Abstract
Purpose: :
To measure automatically disc area (ODA), its horizontal (HD) and vertical (VD) diameters and the angle aberration of the transverse axis to the related horizontal axis in normal subjects and patients with glaucomatous optic atrophy (GOA) and optic nerve head drusen (ONHD).
Methods: :
Both eyes were examined in a standard population (965 male and 664 female subjects, age 47.2±10.8 years) by a non–mydriatic fundus camera (KOWA 45° alpha). Among 3124 eyes were eyes suspicious for GOA (16 in woman; 15 in men), eyes with manifest GOA (3 in woman; 5 in men), and eyes with ONHD (3 in woman and men each). An automated algorithm was used to approximate the contour of the optic disc by an ellipse, using pattern recognition methods. ODA, HD and VD were measured automatically.
Results: :
Of all eyes ODA was 2.12±0.38 mm2 [2.5th and 97.5th percentile, 1.51; 2.99 mm2], HD was 1.62±0.15 mm [1.35; 1.95 mm] and VD was 1.65±0.15 mm [1.38; 1.97 mm]. The angle aberration was +2.2±24.7° [–42.7; +42.4] for the right eye (OR) and –4.6±23.5° [–42.8; +41.6] for the left eye (OS), p=0.10 after correction for algebraic sign. ODA, HD and VD did not differ between OD and OS. Within the refraction range of –5 to +5 D age was correlated to ODA (OD 0.151, p<0.001; OS 0.129, p=0.002), HD (OD 0.159, p<0.001; OS 0.130, p=0.002), and VD (OD 0.130, p=0.002; OS 0.112, p=0.007) but not the refractive error, body height or gender, if controlled for the other variables each.
Conclusions: :
The automated method to outline the optic nerve head margin give results, which are in good agreement with the literature. The cause for the significant correlation of disc area with age is unknown.
Keywords: wound healing • imaging/image analysis: clinical • optic disc