Examination of corneal topographical changes in patients with obstructive sleep apnea syndrome

IŞIK I, Examination of corneal topographical changes in patients with obstructive sleep apnea syndrome, Bulent Ecevit University Ophthalmology Department, Zonguldak 2018 Purpose: To evaluate the corneal topographic changes and anterior segment parameters in patients with obstructive sleep apnea syndrome (OSAS) and also to determine relationship between these parameters and severity of the disease. Material and Methods: This prospective- comparative and randomized study was conducted between September 2016 and January 2018 at Bulent Ecevit University Health Practice and Research Center. The patient group was randomly selected from patients diagnosed with OSAS in Bulent Ecevit University Health Practice and Research Center Sleep Disorder Clinic. The control group was selected from healthy volunteers who applied to the outpatient clinic for eye diseases. One hundred and thirteen eyes of 60 patients with OSAS and 59 eyes of 30 healthy volunteers (group 0) were included in the study. The OSAS group was divided into 3 subgroups according to apnea hypopnea indexes as mild stage (group 1), moderate stage (group 2) and severe stage (group 3). All patients underwent complete ophthalmologic examination. Pupil diameter, minimum corneal thickness, apical corneal thickness, central corneal thickness, aqueous depth, aqueous volume, anterior chamber angle, horizontal anterior chamber diameter, corneal volume, simulated K values, keratometric values of the anterior and posterior cornea at 3 mm, RMS / A values, symmetry indices, keratoconus- anterior and posterior vertex heights and presence of keratoconus were compared using the combined Scheimpflug-Placido corneal tomography (SIRIUS 3D Rotating Scheimpflug Camera & Topography System V.3.2). Results: There was no difference between groups in terms of age and gender (p=0.946, p=0.966, respectively). Systemic hypertension rate and body mass index value wer respectively). Type 2 Diabetes Mellitus rates were significantly higher in the moderate and severe OSAS groups than other groups (p = 0.003). There was no significant difference in terms of pupil diameter, simulated K values, keratometric values of the anterior and posterior cornea at 3 mm, RMS / A values, symmetry indices, keratoconus- anterior and posterior vertex heights and presence of keratoconus between all OSAS groups and control group. Minimum corneal thickness value was found to be 532 (471-591) μm, 540 (470-604) μm, 558.5 (502-613) μm, and 534 (456-605) μm in the control and OSAS groups respectively and was significantly higher in the moderate OSAS group (p<0.001). Central corneal thickness value was 536 (470-600) μm, 544 (480-610) μm, 560 (400-620) μm and 538 (460-610) μm in the control and OSAS groups respectively and was significantly higher in the moderate OSAS group (p <0.001). There was no difference between groups in terms of apex thickness. Corneal volume was found to be 55.8 (51.30-65.80) mm3 57.7 (51.6-63.80) mm3 58.55 (54.0-67.0) mm3 and 56.3 (51.2-62.2) mm3 according to the order of the group and was significantly higher in the moderate OSAS group (p <0.001). Aqueous depth, aqueous volume, anterior chamber angle and horizontal anterior chamber diameter were significantly higher in the severe OSAS group (p = 0.001, p = 0.005, p <0.001, p = 0.007, respectively). In univariate analysis, the effect of type 2 DM on the parameters that differed significantly between groups was assessed and statistically significant. Thus, the analysis was repeated by removing the cases with Type 2 DM from the moderate and severe OSAS groups. In the second analysis, only the aqueous depth, aqueous volume and anterior chamber angle parameters were found to be significantly higher in the OSAS group (p = 0.005, p = 0.043, p <0.001, respectively), but there was no difference between the two groups in keratometric values and parameters related to corneal thickness > 0.05). Floppy eyelid syndrome was not detected in any case. Easy lid eversion rate was significantly higher in the moderate and severe OSAS groups than in the control group (rates: %6.8 ; %5.1 ; %28.9 ; %30.6, p = 0.001). Conclusion: Obstructive sleep apnea syndrome is also part of the metabolic syndrome and diabetes mellitus is detected at high rates in these cases. In our study, the corneal parameters were found to differ between the control group and the OSAS groups in the analysis of containing the patients with diabetes, however the relevant parameters were similar in the next analysis which excluding the diabetic cases. In OSAS patients without diabetes mellitus only differences in anterior chamber parameters were detected. According to the results of this study, no evidence of keratoconus was found in corneal parameters in OSAS cases. Key words : Obstructive sleep apnea sydrome, Corneal topography, Scheimpflug imaging