Optic Disc Measurements with Personal Computer in Normal Eyes

ABSTRACT

Quantification of the optic nerve head topography is getting more and more important in diagnosis, differential diagnosis and follow-up of optic nerve diseases, especially in glaucoma. This study was undartaken to measura optic disc parameters and further to determine side, gender, age, refractive errorrelated differences in the size and topography of the optic disc. The radius and angle of the optic disc and cup were measured every 30 degrees by a computer graphic program(Adobe Photoshop(TM)) in 142 eyes of 78 normal subjects(37 men, 41 women, mean age 47.2 +/- 14.2). The actual optic disc sizes were corrected based on refraction and anterior corneal curvature utilizing Littmanns method. Optic disc area averaged 2.47 +/- 0.48mm2, vertical disc diameter 1.86 +/- 0.18mm, horizontal disc diameter 1.68 +/- 0.18mm. Optic cup area averaged 0.56 +/- 0.28mm2, vertical cup diameter 0.68 +/- 0.28mm, horizontal cup diameter 0.84 +/- 0.27mm. Neuroretinal rim area averaged 1.90 +/- 0.37mm2 and rim width was widest in the inferior disc pole, followed by the superior, nasal, and temporal poles. A highly significant linear correlation between disc area and rim area was observed(r=0.81, p=0.0001) together with a correlation between the disc area and cup area(r=0.58, p=0.0001). Concerning optic disc area, side differences of 0.25mm2 or less were found in 60% and of 0.5 mm2 or less in 90%. Concerning neuroretinal rim area, side differences of 0.25mm2 or less were found in 73% and of 0.5mm2 or less in 90%. There were no significant correlations between these morphometric optic disc data and side, gender, age, or refractive error.