Comparison Between GDx VCC Parameter and Achromatic Perimetry in Glaucoma Patients

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Abstract

Purpose

To evaluate the correlation between polarimetry parameters and standard threshold perimetry indices.

Patient and Methods

One hundred and eight consecutive glaucomatous patients were recruited in this study. Glaucomatous patients were classified when an abnormal visual field and/or an abnormal optic nerve head were present. One eye was chosen randomly from all the subjects. All optic nerve heads were examined with the GDx variable corneal compensator (VCC) (Laser Diagnostic Technologies, Inc, San Diego, CA) and visual fields were assessed by Humphrey Perimeter, program 24-2, SITA standard (Humphrey Instrument, Inc, San Leandro, CA). GDx VCC parameters and visual field indices were considered. Correlation coefficient was used to compare the 2 sets of data. A linear regression model was also used to calculate the independent contribution of each GDx VCC parameter and to determine which parameter was the most predictive of visual field damage.

Results

The mean age (±standard deviation) was 61±10.3, the average of the mean deviation (MD) was −2.31±3.2 dB and the mean pattern standard deviation (PSD) was 3.32±2.83 dB. Significant (P<0.05) correlation was found between MD and the nerve fiber indicator (NFI) (r=−0.35), the superior average (r=0.28), the Temporal-Superior Nasal-Inferior Temporal average (r=0.24) and the inferior average (r=0.21). The linear regression model found NFI to be the predictor variable of MD. Significant (P<0.05) correlation was found between PSD and the NFI (r=0.39), the superior and the inferior average (r=0.30), and the Temporal-Superior Nasal-Inferior Temporal average (r=0.29). The linear regression model found NFI to be the predictor variable of PSD.

Conclusions

Some of the GDx VCC indices were significantly correlated to visual field indices in glaucomatous patients, but NFI was the best indicator of visual field damage.

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