OSA Sleep Position May Influence Normal Tension Glaucoma

Studies have shown that in a side-sleeping posture, intraocular pressure tends to be higher in the lower-positioned eye, particularly in normal tension glaucoma. This position-influenced pressure change is believed to result from elevated episcleral venous pressure and excessive intraocular adipose tissue in obesity. Photo: Bruce Mars/Unsplash. Click image to enlarge.Obstructive sleep apnea is a well-recognized risk factor for glaucoma and normal tension glaucoma, in particular. Recent studies have investigated possible links between sleeping position and glaucoma. For instance, side sleeping is often reported as the favored sleep position among those with sleep apnea, as well as older individuals. To investigate the association between asymmetrical normal tension glaucoma and obstructive sleep apnea, researchers conducted a study to measure blood flow dynamics in the optic nerve head. Their findings, published recently in the Asia-Pacific Journal of Ophthalmology, showed reduced blood flow velocity in the downward-facing side-sleeping position.The cross-sectional study included 40 patients with normal tension glaucoma with obstructive sleep apnea (21 unilateral; 19 bilateral but asymmetrical) and 29 controls. All participants underwent eye exams and completed a sleeping position questionnaire. The researchers measured IOP and optic nerve head relative blood flow velocity (expressed as mean blur rate on laser speckle flowgraphy) after five minutes in supine and lateral decubitus positions.They found that while participants had comparable interocular characteristics, worse eyes had thinner central corneas and reduced mean blur rates for vascular area, tissue area and the entire area in side-sleeping positions. In worse eyes, mean blur rate for tissue area was less in the lower lateral decubitus position than in the upper lateral decubitus and supine positions.The researchers noted that for participants who slept with the worse eye lower, mean blur rates were less in the worse eyes in both lower and upper side-sleeping positions versus the fellow eye, but not in supine. For those who slept with the worse eye upper, mean blur rates for vascular and tissue area were less in the worse eyes only in the lower side-sleeping position, with no differences in other positions.“These individuals exhibit position-dependent inter-eye differences in optic nerve head blood flow velocity, with the worse eye demonstrating reduced mean blur rate for tissue area when it was in the lower (dependent) lateral decubitus position,” wrote the researchers. “Supine measurements, in contrast, showed little or no inter-eye difference.”They concluded that “These observations raise the possibility that a combination of OSA-related hypoxia, posture-related IOP changes, reduced optic nerve head mean blur rate and long-standing sleeping on the dependent side may contribute to asymmetric glaucomatous damage in susceptible eyes.”Click here for the source. Tun TA, Tan N YQ, Tan R KY, et al. Association of asymmetrical normal tension glaucoma, obstructive sleep apnea and side sleeping. Asia-Pacific Journal of Ophthalmology 2026. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.