Topographic relationship between frequency-doubling technology threshold values

Abstract

Purpose: To study the topographic relationship of retinal sensitivity evaluated by frequency-doubling perimetry (FDT) in healthy subjects and patients with glaucoma.

Methods: Hundred and thirty-four eyes from 134 subjects (72 patients with glaucoma and 62 healthy controls) were prospectively and consecutively selected. Only one eye of each subject was randomly selected for evaluation. All subjects underwent a full ophthalmic examination and a reliable FDT (full-threshold C-20-5 algorithm). Pearson correlation coefficients between threshold values within the same hemifield were calculated. Maps of related points were plotted according to these correlation coefficients.

Results: In the control group, each FDT location strongly to moderately correlated with the other FDT locations in the same hemifield. In glaucoma subjects, only a few locations significantly correlated with other threshold values in the same hemifield. The strongest correlations were observed between neighbouring locations. The pairs of points with the strongest correlation corresponded to the inferior retinal regions. In general, perimetric maps showed the retinotopic distribution of ganglion cell axons in the retinal nerve fibre layer.

Conclusions: The statistical correlations between the FDT threshold values in the same visual hemifield objectively highlight the structure-function relationship determined by the anatomic distribution of retinal nervous tissue. This structure is altered in patients with glaucoma.