Obstructive sleep apnea may be an additional risk factor in the pathogenesis of retinal vein occlusion or a frequently associated condition that could be a triggering factor, researchers said in the December 2010 issue of Archives of Ophthalmology.
Dr. Agnès Glacet-Bernard of Intercommunal and Henri Mondor Hospitals/Assistance Publique des Hôpitaux de Paris, and her colleagues reviewed records of 63 consecutive patients with retinal vein occlusion (RVO) and chose 30 patients with two out of three risk factors for obstructive sleep apnea (OSA) – cardiovascular disease, snoring, and daytime sleepiness with an Epworth Sleepiness Scale score of higher than 10 – to receive further evaluation with respiratory polygraphy.
Twenty-three of the 30 patients (77%) selected for further evaluation had OSA, with a mean apnea-hypopnea index (AHI) of 21.3. Only one patient was previously diagnosed as having OSA. Ten patients required treatment with nasal continuous positive airway pressure with a mask during sleep, the researchers say, but because the treatment occurred several weeks or months after the onset of the RVO, it was impossible to determine whether treatment might play a beneficial role in visual outcome, the researchers say (Arch. Ophthalmol. 2010;128:1533-8).
Assuming the patients not evaluated did not have OSA, the estimated prevalence of OSA in this series of patients with RVO would be 37%. This lower estimate remains higher than the 2%-7% prevalence that is expected in the general population, according to the researchers.
Sleep apnea results in hemodynamic changes that contribute to a cascade of events leading to RVO. "These events may directly affect the retinal microcirculation, or they can act in concert with other predisposing conditions to RVO," the researchers say. "The immediate physiologic effects of OSA involve nocturnal hypoxemia, hypercapnia, and inspiratory efforts."
The study was limited in that researchers used historical control subjects and only evaluated a subset of patients with RVO who were at increased risk for OSA. Further studies are needed to determine if a causal relationship between OSA and RVO, and to determine the exact prevalence of OSA among patients with RVO, they stated.
"This study suggests that OSA, by acting on retinal microcirculation, could be an additional risk factor for the occurrence of RVO or, at least in older patients with a vascular profile, an associated condition that could play a determinant role in the development of RVO and that could act as a triggering factor," the researchers indicated.
"It is too early to know whether OSA treatment could modify the course of RVO or at least prevent its recurrence or the involvement of the second eye. Nevertheless, in clinical practice, it seems vital for the physician to be aware of this association because OSA treatment has demonstrated its efficacy in reducing the risk of cardiovascular and cerebrovascular disease in virtually any patient," they concluded.
The authors reported having no financial disclosures.