Age-related cataracts are the most common cause of visual impairment and blindness worldwide with few consistently identified risk factors other than aging. There are likely to be numerous reasons for inconsistency between studies, including differences in study design, methods of assessment, analytic approaches, and population differences. A recent article by Leuschen et al1 reporting an association of statin use with increased risk of cataract highlights some possible causes for these discrepancies among studies. The authors used a large military administrative database, selecting 13 626 statin users and 32 623 nonusers aged 30 to 85 years from all patients who were enrolled at baseline from October 1, 2003, to September 30, 2005, and followed up for outcomes from October 1, 2005, to March 1, 2010. Statin users received and filled at least 1 prescription for a statin medication for at least 90 days from October 1, 2004, to September 30, 2005. Nonusers did not receive a statin prescription at any time during the study period. Of these 46 249 persons, 6972 pairs (13 944 persons) were matched on a propensity score composed of 44 characteristics that the authors thought would be associated with statin use. Of note is that some potentially important confounders are omitted (eg, race/ethnicity, education, socioeconomic status). Cataract status was identified based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes that occurred during a follow-up visit. It was unclear whether a cataract code could have also been reported prior to the follow-up period. In the matched analyses, the authors found that the overall risk of cataract was 1.09 (95% CI, 1.02-1.17) for statin users; however, this is no longer significant when secondary cataracts are separated from nonsecondary cataracts. In another analysis that was not matched but was adjusted for baseline characteristics in a subset of persons (6113 statin users and 27 400 nonusers) with no Charlson Comorbidity Index score, based on presence or absence of several medical conditions, the statin users had an odds ratio of 1.25 (95% CI, 1.14-1.38). This was attenuated after adjustment for low-density lipoprotein cholesterol level. However, the odds ratio was not given when only those with nonsecondary cataract were considered alone.