Visual functional outcomes of cataract surgery in the United States, Canada, Denmark, and Spain: report of the International Cataract Surgery Outcomes Study.

Purpose: To compare functional outcomes after cataract surgery performed at 4 sites in 4 countries that have been described as having significant differences in the organization of care and patterns of clinical practice.

Setting: Multicenter cohort study from the United States, Canada, Denmark, and Spain.

Methods: Clinical data and patient interview data were collected preoperatively and 4 months postoperatively. Functional outcomes were assessed by the Visual Function Index (VF-14), a self-reported measure of visual function. Scores on the VF-14 range from 0 (maximum impairment) to 100 (no impairment).

Results: Unilateral surgery was performed in 1073 patients. In this subgroup, the odds of achieving an optimal functional outcome (VF-14 score > or =95) were similar among sites after controlling for differences in case mix. Bilateral surgery was performed in 211 patients. A postoperative visual acuity of 0.50 or better in both eyes was reported in 155 patients. However, 37% of these patients reported visual function impairment (VF-14 score <95).

Conclusions: A previously identified variation in treatment modalities among the 4 sites did not have a significant effect on the odds of achieving an optimal functional outcome. In addition to visual acuity measurements, the VF-14 index provides information on functional outcomes that is useful, especially in studies assessing the benefits of cataract surgery in a public health care setting.