Changing incidence of lens extraction over 20 years: the Beaver Dam eye study

Objective: To investigate trends in the incidence of lens extraction over the past 20 years.

Design: Longitudinal population-based cohort study.

Participants: Persons who participated in the Beaver Dam Eye Study.

Methods: Eligible persons 43 to 84 years of age living in the city or township of Beaver Dam, Wisconsin, were recruited from 1987 through 1988. Participants were followed up every 5 years from 1993 through 1995, from 1998 through 2000, from 2003 through 2005, and from 2008 through 2010 after the baseline examination from 1988 through 1990. Examinations consisted of ocular examination with lens photography and grading; medical history; and measurements of blood pressure, height, and weight. Adjustments were made for age and gender. Values of risk variables were updated, and the incidence of lens extraction surgery was calculated in each 5-year interval.

Main outcome measures: Incidence of lens extraction with regard to presence of clinically significant lens opacity and visual function.

Results: Age- and gender-adjusted incidence of lens extraction increased over the 4 intervals from 1.8% (95% confidence interval [CI], 1.3%-2.5%) in the interval between the first and second study examinations to 11.7% (95% CI, 9.9%-13.8%) in the most recent study interval. The increase in incidence of surgery was significantly higher at successive intervals in persons without clinically significant lens opacity at each preceding examination (interval 1, 0.8% [95% CI, 0.6%-1.1%]; interval 4, 9.4% [95% CI, 7.8%-11.2%]) compared with persons with at least 1 detectable type of opacity (interval 1, 9.2% [95% CI, 6.4%-13.2%]; interval 4, 16.5% [95% CI, 13.4%-20.0%]). Recency of examination was not attenuated by adjusting for additional risk factors. There was no evidence that the increased incidence in surgery was preceded by poorer visual acuity, near vision, or contrast sensitivity at the beginning of each interval.

Conclusions: The incidence of lens extraction has increased over the past 20 years in persons older than 65 years. The relative increase of surgery is higher in those without any clinically significant lens opacity and in persons with visual acuity better than 20/40 at an examination as measured 5 years before observed incidence of lens extraction.