Visual Field Index appears useful for determining stability but not progression

This study evaluated the capacity of the Visual Field Index (VFI) to provide information on perimetric glaucomatous progression. The authors conclude that VFI may have greater utility for determining stability rather than for detecting glaucomatous progression.

The study included 39 consecutive patients (51 eyes) with open-angle glaucoma with a minimum of six reliable visual fields and two years of follow-up. Four masked glaucoma experts from four different institutions subjectively assessed perimetric progression, classifying it as definite progression, suspected progression or no progression. These results were compared with Glaucoma Progression Analysis (GPA) II and VFI linear regression analysis, where progression was defined as a negative slope with significance of less than five percent.

The mean number of visual fields assessed was 7.8 per eye. Mean follow-up was 63.7 months. The mean VFI linear regression slope showed an overall statistically significant difference (P < 0.001, analysis of variance) for each category of progression.

The authors found that the mean VFI regression slope among eyes without perimetric progression showed a statistically significant difference compared with those considered to have suspected/possible or definite/likely progression. VFI analysis and GPA II both had similarly high specificity (0.93 and 0.90, respectively) but relatively low sensitivity (0.45 and 0.41, respectively) when compared with expert consensus opinion.

The authors conclude that VFI and GPA II may play important roles in providing reassurance to undecided clinicians that visual field progression does not seem to have occurred.