Prediction of glaucomatous visual field progression: pointwise analysis

Abstract

Purpose: To evaluate whether pointwise regression analysis of serial measures of retinal sensitivity can predict future visual field (VF) loss.

Methods: Medical records of 158 patients with glaucomatous eyes with at least 6 years follow-up and 10 reliable VF exams were retrospectively analyzed. The entire follow-up period was divided into two, roughly corresponding to the first (early period) and second (late period) half of follow-up. Retinal sensitivity data obtained from the Swedish interactive threshold algorithm standard or full-threshold VF tests were analyzed, and linear and first-order exponential regression analyses of retinal sensitivity against time were performed to obtain the slope of regression analysis in each VF test location. Paired t tests were used to compare the slopes of the early and late period in each regression analysis.

Results: When assessed by linear regression analysis, inferior nasal location showed highest rate of change (-0.52 dB/year) in early period. Late period showed generally faster rate of progression compared to early period. Superior arcuate and superior and inferior nasal locations showed that early and late slopes did not show significant difference (p value, 0.19 ∼ 0.49). Central and edged locations showed significant difference between the two slopes (p value < 0.05). First-order exponential regression analysis showed similar result.

Discussion: Superior arcuate and superior and inferior nasal areas in VF had a consistent rate of change of retinal sensitivity, indicating that these locations may have the higher capability for prediction of future deterioration. These results suggest that location should be considered when predicting glaucomatous VF progression.

Keywords: Disease progression; GPA; glaucoma; prediction; visual field tests.

FIGURE 1

Mean of linear regression coefficients (dB/year), for early period (A), late period (B) and entire period (C) in each VF test location. p Values after Bonferroni correction from paired t test of linear regression coefficients comparing early with late period (D), and early with entire period (E), location scheme (F).

FIGURE 2

Mean of exponential regression coefficients (multiplied by 10 for better interpretability), for early period (A), late period (B) and entire period (C) in each VF test location. p Values after Bonferroni correction from paired t test of linear regression coefficients comparing early with late period (D), and early with entire period (E), location scheme (F).