The outcomes of cataract-surgery the relationships between visual acuity, visual function and quality in life

Abstract

This thesis has assessed the outcomes of cataract surgery not only in terms of clinical measures of impairment and but also using patient perceived measures of disability and handicap. The inter-relationships between these measures and the additional contributions that patient perceived measures can make to the assessment of cataract outcomes have been identified. Two prospective cohort studies were conducted in which patients admitted for surgery for age related cataract were studied. The first of these described current surgical practice and clinical outcomes (visual acuity after surgery and complications) throughout the UK. Patients were followed up for three months and risk factors for poor clinical outcome were identified and quantified. Using Poisson logistic regression analysis, relative risks as measures of effect were calculated for this purpose. The second cohort study was concerned with patients' perceptions of their visual function (disability) and quality of life (handicap), before surgery and at 4 and 12 months after. Visual function was assessed using the VF-14. The Sickness Impact Profile (SIP) was used to assess general quality of life, and its modification, the VRSIP, was used as a vision-specific measure of quality of life. Measures of association (provided by multiple regression and analysis of covariance) were used to examine the relationships between the clinical measure of outcome (visual acuity) and the patient perceived measures. The influence of the sensory input from both eyes on these relationships was examined. Important confounders influencing the extent of change in patient perceived measures achieved after surgery were identified. The findings have implications for clinical practice as regards timing of surgery to maximise benefit, and the additional contribution of second eye surgery. These are discussed together with the role of clinical and patient perceived measures for the assessment of the outcome of cataract surgery.