Incidence of Normal Tension Glaucoma Among Chinese Patients with Treatment Naïve Obstructive Sleep Apnea Syndrome

Abstract

Purpose To investigate the one-year incidence and potential risk factors for normal tension glaucoma (NTG) in Chinese patients with newly diagnosed obstructive sleep apnea syndrome (OSAS). Methods This is a prospective cohort study conducted between 1st of July 2015 – 30th of June 2017. 220 consecutive subjects, who were referred to the respiratory clinic at Queen Mary Hospital for suspected OSAS, were recruited. Subjects with a pre-existing diagnosis of glaucoma or history of OSAS treatment were excluded from analysis. Subjects underwent polysomnography (PSG), using AHI ≥ 5 as the diagnostic OSAS. The subjects further underwent glaucoma workup at Grantham Hospital, including slit lamp examination, gonioscopy, intraocular pressure measurement, and at least two Humphrey Visual Field 24-2 and Ocular Coherence Tomography (OCT) nerve fiber layer assessments four months apart from each other. Anderson’s criteria were used for normal tension glaucoma diagnosis. Results 196 Chinese subjects consented for the study. On follow-up, 7 subjects were further excluded as they did not complete at least two ophthalmic assessments. 64.5% of subjects were male, with a mean age of 54.2 ± 9.89. The overall one-year incidence of normal tension glaucoma in this cohort was 6.34%. Subjects with more severe OSAS had higher incidence of NTG. There were no significant correlations between AHI score and glaucoma parameters. Conclusions Patients with OSAS are at increased risk of NTG. Increased OSAS severity, as measured by AHI, is a marker for higher risk of NTG. It is worthwhile to investigate the cost-effectiveness of glaucoma screening in this cohort.