Wide-Field En Face Swept-Source Optical Coherence Tomography Features of Extrafoveal Retinoschisis in Highly Myopic Eyes

PURPOSE. To evaluate the features of extrafoveal retinoschisis (EFRS) in highly myopic eyes detected by swept-source optical coherence tomography (SS-OCT). METHODS. In this retrospective case series, 89 eyes of 65 patients with high myopia and coexisting EFRS were included. The participants underwent a comprehensive ophthalmologic examination, including visual acuity, ocular biometry, refraction, and perimetry. Threedimensional wide-field scans were obtained with SS-OCT, and en face images were reconstructed with custom software. En face OCT features of EFRS were determined by two ophthalmologists masked to clinical characteristics. The associations of EFRS subtypes with ocular biometry and other OCT changes were evaluated as well. RESULTS. In wide-field SS-OCT scans, EFRS was classified into three different types, the inner limiting membrane (ILM) detachment and inner and outer EFRS, according to the specific layer of the splitting. All these three types were most frequently distributed in the inferotemporal quadrant (71.2% for ILM detachment, 59.5% for inner EFRS, and 75.0% for outer EFRS). Inner limiting membrane detachment and inner EFRS were often adjacent to peripapillary atrophy. Outer EFRS tends to coexist with inner EFRS, as we did not observe any case with standalone outer EFRS or with coexisting with ILM detachment. Eyes with all three types combined had the longest axial length (29.1 +/- 1.26 mm, P = 0.003) and the greatest refractive error (-13.0 6 2.86 diopters [D], P = 0.014). The incidence of retinal microfolds and breaks among subgroups was significantly different (P = 0.012 and 0.003, respectively). Staphyloma was associated with outer EFRS (30.6% with versus 7.6% without outer EFRS). CONCLUSIONS. Wide-field SS-OCT reveals the spatial distribution of retinoschisis outside the fovea, and associations with retinal vessels and other retinal landmark structures. Further observations on the longitudinal changes and functional damage would help lead to a better understanding of its mechanism and prognosis.