The relationship between central visual field sensitivity and macular ganglion cell/inner plexiform layer thickness in glaucoma

Aims To explore the correlation of local macular ganglion cell/inner plexiform layer (GC/IPL) thickness measurements with sensitivity at individual test locations on the central 10-2 visual fields (VFs) in patients with glaucoma. Methods One hundred thirty-seven eyes of 125 patients with spectral domain optical coherence tomography (OCT) and 10-2 VFs were included. The exported thickness matrices (200x200) of GC/IPL measurements were centred on the fovea. Total deviation values at each test location were correlated with the 20 000 GC/IPL thickness measurements in the corresponding inferior or superior hemiretina, and areas of highest correlation were plotted. Macular structure-function relationships were also examined between six wedge-shaped GC/IPL sectors and the corresponding VF clusters. A multivariate model was built to identify the 10-2 VF test locations associated with each GC/IPL sector thickness. Results Average mean deviation on 10-2 VFs was -9.2 +/- 6.1 dB. The 10-2 VF test points demonstrated correlations with GC/IPL thickness in localised arcuate patterns mostly limited within the central 4.8x4.0 mm measurement ellipse (rho=0.43-0.74, p<0.05 for all). Twenty-one test points of the 10-2 VF were the best predictors of sectoral GC/IPL thickness. Sectoral VF-OCT correlations were high (rho=0.53-0.66, p<0.001) and did not significantly change after adjusting for retinal GC displacement (p>0.05). Conclusions Macular OCT/VF relationships have localised arcuate characteristics in the central region of the macula. Given the overlapping nature of structure-function relationships, a smaller number of VF test locations may be used to summarise macular functional damage.