OCT

Pupils were dilated with topical 0.5% tropicamide and 0.5% phenylephrine (Mydrin-P®; Santen Pharmaceutical, Osaka, Japan) before the OCT examinations with a Cirrus high-definition OCT (HD-OCT) 4000 instrument (Carl Zeiss Meditec, Jena, Germany). The software automatically collected measurements of the peripapillary retinal nerve fiber layer (RNFL) with a diameter of 3.46 mm consisting of 256 A-scans centered on the optic disc. We obtained the average thickness of the circumpapillary RNFL (cpRNFL), then used the Macula Cube 200 × 200 and Ganglion Cell Analysis (GCA) programs to collect additional data in glaucoma patients as follows.

The macular cube scan generated one set of 200 horizontal B-scans, each composed of 200 A-scans centered on a 6- × 6-mm macular region. The built-in GCA algorithm (Cirrus H-OCT software, version 6.0) measured the thicknesses of the macular RNFL (mRNFL) and ganglion cell-inner plexiform layer (GCIPL) within a 6- × 6- × 2-mm cube in an elliptical annulus around the fovea. By using the GCA algorithm, the GCIPL thickness was calculated automatically as the distance from the outer boundary of the RNFL to the outer boundary of the inner plexiform layer (IPL) and stratified such as global and sectoral values (i.e., superonasal, superior, superotemporal, inferotemporal, inferior, and inferonasal sectors). All of the sectorial thickness obtained with OCT were shown based on the corresponding VF sectors. (Fig. 1a and b). We also measured the mRNFL thickness as the distance between the internal limiting membrane and the outer boundary of the RNFL and calculated the same six sectorial values. Ganglion cell complex (GCC) was measured as the value which added mRNFL with GCIPL and we also calculated the six sectorial values of GCC, similarly.

Association between optical coherence tomography (OCT) thickness and Humphrey Field Analyzer Central 10–2 program (HFA10–2). a The macular thickness is measured by OCT between two concentric circles of 2- and 6-mm diameters. b The findings of the HFA10–2 in right eye of glaucoma patient. Based on the retinal ganglion cell displacement [16], we classified the stimulus points on the HFA10–2 corresponding to the six sectors of the ganglion cell and inner plexiform layer (GCIPL) measurement ellipse into 6 groups (i.e., superior, superotemporal, inferotemporal, inferior, superonasal, and inferonasal sectors)

We only incorporated OCT images with a high quality of signal strength greater than 7/10 in the analysis.