The morphology of the optic nerve head in the Singaporean Chinese population (the Tanjong Pagar study): part 1 - optic nerve head morphology

Background/aims: To investigate the correlation between optic disc parameters and their association with demographic variables in a Chinese population. Methods: Disc data were obtained from 929 subjects aged >= 40 years from the Tanjong Pagar glaucoma survey of Singapore, using a novel planimetric method of sequential stereo-photographs. Biometric data (refractive error, keratometry, axial length, anterior chamber depth, lens thickness) were used to calculate ocular magnification. Camera magnification was quantified with a model eye. A normal'' dataset of 622 subjects was generated by exclusion of subjects with abnormal results on psychophysical testing, an occludable angle or an intraocular pressure >97.5th percentile in either eye. Results: Median disc area (DA), cup area (CA), and rim area (RA) were 2.09 (range 1.28-4.01) mm(2), 0.69 (0.01-1.90) mm(2) and 1.38 (0.82-2.50) mm(2), respectively. There was strong evidence of an association between DA and RA (Spearman's rho 0.624, p<0.001). DA and RA were significantly greater in men (median DA= 2.20; range 1.30-3.56; median RA, 1.45; range 0.85-2.30) than women (median DA, 2.00; range 1.28-4.01; median RA, 1.36; range 0.82-2.49, p<0.001). DA increased with age (Spearman's rho 0.115, p = 0.004), while RA was unrelated (rho -0.041; p = 0.308). Conclusions: The morphometric characteristics of optic discs in Chinese Singaporeans are very similar to those described in other groups, with the temporal sector rim having the smallest area. Disc and rim areas vary with sex (men. women). Disc area (but not that of the rim) increases with age.