categories (52.5%) were called Group 2. Patients in Group 2 had lower CH (9.8±1.5 vs 10.4±1.2 mmHg, p=0.049). CCT in Group 2 was higher (543.6±31.0 vs 535.3±24.6 µm) but this was not statistically significant (p=0.190). IOP in both groups were similar (15.4±2.7 vs 15.5±2.6 mmHg, p=0.944). Cup:disc ratios were significantly higher in Group 2 (0.56 ±0.11 vs 0.50±0.13, p=0.041). Average and quadrant RNFL thicknesses, as well as HVF global indices all showed no statistically significant differences between the 2 groups (p>0.05).
Conclusions:
Patients with moderate to severe OSAS have lower corneal hysteresis and increased cup:disc ratios as compared to normal to mild OSAS. As the two parameters can be associated with glaucoma, screening of patients with moderate to severe OSA is advisable.