Long-term results of cataract surgery in type 2 diabetics, a 20-year prospective longitudinal study

To investigate the 20-year outcome, in best-corrected visual acuity (BCVA), and subjective visual function (VF-questionnaire, VF-14) after cataract surgery in type 2 diabetics, compared with non-diabetics.

109 type 2 diabetics and 698 non-diabetics, who had cataract surgery during 1 year at one institution, were included in this prospective, longitudinal, population-based cohort study. BCVA and VF-14 responses were recorded pre- and postoperatively, and every 5 years up to 20 years after surgery. Retinopathy was graded before surgery.

There was no significant difference between diabetics and non-diabetics, in change in BCVA from 10 years or more after surgery, p = 0.45, p = 0.44 and p = 0.83, at 10, 15 and 20 years, respectively, as well as in self-perceived visual function (VF-14) at any time after surgery, p = 0.72, p = 0.20 and p = 0.78, 10-20 years, respectively. At any follow-up, there was no significant difference in BCVA in relation to retinopathy level before surgery, p = 0.1 at 20 years. There was a trend from 10 years after surgery and onward that patients with no retinopathy at baseline lost fewer letters during the 20 years than diabetics with retinopathy. Patients with known type 2 diabetes at surgery had a significantly lower survival compared with the non-diabetics at each follow-up, p = 0.003.

In surviving diabetics, BCVA and subjective visual function were retained in most cases up to 20 years after cataract surgery. Cataract extraction is effective in causing a sustainable improvement in visual function also in type 2 diabetics. Knowledge of these long-term outcomes is essential when counselling diabetics for cataract surgery.