Choroidal thickness changes in obstructive sleep apnea syndrome: a systematic review and meta-analysis

Obstructive sleep apnea syndrome (OSAS) is a common chronic disorder associated with hypoxia and endothelial and vascular dysfunction. Many studies have analyzed choroidal thickness measurements in patients with different severities of OSAS versus normal subjects by optical coherence tomography (OCT), but the results have been inconsistent. Therefore, a meta-analysis was performed to evaluate the choroidal thickness changes in OSAS measured by OCT.

Pertinent studies were retrieved by a comprehensive search of PubMed, Embase, Web of Science, and the Cochrane Library from inception to August 2015. For continuous outcomes, the weighted mean difference (WMD) and 95 % confidence interval (CI) were calculated by using a random effects model.

Seven case-control studies were included in the final meta-analysis, containing a total of 784 eyes (558 in the OSAS group and 226 in normal controls). The results showed that subfoveal choroidal thickness (SFCT) was significantly reduced compared with normal controls, with pooled WMD -8.06 (95 % CI -15.72 to -0.41) for mild OSAS, -29.99 (95 % CI -52.40 to -7.58) for moderate OSAS, and -53.72 (95 % CI -88.95 to -18.48) for severe OSAS. Choroidal thickness at 1 mm temporal to the fovea and at 1 mm nasal to the fovea were also significantly lower than those in the normal controls (WMD = -28.94, 95 % CI -43.78 to -14.10 and WMD = -20.90, 95 % CI -36.62 to -5.18).

This meta-analysis suggests that choroidal thickness was reduced in OSAS. Considering the non-invasive nature of OCT, OCT could be a useful tool for grading the severity of OSAS.