Glaucoma Progression Detection at the Preperimetric Stage Through the Combination of Structural and Functional Information

Abstract

Purpose : The purpose of this study was to test the hypothesis that through the combination of longitudinal structural and functional information, early glaucoma progression can be detected at stages where visual field (VF) testing is still considered within normal limits.

Methods : Subjects were identified through the review of a longitudinal cohort of glaucoma suspects with full baseline VF testing and ≥5 visits with qualified OCT (Cirrus HD-OCT) and VF tests. Glaucomatous VF change was identified by the presence of clusters of three or more points corresponding with regions of statistically significant retinal nerve fiber layer (RNFL) thinning, both indicated by their respective guided progression analyses (GPA). Time of initial abnormality was defined as the visit where the earliest VF GPA changes occurred in these locations, consistent with later confirmed GPA change (three points worse on three consecutive tests) with corresponding OCT RNFL GPA thinning.

Results : 18 qualified subjects were identified with a mean baseline age of 61±15 years. At the time of initial abnormality their average VF mean deviation was -1.06±1.5dB and their average RNFL thickness was 77±9mm. The time interval between initial VF GPA change and confirmed GPA change was on average 42±22 months. Figure 1 shows an example of the testing for one subject over the course of 5 years.

Conclusions : The combination of structural and functional information enables glaucoma progression detection in certain eyes at a substantially earlier stage than possible with VF information alone, even at stages where the VF is still considered normal. The corresponding structural and functional information can allow clinicians to discern real glaucoma progression with a high degree of certainty, even in patients without abnormalities on conventional visual field testing.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Figure 1: OCT and visual field (VF) testing over the course of 5 years. Inferior retinal nerve fiber layer wedge defect progression is detected by the OCT guided progression analysis (GPA) and the area of progression gradually expands. VF testing remains classified as within normal limits throughout the course of follow up, even though a superior arcuate area of progression is confirmed by the VF GPA at the last visit. Combining structural and functional information allows progression detection 4 years earlier than detection by VF GPA analysis alone.