Nerve fibre layer measurement of the Hong Kong Chinese population by scanning laser polarimetry.

Abstract

To obtain normal retinal nerve fibre layer (RNFL) measurements by scanning laser polarimetry in a local Hong Kong Chinese population and to identify the correlation of the measurements with age. One hundred and fifty-nine normal Hong Kong Chinese volunteers of different ages were recruited for this study. RNFL values were measured using a Nerve Fibre Analyzer GDx (Laser Diagnostic Technologies, CA). Mean peripapillary RNFL measurements at the superior, inferior, temporal and nasal regions were 95.0 +/- 15.6, 97.0 +/- 16.3, 47.0 +/- 9.0 and 43.9 +/- 15.1 microns respectively (mean +/- SD). There was a highly significant negative correlation in average RNFL values with increasing age (approximately 1.9 microns per decade, p = 0.001). A significant negative correlation with increasing age was also identified in the RNFL values in all four regions and they decreased by similar amounts (p < 0.05). No correlation with age was observed for relative ratio parameters such as superior/nasal ratio, inferior/nasal ratio and max. modulation (p > 0.05). RNFL values of the Hong Kong Chinese population appeared to decrease over time cross-sectionally. Since they decreased by similar amounts at four regions, use of relative ratio parameters for analysis has an advantage over absolute values, as they were not affected by age.