Macular Ganglion Cell Inner Plexiform Layer Thickness in Glaucomatous Eyes with Localized Retinal Nerve Fiber Layer Defects.

Chunwei Zhang,Akram Belghith,Na’Ama Hammel,Jeffrey M Liebmann,Christopher A Girkin,Robert N Weinreb,Ricardo Y Abe,Linda M Zangwill,Felipe A Medeiros,Andrew J Tatham

doi:10.1371/journal.pone.0160549

Abstract

PurposeTo investigate macular ganglion cell–inner plexiform layer (mGCIPL) thickness in glaucomatous eyes with visible localized retinal nerve fiber layer (RNFL) defects on stereophotographs.Methods112 healthy and 149 glaucomatous eyes from the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES) subjects had standard automated perimetry (SAP), optical coherence tomography (OCT) imaging of the macula and optic nerve head, and stereoscopic optic disc photography. Masked observers identified localized RNFL defects by grading of stereophotographs.Result47 eyes had visible localized RNFL defects on stereophotographs. Eyes with visible localized RNFL defects had significantly thinner mGCIPL thickness compared to healthy eyes (68.3 ± 11.4 μm versus 79.2 ± 6.6 μm respectively, P<0.001) and similar mGCIPL thickness to glaucomatous eyes without localized RNFL defects (68.6 ± 11.2 μm, P = 1.000). The average mGCIPL thickness in eyes with RNFL defects was 14% less than similarly aged healthy controls. For 29 eyes with a visible RNFL defect in just one hemiretina (superior or inferior) mGCIPL was thinnest in the same hemiretina in 26 eyes (90%). Eyes with inferior-temporal RNFL defects also had significantly thinner inferior-temporal mGCIPL (P<0.001) and inferior mGCIPL (P = 0.030) compared to glaucomatous eyes without a visible RNFL defect.ConclusionThe current study indicates that presence of a localized RNFL defect is likely to indicate significant macular damage, particularly in the region of the macular that topographically corresponds to the location of the RNFL defect.

Highlights

Glaucoma is characterized by loss of retinal ganglion cells (RGCs) and their axons that manifests clinically as structural changes to the optic nerve head (ONH) and circumpapillary retinal nerve fiber layer. [1,2] These changes are accompanied by a reduction in visual field sensitivity, which without adequate treatment, may progress to visual impairment and blindness. [3,4]Glaucomatous damage to the ONH and cpRNFL can be observed directly using biomicroscopy or recorded using optic disc stereophotographs
The current study indicates that presence of a localized RNFL defect is likely to indicate significant macular damage, in the region of the macular that topographically corresponds to the location of the RNFL defect
[10] The macular ganglion cell layer is of particular interest due to its importance for central vision and the high density of RGCs in this region. [11,12,13] previous studies have demonstrated the value of macular thickness measurements for glaucoma diagnosis using various parameters, including macular ganglion cell-inner plexiform layer thickness, which is the combination of the ganglion cell and inner plexiform layer. [14,15,16,17,18,19]

Summary

Introduction

Glaucoma is characterized by loss of retinal ganglion cells (RGCs) and their axons that manifests clinically as structural changes to the optic nerve head (ONH) and circumpapillary retinal nerve fiber layer (cpRNFL). [1,2] These changes are accompanied by a reduction in visual field sensitivity, which without adequate treatment, may progress to visual impairment and blindness. [3,4]Glaucomatous damage to the ONH and cpRNFL can be observed directly using biomicroscopy or recorded using optic disc stereophotographs. Glaucoma is characterized by loss of retinal ganglion cells (RGCs) and their axons that manifests clinically as structural changes to the optic nerve head (ONH) and circumpapillary retinal nerve fiber layer (cpRNFL). [7,8,9] imaging in glaucoma has traditionally focused on the ONH and cpRNFL, recent advances in OCT have provided the means to image the inner retina and obtain quantitative measurements of macular structures including the retinal ganglion cell layer–the location of retinal ganglion cell bodies. [22,23] As localized RNFL defects may be a consequence or cause of the loss of RGC axons, it is important to understand the topographic relationship between RNFL and mGCPIL thickness in eyes with localized RNFL damage. The superior RNFL maps to the temporal and temporal superior GCL, while the inferior RNFL generally maps to the inferior GCL. [10,24]

Methods

Results

Conclusion