Corneal Endothelial Morphology and Thickness Alterations in Patients With Severe Obstructive Sleep Apnea–Hypopnea Syndrome

Abstract

Purpose: To investigate central endothelial cell density (ECD), morphology, and central corneal thickness (CCT) in patients newly diagnosed with severe obstructive sleep apnea–hypopnea syndrome (OSAHS) and to determine the correlation between these parameters and OSAHS severity. Methods: This prospective, comparative case series was conducted in a university ophthalmology clinic. In total, 51 patients recently diagnosed with severe OSAHS (apnea–hypopnea index above 30) and a paired, age and sex-matched control group of 44 healthy individuals were enrolled. After detailed ophthalmologic examination, specular microscopy measurement was performed for all participants. Central ECD, average cell area, coefficient of variation (CV) of cell area, hexagonal cell appearance ratio (% Hex), and CCT were compared between the groups. The Pearson correlation test was also used to assess the influence of the polysomnographic findings, that is, the proportion of each stage of sleep, apnea–hypopnea index, SpO2, mean and maximum duration of apneas, oxygen desaturation index, and arousal index on corneal endothelial morphometric parameters and CCT. Results: A total of 190 eyes were examined: 102 eyes of patients with severe OSAHS and 88 eyes of the control group. The mean ECD, CV, % Hex, and CCT values in the OSAHS group were 2439.25 ± 344.36 cells/mm2, 41.41 ± 11.62, 45.22 ± 7.06%, and 533.88 ± 40.53 μm, respectively. ECD and CCT did not significantly differ between the groups (P = 0.46, P = 0.55, respectively). CV value was significantly higher (P = 0.009), whereas the %Hex was significantly lower (P = 0.01) in the OSAHS group. We observed a significant negative correlation between CCT and REM sleep percentage (P = 0.005). Conclusions: Greater pleomorphism and polymegathism of corneal endothelium was found in patients with severe OSAHS when compared with healthy subjects. Low percentage of REM sleep, usually found in patients with OSAHS, may cause an increase in corneal thickness.

Effects of Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea–Hypopnea Syndrome on Corneal Morphological Characteristics

“…Corneal endothelial cells are known to be susceptible to oxidative stress, 19 and there are 2 studies 16,17 implying corneal endothelium alterations in patients with OSAHS, probably because of oxidative stress induced by chronic hypoxia. ECD values 16 and %Hex 17 have been found to decrease, whereas CV 17 has been found to increase in patients with untreated OSAHS. There are also a few studies 13,15,16 suggesting that CCT is significantly lower in patients with untreated OSAHS when compared with healthy individuals, possibly because of the hypoxia and hypercapnia induced in those patients.…”

“…There are few studies in the literature which have analyzed the corneal morphological [13][14][15][16][17] characteristics of patients with OSAHS, indicating that there is an insult to the corneal endothelium and corneal thickness, probably due to oxidative stress induced by chronic hypoxia. So far, no study has elucidated the therapeutic effectiveness of CPAP on the corneal morphometric variables.…”

Response to Letter to the Editor: Association of Metabolic Syndrome With Glaucoma and Ocular Hypertension in a Midwest United States Population

“…The relationship between OSA and CCT is controversial with some studies showing diminished CCT with OSA compared with controls [9][10][11] and other studies showing no difference. [12][13][14] Future multivariate analyses or prospective studies could determine whether OSA is a significant contributor to the relationships observed between IOP, CCT, and MetS.…”

“…Since IOP was no longer significant after adjusting for CCT, our data suggested the primary metric associated with MetS in patients with GON was CCT. The relationship between OSA and CCT is controversial with some studies showing diminished CCT with OSA compared with controls9–11 and other studies showing no difference 12–14. Future multivariate analyses or prospective studies could determine whether OSA is a significant contributor to the relationships observed between IOP, CCT, and MetS.…”

Ocular Complications of Obstructive Sleep Apnea

“…See et al conducted a nationwide population-based matched case–control study and found no significant association between KC and SA [ 108 ]. Topographic and biomechanical corneal variations (corneal volume, corneal elevation, and minimum radius) [ 109 ], as well as greater pleomorphism and polymegathism of the corneal endothelium [ 110 ], were found in severe OSA when compared to healthy subjects. The percentage of rapid eye movement sleep, which helped corneal oxygenation and usually decreased in patients with OSA, was also negatively correlated with central corneal thickness [ 110 ].…”