Mapping the thickness changes on retinal layers segmented by spectral-domain optical coherence tomography using the posterior pole program in glaucoma

Abstract

Abstract Objectives To evaluate changes in retinal layers of the macula (mRLs) using OCT posterior pole program (PPP) in primary open-angle glaucoma (POAG). Material and methods The study included 128 patients with POAG and 103 healthy controls who had PPP maps (macular grid 8 × 8) drawn by SD-OCT. Only one eye per patient was studied. The 9 mRLs were automatically segmented by prototype software, obtaining: a macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform + nuclear layer, photoreceptor layer, retinal pigment epithelium (RPE), outer retina and RPE + outer retina. Thickness values were obtained on 64 cells of the grid for each mRL, and mean thickness of superior and inferior hemispheres were calculated. Comparisons of mean thickness of these hemispheres and thickness of each cell between groups were determined. Differences in the cell by cell comparisons were represented quantitatively by heat maps for each mRL. Results Photoreceptors and RPE were found in POAG group when comparing thickness of hemispheres, thinning of mRNFL, GCL, IPL, and thickening of INL. Heat maps showed symmetrical thinning patters between superior and inferior hemispheres in inner retinal layers (except for INL) and asymmetrical thickening patters in outer retinal layers in GPAA group. Conclusions There are thickness changes in all mRLs in POAG, when studied by PPP. Thinning of inner layers (except for INL), and thickening of outer layers in POAG show different symmetry patterns in relation to horizontal meridian.