This study was a retrospective observational case series and was approved by the Research Ethics Committee of the Graduate School of Medicine and Faculty of Medicine at The University of Tokyo. Written informed consent was given by all participants and our study was conducted in accordance with the tenets of the Declaration of Helsinki.
Twenty-three eyes of 23 patients (18 male, 5 female) with chronic CSC were enrolled in the current study. The mean age of participants was 49.8 ± 10.7 years (mean ± standard deviation: SD). All patients underwent comprehensive ophthalmic examinations, including refractive error, best-corrected visual acuity (BCVA), intraocular pressure, anterior segment examination, and fundus biomicroscopy with pupil dilation. Patients were diagnosed based on OCT, fluorescein angiography (FA) and Indocyanine green angiography (ICGA). Chronic CSC was defined as those with CSC lasting more than 3 months. At the 1st measurement, all enrolled eyes demonstrated subretinal fluid (SRD) within central 12 degrees which decreased at the 2nd examination. The exclusion criteria were as follow: (1) a history of other retinal disorders; (2) a history of laser photocoagulation or photodynamic therapy; (3) the presence of high myopia (-6.0 diopter or greater)
VF measurement was carried out using the MP-3 microperimetry. The MP-3 microperimeter test is based on the 4–2 full threshold strategy using the Goldmann III stimulus size, as previously described. [13,17] The 25 measurement points were located within 12 degrees of the macular area as shown in Fig.1. All patients underwent VF measurement both at the 1st and 2nd measurements.
Spectral domain (SD) OCT images were obtained using the Spectralis OCT (Heidelberg Engineering, Germany). All OCT images consisted of line scans (horizontal and vertical B-scans), raster scans, and topographic mapping. The raster scan was performed using 25 B-scans (768 A-scans per B-scan) in a 30×20-degree area. OCT measurements were also performed both at the 1st and 2nd measurements in each eye. Using OCT images, we measured total retinal thickness (RT), retinal nerve fiber layer + ganglion cell layer (RNFL+GCL), inner nuclear layer (INL), outer nuclear layer (ONL), and SRDH at the 25 locations corresponding to 25 measurement points with MP-3. RT was defined as the distance between the internal limiting membrane and the RPE. SRDH was defined as the distance between ellipsoid zone (EZ) and RPE. These data were collected independently by two examiners. If the difference was large between two examiners, a panel discussion was held to draw a conclusion.
LogaMAR VA and mean retinal sensitivity were compared between the 1st and 2nd examinations (VA1 and VA2, mRS1 and mRS2). Retinal sensitivities, thicknesses (RT, RNFL+GCL, INL, and ONL), and also SRDH were compared between the 1st and 2nd examinations (RS1 and RS2, RT1 and RT2, RNFL+GCL1 and RNFL+GCL2, INL1 and INL2, ONL1 and ONL2, SRDH1 and SRDH2), at 25 measurement points. Among 6 variables (age, RNFL+GCL1, INL1, ONL1, SRDH1 and the improvement in SRDH: dSRDH), the variables associated with the retinal sensitivity at the 2nd examination were identified, using the corrected Akaike Imformation Criterion (AICc) model selection; the optimal model was selected from 26 patterns.  The AICc is a well-known statistical measure with which optimal variables can be determined without having an over-fit problem, unlike the coefficient of determination.  All statistical analyses were performed using the statistical programming language ‘R’ (R version 3.1.3; The Foundation for Statistical Computing, Vienna, Austria).