Evaluation of ocular changes and meibomian gland dysfunction with meibography in patients with obstructive sleep apnea syndrome

PURPOSE: Recently, the prevalence of obstructive sleep apnea syndrome (OSAS) is increasing as obesity is seen more frequently. Pathophysiological mechanisms, such as intermittent hypoxia, cyclic desaturations and increased level of catecholamines, underlying OSAS has also an impact on oculovascular health. In this study, our aim is to investigate tear film and ocular surface abnormalities, meibomian gland dysfunction (MGD), along with corneal topographical and biomechanical properties, corneal endothelial cell morphology and to evaluate retinal nerve fiber layer (RNFL) and subfoveal choroidal thickness (SFCT) in OSAS patients, as compared with controls. MATERIALS and METHODS: Fifteen patients with simple snoring and 57 patients with OSAS (mild, moderate and severe OSAS; 9, 12 and 36 patients, respectively) according to polysomongraphic and/or polygraphic evaluation, who admitted to EUTF Department of Pulmonology, Sleep Laboratory from March 2016 to May 2017, were enrolled. Complete ophthalmological examination along with tear film tests (Scihrmer and t-BUT) were investigated. Corneal topographical and biomechanical properties, measurements of endothelial cell morphology, RNFL and SFCT were determined. MGD was evaluated with meibography. For statistical analysis, datas of simple snoring & mild OSAS (Group 1), moderate OSAS (Group 2) and severe OSAS (Group 3) were compared. RESULTS: The mean age of the patients was 47.9±10.5 (27-69), 51.5±12.9 (26-69) and 50.8±8.3 (35-68) in Group 1 (Male to Female ratio (M:F)=13/11), Group 2 (M:F=11/1) and Group 3 (M:F=28/8), respectively. Anterior and vertical distraction distance were significantly higher in patients with severe OSAS (p<0.05, Kruskal Wallis test). As severity of OSAS increases, upper (0.8±0.9 (0-3), 1.1±1.6 (0-4) and 1.8±1.9 (0-8) in Group 1, 2 and 3, respectively) and total (1.1±2.2 (0-6), 1.8± 2.2(0-6) and 2.8±2.3 (0-11) in Group 1, 2 and 3, respectively) meiboscores increase and t-BUT (11.5±5.1 (4-24), 10.1±5.8 (4-18) and 7.1±6.5 (2-17)in Group 1, 2 and 3, respectively) decreases significantly (p<0.05, Kruskal Wallis test). t-BUT was in moderate negative correlation with upper and total meiboscore (Spearman's rho (r)=-0.425, p<0.001 and r=-0.352, p=0.002). Corneal topographical and biomechanical properties, measurements of endothelial cell morphology and SFCT did not differ significantly (p>0.05, Kruskal Wallis test). In terms of RNFL, inferonasal RNFL thickness (129.23.6 (80.0-168.5), 116.4±25.3 (71.5-167.5) and 102.9±18.9 (63.5-144.0) in Group 1, 2 and 3, respectively) was significantly lower in severe OSAS, while other quadrants showed no difference. CONCLUSION: In patients with OSAS, MGD is present and correlated with the severity of the disease. While there is no significant difference between groups, in terms of corneal topographical and biomechanical properties, corneal endothelial cell features and SFCT; significant decrement in inferonasal RNFL thickness was determined, as the OSAS severity increased. Key words: Obstructive sleep apnea syndrome, OSAS, non-contact meibography, meibom gland dysfunction, dry eye