Impact of cataract surgery on visual acuity and subjective functional outcomes:: a population-based study in Sweden

Purpose First, to determine the effects of cataract surgery on subjectively experienced visual function and visual acuity in a defined population, at a specific frequency of surgery. Secondly, to validate questionnaire data regarding the visual function of cataract patients. Methods A prospective population-based investigation of the subjective visual functional and visual acuity outcomes of cataract surgery over al year time interval at one institution was conducted. All operated cases (n = 459) were grouped into three levels of visual impairment, according to the preoperative visual acuities of their better eyes. Subjective reading, TV watching, distance estimation and ability to orientate in unfamiliar surroundings, before and after surgery, were assessed using self-administered questionnaires. The subjective outcomes were related to the subjects' postoperative visual acuities. The statistical evaluations comprised analyses of variance, Yates'-corrected chi-squared tests, weighted kappa and correlation statistics. Results The pre-operative subjective visual disabilities of the patients were significantly correlated with the pre-operative visual acuities of the patients' better eyes. There was an improvement in subjective reading ability, distance estimation and ability to orientate in unfamiliar surroundings for most patients at all three pre-operative visual acuity levels. After surgery there was a stronger correlation between the subjective functional improvement and the increase in visual acuity for the operated eye than for the better eye. Conclusions An incidence of cataract surgery of 3.3 per 1000 population for the year the present study was conducted seems not to be an over-utilisation of resources. Irrespective of the visual acuity level before cataract surgery, the vast majority of patients gain better subjective visual function and better acuity after surgery. It is possible to gain valid information from cataract surgery patients using a short questionnaire.