Relationship between ocular risk factors for glaucoma and optic disc rim in normal eyes

Aim To study relationships between reported risk factors for glaucoma and neuroretinal rim area in normal eyes. Methods The Kumejima study participants, 3762 of the 4632 eligible Kumejima residents 40 years and older, underwent a detailed ocular examination including sequential disc stereo photography. In a randomly chosen eye of a subject whose both eyes met the inclusion criteria, fundus photographs of 2474 ophthalmologically normal eyes of the 2474 subjects were analysed by computer-assisted planimetry to measure the disc, rim and beta-peripapillary atrophy (PPA) areas. The rim was divided into the superior and inferior halves by a line connecting the fovea and disc centre. Results The disc, superior and inferior halves rim and beta-PPA areas averaged 2.53 +/- 0.50 (SD), 0.82 +/- 0.15, 0.84 +/- 0.16 and 0.45 +/- 0.66 mm(2). After adjustment for other systemic and ocular factors including age, disc and beta-PPA areas, disc-fovea distance (p=0.013, 0.016) correlated positively and intraocular pressure (IOP) (p=0.004, 0.006) and axial length (AL) (p<0.000, 0.004) negatively with the superior and inferior halves rim area, respectively; central corneal thickness (CCT) (p=0.008) and mean blood pressure (mBP) (p=0.020) correlated positively and male gender (p=0.012) negatively only with the superior half rims. Conclusions Besides previously reported risk factors for glaucoma such as age or IOP, thinner CCT, lower mBP and male gender were newly found to significantly correlate with smaller rim area only in the superior half disc, and a greater disc-fovea distance with greater superior and inferior half rim areas in normal adult eyes.