Sector-Based Analysis of Frequency Doubling Technology Sensitivity and Optic Nerve Head Shape Parameters

Abstract

Purpose

To evaluate which Heidelberg Retina Tomograph (HRT) parameter is the best predictor of frequency doubling technology (FDT) sensitivity by using a sector based analysis between FDT and optic nerve head shape parameters such as cup shape measure (CSM) and rim area (RA), which have been shown to have the best correlation with FDT indices among all the HRT parameters.

Methods

One eye was randomly chosen from 100 patients with primary open angle glaucoma (abnormal visual field and/or abnormal optic nerve and untreated intraocular pressure above 21 mmHg). All the patients were examined with Humphrey field analyzer (HFA), program 24–2, SITA standard, FDT program C 20, and HRT. RA and CSM for the HRT analysis and mean deviation, pattern standard deviation, and the sensitivity of each tested point for the FDT test were considered in this study. All the parameters were calculated as both global and sector measurements. Findings were analyzed using Pearson's correlation coefficient and linear regression model.

Results

Significant (p<0.001) correlation was found between FDT indices and HRT RA and CSM. Significant (p<0.001) sector correlation was found between FDT sensitivity and RA and CSM, but when a linear regression model was applied, RA was the most predictive parameter of FDT. Temporal CSM was more strongly correlated to FDT fovea sensitivity than temporal RA. Furthermore, sector HRT parameters were better correlated to HFA than to FDT.

Conclusions

In this glaucomatous group, cup shape measure and RA were significantly correlated to FDT indices. RA was more predictive of FDT abnormality than CSM in all the considered sectors except in the temporal one. However, HFA was a stronger predictor of HRT parameters than FDT. (Eur J Ophthalmol 2007; 17: 223–9)