Incidence and Rates of Visual Field Progression after Longitudinally Measured Optic Disc Change in Glaucoma
Received 17 January 2009; received in revised form 10 April 2009; accepted 15 April 2009. published online 04 June 2009.
Objective
To determine whether glaucoma patients with progressive optic disc change have subsequent visual field progression earlier and at a faster rate compared with those without disc change.
Design
Prospective, longitudinal, cohort study.
Participants and Controls
Eighty-one patients with open-angle glaucoma.
Methods
Patients underwent confocal scanning laser tomography and standard automated perimetry every 6 months. The complete follow-up was divided into initial and subsequent periods. Two initial periods—first 3 years (Protocol A) and first half of the total follow-up (Protocol B)—were used, with the respective remainder being the subsequent follow-up. Disc change during the initial follow-up was determined with liberal, moderate, or conservative criteria of the Topographic Change Analysis. Subsequent field progression was determined with significant pattern deviation change in ≥3 locations (criterion used in the Early Manifest Glaucoma Trial). As a control analysis, field change during the initial follow-up was determined with significant pattern deviation change in ≥1, ≥2, or ≥3 locations.
Main Outcome Measures
Survival time to subsequent field progression, rates of mean deviation (MD) change, and positive and negative likelihood ratios.
Results
The median (interquartile range) total follow-up was 11.0 (8.0–12.0) years with 22 (18–24) examinations. More patients had disc changes during the initial follow-up compared with field changes. The mean time to field progression was consistently shorter (protocol A, 0.8–1.7 years; protocol B, 0.3–0.7 years) in patients with prior disc change. In the control analysis, patients with prior field change had statistically earlier subsequent field progression (protocol A, 2.9–3.0 years; protocol B, 0.7–0.9). Similarly, patients with either prior disc or field change always had worse mean rates of subsequent MD change, although the distributions overlapped widely. Patients with subsequent field progression were up to 3 times more likely to have prior disc change compared with those without, and up to 5 times more likely to have prior field change compared with those without.
Conclusions
Longitudinally measured optic disc change is predictive of subsequent visual field progression and may be an efficacious end point for functional outcomes in clinical studies and trials in glaucoma.
Financial Disclosure(s)
The authors have no proprietary or commercial interest in any of the materials discussed in this article.
Available online: June 4, 2009.
Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
Correspondence: Balwantray C. Chauhan, PhD, Department of Ophthalmology and Visual Sciences, Dalhousie University, 1276 South Park Street, 2W Victoria, Halifax, NS, Canada B3H 2Y9
Manuscript no. 2009-75.
Supported by Grant MOP11357 from the Canadian Institutes of Health Research (BCC).
ABSTRACT