Once patients cross an obstructive sleep apnea severity threshold, they become more at risk for developing significant diabetic eye diseases, according to a study.
Patients with no signs of obstructive sleep apnea (OSA) to moderate OSA were not at an increased risk for diabetic retinopathy (DR), proliferative diabetic retinopathy (PDR) or diabetic macular edema (DME). However, patients with severe OSA had a two to three times higher risk for developing the diabetic eye diseases, study co-author Albert Y. Wu, MD, PhD, FACS, of Stanford University School of Medicine, told Ocular Surgery News.
“In our analysis, we compared patients without OSA to all patients with OSA, then compared patients with mild, moderate and severe OSA. We found no significant association between DR and the presence of OSA, though we did not separately determine the difference in risk between patients without OSA and patients with severe OSA. In comparing patients with mild and moderate OSA, no significant difference in presence of DR or DME was found. These results, along with the increased risk of diabetic eye disease in patients with severe OSA, led us to suggest that there is an OSA severity threshold beyond which the manifestations of OSA are significant in diabetic eye disease,” Wu said.
Associations with DR
In the study cohort of 317 patients, 172 had severe OSA, 71 had moderate OSA, 53 had mild OSA and 21 had no OSA. After completing a univariate analysis, DR was found to have a direct association with severe OSA (P = .019). Researchers noted severe OSA was more prevalent in patients with PDR when compared with patients with mild nonproliferative diabetic retinopathy (NPDR) or patients without DR (P = .005).
Additionally, patients with PDR were significantly associated with severe OSA compared with patients with no DR (P = .024).
“OSA affects between 58% and 86% of patients with diabetes mellitus. OSA is thought to contribute to the development and progression of DR by increasing insulin resistance, elevating inflammatory marker levels and raising blood pressure. These OSA manifestations have been hypothesized to accelerate damage to retinal vasculature and increase the risk of DR in diabetic patients,” Wu said.
When researchers compared all NPDR with PDR, PDR was found to be significantly associated with severe OSA (P = .043), as well as DME (P = .001).
Treatment may help
Secondary sleep measures, such as sleep efficiency, mean event time, arousal index and periodic limb movement index, were obtained from polysomnography and were not significantly associated with DR or DME, according to the study.
“Studies have found that OSA treatment with continuous positive airway pressure can lower inflammatory marker levels, which may subsequently reduce the microvascular damage seen in DR patients with OSA. In light of our study’s findings, patients with DR may benefit from evaluation and treatment of OSA,” Wu said.
DR is the leading cause of visual loss in adults aged 20 to 74 years, and by identifying associated medical conditions and risk factors, researchers may be able to manage patients with DR, Wu said.
“As serious sequelae may result from either untreated DR or OSA, ophthalmologists should consider screening their DR patients for OSA using a screening tool such as the STOP-BANG questionnaire to detect mild, moderate and severe OSA, after which patients can undergo formal diagnostic polysomnography. Diagnosing and treating OSA in DR patients may help prevent the progression of DR, as well as avoid the serious cardiovascular consequences of OSA, which include hypertension, coronary artery disease, myocardial infarction and stroke,” he said.