Annual Database of Intraocular Lens Power in a Taiwanese Population

Background: To derive a unique database of intraocular lens (IOL) power for Taiwanese, an ethnic group with a strikingly high prevalence of myopia. Methods: A retrospective series of 3068 cases visiting Chang Gung Memorial Hospital, Linkou for cataract removal and posterior chamber IOL implantation between July 1999 and June 2000 was reviewed. The distribution of IOL powers and a possible age-correspondence was analyzed by one-way analysis of variance (ANOVA) test and multiple regression. Results: Using the SRK/II linear regression formula, with an "A" constant of 118.5, the mean predicted IOL power required for emmetropia was 20.0±5.1 diopter (D). The mean IOL power for males was 19.8±5.1 D. The mean IOL power for females was 20.1±5.1 D. Moreover, ANOVA results documented a statistically significant tendency of age-dependence for IOL power distribution in the 3 groups (male, female, and male and female; F=24.53, p<0.05; F=16.39, p<0.05; F=40.54; p<0.05, respectively). In particular, it statistically significantly differed among decades over 40 years indicating that IOL power increased with age. However, the implanted IOL power decreased with age in patients younger than 40 years old. Multiple regression analysis showed that age, but not gender, was statistically significantly correlated to the IOL power distribution (p<0.05). Conclusion: We provide a unique database of IOL power for cataract surgeries in Taiwan. An age-related correspondence of the database of IOL powers was also documented in this study, which can therefore be regarded further cross-sectional evidence for the age-dependence prevalence of myopia.