Abstract
Purpose: :
To assess the effect of age and ocular perfusion pressure on visual field progression in patients with open angle glaucoma (OAG).
Methods: :
103 patients (age 67.1, 59 female) enrolled in the Indianapolis Glaucoma Progression Study were evaluated at baseline and 1.5 years follow up. Central corneal thickness (CCT) was measured by ultrasonic corneal pachymeter. Ocular perfusion pressure (OPP) was calculated as OPP=2/3(mean arterial pressure)-intraocular pressure (IOP). Retinal structural measurements were made using ocular coherence tomography (OCT). Visual fields were assessed by Humphrey Visual Field Analyzer (24-2 SITA standard). Changes in visual fields and its predictability by baseline retinal structural features, age, gender, CCT, OPP and initial AGIS score were evaluated. Bivariate correlations coefficient was estimated by Spearman rank correlation test. To assess the independent contributions of age, gender, initial OPP, CCT, AGIS score and OCT parameters to AGIS score changes, multivariate regression analysis with rank-transformed data was used to obtain the partial correlation coefficients.
Results: :
Changes in AGIS score positively correlated with baseline cup area (r=0.214, P=0.030), cup/disc area ratio (r=0.219, P=0.026), cup/disc horizontal and vertical ratios (r=0.218, P=0.027 and r=0.231, P=0.019, respectively) and macular center (r=0.207, P=0.036). Changes in AGIS score negatively correlated with vertical and horizontal rim width and rim area. Multivariate linear regression model revealed that AGIS score change was negatively associated with baseline rim area (partial rho= -0.253, P= 0.014) independent of age, gender, OPP, CCT and initial AGIS score. In patients less than 70 years (n= 54), only the baseline rim area was an independent predictor of AGIS score changes (partial rho= -0.338, P= 0.022). However, in patients 70 years or older (n= 49), only OPP was an independent predictor of AGIS score changes (partial rho= 0.325, P= 0.034).
Conclusions: :
In OAG patients less than 70 years of age, baseline optic nerve head structure may be the main determinant of early glaucomatous visual field loss. However, in OAG patients older than 70 years, OPP may be more important in predicting visual field progression.
Keywords: aging: visual performance • aging • visual fields