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M. Tamura, K. Sasaki, Y. Sakamoto, N. Hatsusaka, D. Lin, H.-M. Cheng, F. Jonasson, H. Sasaki; A Comparison of Ocular Structure and Optical Systems in Eyes of Middle-Aged Taiwanese and Icelanders. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6305.
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To characterize and compare the anterior segment and the optical system of the eyes of middle-aged Taiwanese (T-group) and Icelanders (R-group).
The T-group consisted of 647 cases out of 899 randomly selected participants who were over 40 years old and who had resided for >20 years in Taichung City, Taiwan. The mean age of the subjects was 55.4±9.6 years. Only the right eyes were analyzed. The R-group included the right eyes of 636 participants out of 846 randomly selected from the 2nd Reykjavik Eye Study in Iceland in 2001. Their mean age, SD was (67.7±8.2 years). The axial length, corneal curvature, and the anterior chamber depth were examined by using an IOL Master (Zeiss). For the R-group, ultrasound A-mode was used to measure the axial length. The data were corrected for the difference between optical and ultrasound measurements based on the 3rd Reykjavik Eye Study (2008) in which the IOL Master was used.
The height and axial length showed significant positive correlation in both groups however, the mean height was 13cm shorter in the T-group than in the R-group. The axial length in the T-group (24.06 mm) and the R-group (23.73 mm) showed no significant difference. In terms of the refractive error, the spherical equivalent correlated positively with age in both groups; however, the T-group has a significant myopic shift (-1.03D) when compared with that of the R-group (p<0.001,ANCOVA). In addition, for the same axial length, the corneal radius of curvature and the anterior chamber depth of the T-group were 0.18 mm shorter and 0.13 mm shallower, respectively, than that of the R-group.
The shorter corneal radius of curvature of the T-group at the same axial length as that of the R-group, suggests that the eyes in the T-group are more prolate in shape which can help explain the myopic shift in these eyes.
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