Relative dispersion analysis enhances perimetric sensitivity

Comparison between relative dispersion analysis of high-pass resolution perimetry and standard threshold perimetry

PURPOSE

To evaluate the correlation of the dispersion index (DI) of relative dispersion analysis (RDA), a new high-pass resolution perimetry (HRP) index, with other HRP indices and those of the Humphrey standard threshold perimeter (STP) parameters.

METHODS

Sixty-eight eyes were randomly recruited. Thirty-one eyes were classified as glaucomatous (high intraocular pressure, abnormal visual field and/or optic disc) and 37 as ocular hypertensives (high intraocular pressure, normal visual field, normal optic disc). All the subjects were examined with Humphrey Perimeter, program 30-2, and HRP. The HRP data were also analysed with the RDA program. Statistical analysis was performed with Student's t-test, Pearson's r correlation coefficient, Mann-Whitney nonparametric test and Spearman correlation coefficient when appropriate.

RESULTS

Within the entire sample significant correlations were found between the RDA index (DI) and all the HRP indices (p < 0.001) and corrected pattern standard deviation (p < 0.01), pattern standard deviation (PSD) (p < 0.01), mean deviation (p < 0.05) and short-term fluctuation (p < 0.05) of STP. A stronger correlation was found in glaucomatous patients. In subjects with ocular hypertension DI was only weakly correlated with PSD, local deviation and form index. No difference in DI was found between glaucoma and ocular hypertension.

CONCLUSION

The DI of HRP has the theoretical capacity to detect localised inhomogeneity of retinal sensitivity, but at present our data do not support this hypothesis. Before any clinical applications of this index further studies are needed.