Relationship between the macular ganglion cell complex thickness and standard automated perimetry in glaucoma

Abstract

Purpose: To assess the relationship between the macular thickness for the sum of the ganglion cell layer and inner plexiform layer (GCC) measured by spectral-domain optical coherence tomography (OCT) and white-on-white standard automated perimetry (SAP).

Methods: Fourty-five healthy controls and 37 glaucoma patients were imaged with Cirrus OCT (Carl Zeiss Meditec, Dublin, Ca). Glaucomatous eyes had intraocular pressure higher than 20 mmHg and abnormal standard automated perimetry (Humphrey Field Analyzer, Carl Zeiss Meditec; 24-2 SITA Standard strategy). Only one eye per participant was randomly included in the statistical analysis. Left eye data were converted to a right eye format. The peripapillary retinal nerve fiber layer (RNFL) thicknesses, the optic nerve head (ONH) parameters and the GCC measurements obtained with Cirrus OCT were included in the study. After checking for a normal distribution of the variables, Pearson correlations were calculated and compared between the OCT and the SAP parameters. The scatter diagrams and the regression lines were also plotted for the strongest correlations.

Results: Age and central corneal thickness did not differ significantly between the groups. Mean deviation of SAP was -6.86 ± 6.4 dB, in the glaucoma group. All OCT parameters were different between healthy and glaucoma patients except disc area and the RNFL thicknesses at the 3 and 9 clock hour positions. The control group had few mild correlations, while the glaucoma group showed moderate correlations between most OCT parameters and the visual field indices. In the whole population, the strongest correlation was observed between the temporal inferior GCC thickness and the pattern standard deviation (PSD) of SAP (-0.749, p<0.001). The strongest correlation for the RNFL parameters was found between the RNFL average thickness and the PSD of SAP (-0.677, p<0.001), while for the ONH parameters was found between the rim area and the PSD of SAP (-0.617, p<0.001). There were not significant differences between the best correlations of these parameters.

Conclusions: Moderate correlations were observed between the OCT parameters and the indices of SAP in glaucoma patients. The GCC parameters of Cirrus OCT had the strongest correlations with the visual field outcome. This relationship was linear.

Keywords: 550 imaging/image analysis: clinical • 531 ganglion cells • 758 visual fields