Temporal Relation between Macular Ganglion Cell–Inner Plexiform Layer Loss and Peripapillary Retinal Nerve Fiber Layer Loss in Glaucoma

Abstract

To investigate the temporal relationship between inferior macular ganglion cell-inner plexiform layer (mGCIPL) loss and corresponding peripapillary retinal nerve fiber layer (pRNFL) defect on the optical coherence tomography (OCT) deviation map in glaucoma. Retrospective, observational study. A total of 151 patients with early-stage glaucoma (visual field [VF] mean deviation between-1.5 and-5.5 decibels [dB]). Spectral-domain OCT mGCIPL and pRNFL deviation maps were obtained for the baseline (from January 2012 to August 2012) and again for the follow-up (from January 2015 to August 2015). An integrated deviation map thereafter was merged by vascular landmark-guided superimposition of mGCIPL and pRNFL deviation maps onto RNFL imagery. On the basis of an earlier schematic model, the inferotemporal peripapillary area was divided into (1) the macular vulnerability zone (MVZ) and (2) the inferoinferior portion. Temporal sequence of inferior mGCIPL loss and corresponding pRNFL (i.e.,pRNFL in MVZ) defect on integrated deviation map. At baseline, 99 (65.6%) of the 151 eyes showed inferior mGCIPL loss. In addition, 112 eyes (74.2%) and 5 eyes (3.3%) showed inferoinferior pRNFL defect and pRNFL defect in the MVZ, respectively. At the 3-year follow-up, 112 (74.2%) of the eyes showed inferior mGCIPL loss, whereas 123 eyes (81.5%) and 25 eyes (16.6%) showed inferoinferior pRNFL defect and pRNFL defect in the MVZ, respectively. Ninety-four eyes initially showed inferior mGCIPL loss without pRNFL defect in the MVZ; among them, 19 (20.2%) subsequently showed defect during the 3-year follow-up interval. Meanwhile, among the 52 eyes without preexisting inferior mGCIPL loss, only 1 (1.9%; P < 0.001) developed a pRNFL defect in the MVZ during the 3-year follow-up interval. In eyes with early glaucoma, mGCIPL change is frequently detected before corresponding pRNFL change. This could be the result of a superior sensitivity of mGCIPL deviation map that allows detection of an abnormality in the mGCIPL thickness earlier. In this light, OCT pRNFL analysis alone likely would overlook macular damage. Macular OCT imaging should be included in the imaging algorithm for the serial observation of patients with glaucoma.