Abstract
Purpose: :
To determine if glaucoma patients with optic disc change with scanning laser tomography have earlier and higher rates of subsequent visual field progression compared to those with stable discs.
Methods: :
Disc and field examinations, using the Heidelberg Retina Tomograph (HRT) and standard automated perimetry (SAP), were performed every 6 months in 81 open-angle glaucoma patients followed for a median (IQR) of 11.0 (8.0, 12.0) years in a prospective study. Two initial follow-up periods: (i) 3 years (protocol A) and (ii) half of the follow-up (protocol B) were used to determine if disc change had occurred with liberal (L), moderate (M) and conservative (C) Topographical Change Analysis (TCA) criteria (Chauhan et al, IOVS, in press). The remainder of the follow-up was then used to establish if field progression had occurred in event-based analyses with 3 points with significant change in 3 consecutive fields using total (TD) and pattern deviation (PD) analysis. Rates of Mean Deviation (MD) change (dB/yr) were also measured. Control analyses were performed to determine if the initial SAP follow-up predicted subsequent SAP progression.
Results: :
The table shows the median survival times (in years) for subsequent visual field progression after optic disc change defined by the 3 TCA criteria for protocols A and B. The survival times for patients showing disc change in the initial follow-up were marginally less those showing no disc change, but these differences were not statistically significant (P > 0.05, log-rank test). Similarly, in each case, patients with disc change consistently had more negative mean MD slopes, however, the difference was statistically significant (P = 0.04, t-test) in only one comparison (*). In the control analyses, patients with previous visual field progression had significantly shorter survival times for visual field progression (P < 0.01) when analysis for TD and PD were performed in both protocols.
Conclusions: :
Patients with previous optic disc progression with the HRT had marginally earlier and higher rates of field progression, however, prior field progression was significantly more predictive for subsequent visual field progression.
Keywords: imaging/image analysis: clinical • perimetry • optic disc