Correlation between the Thickness of the Macular Ganglion Cell Inner Plexiform Layer and Axial Length

Abstract

Objective: To investigate the thickness distribution of the macular ganglion cell inner plexiform layer (mGCIPL) in normal eyes using Cirrus HD OCT; to study the correlation between mGCIPL thickness and axial length, in order to discuss variations in the thickness pattern of the mGCIPL as axial length varies. Methods: This was a case series study. Patients referred to the ophthalmology clinic from September 2017 to April 2018 who met the inclusion criteria were enrolled. A total of 276 eyes of 170 subjects were selected. All subjects underwent complete ophthalmic examination, IOL Master measurements of axial length, and Cirrus HD OCT measurements of mGCIPL thickness to obtain 8 parameters, including the average thickness of 6 mGCIPL sectors (superotemporal, superior, superonasal, inferotemporal, inferior, inferonasal), the mean mGCIPL thickness of the elliptical annulus and minimum mGCIPL thickness. To study the distribution of mGCIPL, a correlation analysis between mGCIPL thickness and axial length was calculated by Spearman as well as a multivariate analysis of mGCIPL thickness using generalized estimating equations (GEE). Results: mGCIPL thickness of the 6 sectors of all the subjects was not identical (P superior>superotemporal≈inferotemporal≈inferonasal>inferior. In correlation analysis, 8 parameters had a negative correlation with axial length (r<0, P<0.001). In GEE, 8 parameters were influenced by axial length (β=-3.201, P<0.001) and age (β=-0.185, P<0.001). Conclusions: mGCIPL thickness distribation as follow: superonasal>superior>superotemporal≈inferotemporal≈inferonasal>inferior. mGCIPL thickness has a negative correlation with axial length. Axial length should be taken into account when using mGCIPL to diagnose glaucoma, especially in high myopic eyes. Key words: macular ganglion cell-inner plexiform layer; axial length; age; optical coherence tomography; glaucoma