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C.L. Alley, C. Danzig, J.H. Membreno, J.P. Gaughan, V. Baldassano; Comparison of Axial Lengths and Intraocular Lens Implant Powers among Populations from Urban United States, Nicaragua, Dominican Republic and Vietnam . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4471.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the range and variance of intraocular lens (IOL) implant powers required for cataract surgery patients in different world populations based on axial lengths and keratometric powers. Methods: The axial length, keratometric powers, age, and calculated IOL powers were obtained from 156 patients in an urban United States (US) hospital, 204 patients in Nicaragua, 100 patients in the Dominican Republic and 100 patients in Vietnam using the same technique. The patients from Nicaragua, Dominican Republic and Vietnam are from underserved areas and were treated during surgical missions. The population values were compared using accepted statistical methodology. Results: There was no statistically significant difference in the age ranges of the patients from the various populations studied. The mean axial lengths of the various groups were: urban US 23.60mm +/- 0.97 (20.68-27.89), Nicaragua 23.09mm +/- 0.97 (20.47-25.88), Dominican Republic 22.86mm +/- 0.80 (22.96-24.76) and Vietnam 22.74mm +/-1.34 (20.39-28.27). There was a statistically significant difference in the mean axial lengths of eyes in the urban US population compared to each of the other three populations (p<0.0010 in all cases). The mean calculated IOL powers were: urban US 19.90D +/-3.30 (6.18-27.91), Nicaragua 21.91D+/-2.28 (14.92-28.67), Dominican Republic 21.45D+/-2.01 (16.42-28.15) and Vietnam 21.88D +/-3.12 (8.16-29.46). There was a statistically significant difference in the IOL power in the urban US population compared to each of the other three populations (p<0.0010 in all cases). Conclusion: This study determined that the mean axial length and calculated IOL power vary significantly among urban United States and three other world populations. Of the four populations studied, the US patients had the longest axial lengths, and required the lowest IOL powers. Vietnamese patients had the shortest eyes and required the highest IOL powers. Average ocular measurements and calculated IOL powers collected from one population cannot be applied to other populations. The mean IOL power and distribution of powers should be considered individually for each population group. This study suggests the need for similar analysis of other prospective sites to obtain accurate population means and ranges of IOL powers to stock when planning surgical missions to these locations.
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