Purpose: Macular optical coherence tomography (OCT) analysis can be used for quantitative measures of optic nerve atrophy at a location far from the optic nerve head. This recently led to the finding of microcystic macular edema (MME), that is vacuolar inclusions in the macular inner nuclear layer, in some glaucoma patients. The involvement of individual retinal layers is yet unclear in glaucoma. In this study we systematically investigated glaucoma-induced changes in macular layers to evaluate whether glaucoma-associated damage extends beyond the macular ganglion cell layer.
Patients and methods: We included 218 consecutive patients and 282 eyes with confirmed primary open-angle glaucoma or pseudoexfoliation glaucoma, and macular OCT in a cross-sectional observational study. Eyes were screened for presence of MME. Thickness of individual retinal layers was determined using a semiautomatic segmentation algorithm. Peripapillary nerve fiber layer thickness and mean defect in visual field testing were extracted from OCT and medical records, respectively. Results were compared with a small group of eyes with no apparent glaucoma.
Results: We found MME in 5 eyes from 5 primary open-angle glaucoma patients and 3 eyes of 3 pseudoexfoliation glaucoma patients (2.8%). MME was confined to the inner nuclear layer in a perifoveal ring and was associated with thinning of the ganglion cell layer and thickening of the macular inner nuclear layer. Glaucoma eyes without MME showed a significant inverse correlation of inner nuclear layer thickness with glaucoma severity.
Conclusions: Glaucomatous damage leads to a gradual thickening of the inner nuclear layer, which leads to MME in more severe glaucoma cases. These changes, along with nerve fiber loss and ganglion cell loss, may be summarized as glaucoma-associated retrograde maculopathy.