The morphology of the optic nerve head in the Singaporean Chinese population (the Tanjong Pagar study): part 2--Biometric and systemic associations.

BACKGROUND/AIMS: To investigate the association of biometric and systemic variables with optic disc characteristics in Chinese Singaporean adults. METHODS: Ocular, biometric and medical data including intraocular pressure, refractive error, keratometry, axial length (AL), anterior chamber depth, corneal and lens thickness as well as optic disc data (using planimetry of stereo-photographs) were obtained from 622 normal subjects aged > or = 40 years from the Tanjong Pagar glaucoma survey of Singapore. RESULTS: Disc area (DA) was positively associated with AL and height but was unrelated to corneal thickness. Following adjustment for IOP and sex, DA remained positively associated with AL, height and age. Neuroretinal rim area (RA) was also significantly and positively associated with AL and also with height. RA was negatively associated with IOP and was unrelated to blood pressure, history of diabetes, myocardial infarction, stroke or migraine. CONCLUSIONS: These data on a Chinese Singaporean population identify height and axial length of the globe as significantly associated with rim area of the disc. These features should be taken into account in statistical assessments of optic nerve head morphometry. This may improve the discriminative ability of image analysis to detect glaucomatous changes. In addition, we identified a statistically significant but small inverse association between rim area and IOP within the normal statistical range.