Analyzing the impact of glaucoma on the macular architecture using spectral-domain optical coherence tomography

Using spectral domain optical coherence tomography (SD-OCT) the retina can be segmented automatically to visualize all retinal layers. In glaucoma chronically elevated intraocular pressure leads to a decline of retinal ganglion cells (RGC) which changes retinal architecture. The goal of these analyses was to gain insight into the changes induced by glaucoma within all macular layers using SD-OCT within a closely circumscribed glaucoma cohort.

SD-OCT measurements with automated retinal layer segmentation were performed in both eyes of primary open-angle glaucoma patients with a defined monocular absolute visual field scotoma in the central 10° of the visual field and in an age-matched healthy control group. Thickness of single retinal layers and entire retina were compared with special attention to the localization of the visual field scotoma in the glaucomatous eyes.

30 eyes of 15 glaucoma patients and 15 eyes of 15 healthy controls were included in this study. Statistical significant thickness differences were detected in the control group between superior and inferior retina for the retinal nerve fiber layer (RNFL), the outer plexiform layer (OPL) and the outer nuclear layer (ONL). In the glaucoma group thickness differences between worse and less affected eyes in the RNFL, the ganglion cell layer (GCL) and the inner plexiform layers (INL) were found. Comparison between healthy and diseased eyes revealed significant thickness differences in the RNFL, GCL, IPL and total retinal thickness but not the outer retinal layers.

Comparison between SD-OCT measurements of the macula between healthy and glaucomatous eyes in a closely circumscribed disease stage showed a pronounced disease impact on the inner but not the outer retina. These results provide evidence that GCL and IPL thickness seem to be good measures to discriminate between affected and unaffected eyes in testing for glaucoma.