Structure-Function Relationships between Macular Retinal Thickness using HRT3 and Standard Automated Perimetry

Abstract

Purpose: To investigate structure-function relationships between the macular 10-2 visual field(VF) assessed by standard automated perimetry(SAP) and the macular retinal thickness and volume measurements assessed by Heidelberg Retinal Tomograph 3(HRT3; Heidelberg Engineering, Heidelberg, German) in open-angle glaucoma(OAG) patients.

Methods: This cross-sectional study included 14 eyes of 14 OAG patients with central VF defects(within the central 10°) and 12 eyes of 12 normal subjects. All patients underwent macular imaging with HRT3(HRT3 Retinal module, v. 2.0.2) and VF testing(24-2 and 10-2, SITA-Standard Humphrey VF). The HRT3 nine-sector macular grid(1, 2.22, 3.45 mm diameter circles) was used for the assessment of the macular retinal thickness(MRT) and volume(MRV). The 10-2 VF was divided into 9 sectors approximately corresponding to the areas of the HRT3 macular grid. The macular VF mean sensitivity(MS) of each one of these sectors was determined. Correlations of global and sectoral MRT and MRV measurements, with global VF indices and corresponding regional VF MS(both in dB and 1/Lambert scales), were investigated using Spearman’s correlation coefficient.

Results: Global and sectoral macular VF MS were lower in glaucoma eyes in all sectors(P<0.001). Global and sectoral MRT and MRV measurements showed no statistically significant difference between the two groups, except the R3-inferior MRT(p=0,037) and R3-inferior MRV(p=0.030). The structure-function relationship between 10-2 VF and HRT3 macular parameters in the overall group of 26 eyes showed significant correlations only in two VF sectors. R2-inferior VF MS(dB) was correlated with R3-inferior MRV(rho=0.422; p=0.032). R3-inferior VF MS(dB) was correlated with R3-inferior MRT(rho=0.430; p=0.028) and MRV(rho=0.473; p=0.015). In glaucoma eyes, significant correlations were observed between R3-inferior VF MS, in dB and 1/L scale, and R3-temporal MRT(rho=0.563; p=0.036 and rho=0.559; p=0.038 respectively). In normal eyes, correlations between HRT3 sectoral macular thickness measurements and corresponding regional VF MS(both in dB and 1/Lambert scales), were not statistically significant, except between the R3-temporal VF MS and R3-superior MRT(rho=0.579; p=0.049).

Conclusions: Our results suggest that macular SAP generally shows little correlation to the macular retinal thickness and volume measurements determined by HRT3.

Keywords: 550 imaging/image analysis: clinical