Abstract
Purpose: :
While many studies have shown an association between peripapillary atrophy (PPA) and glaucoma, relatively less is known about the relationship between PPA change and the rate and extent of optic disc change measured over time. We wanted to study this relationship in a group of patients followed in a longitudinal prospective study.
Methods: :
Our sample contained one eye of 86 patients (baseline age 61.7 ± 12.0 yrs) with early to moderate baseline glaucomatous visual field damage. Patients were followed prospectively for 8.6 ± 3.0 years with images of the optic nerve and peripapillary retina recorded with the Heidelberg Retina Tomograph (HRT) at six–month intervals. The data were processed using customised software (v. 3.0.2) which measured several parameters of PPA. Optic disc change was quantified by the largest cluster of red superpixels within the disc margin in three consecutive examinations using the Topographic Change Analysis (extent of disc change), and global and sectoral rim area regression analysis (rate of disc change).
Results: :
The median (and 90% range) change in PPA area was 0.090 (–0.081, 2.80) mm2, or 20.8 (–15.1, 246.7)% indicating an overall increase in PPA. The corresponding figure for global rim area slope was –5.87 (–47.5, 15.0) x 10–3 mm2/yr. There was however a poor association between the absolute (r = 0.099, P = 0.399) or percentage (r = 0.069, P = 0.562) PPA change and the extent of disc change. Similarly there was no association between these parameters of PPA and rate of disc change (r = –0.010, P = 0.933 and r = 0.093, P = 0.416 respectively). The analysis of sectoral disc changes also yielded poor relationships with PPA changes.
Conclusions: :
In this cohort of glaucoma patients, changes in PPA occurred frequently, however, they are not associated with the extent and rate of disc change. These results suggest that the mechanisms of PPA and disc change may be independent.
Keywords: optic disc • imaging/image analysis: clinical • clinical (human) or epidemiologic studies: prevalence/incidence