In seeking a theoretical framework for quality of life, the OPENspace research centre has focused on a social rather than a medical model. While the latter is associated with the absence of illness, the social model embraces ideas such as self-efficacy, perceived control, autonomy and independence, and stress, in addition to more predictable dimensions of pleasure and satisfaction, and seems more appropriate for our research agenda (Hyde et al., 2003; Little, 1998). However, in research focused on studying the quality of life of visually impaired people, there has been to date a simpler approach (Mangione et al., 1992). The definition of quality of life (or more specifically ‘vision related quality of life’) is the degree to which a person’s vision prevents them carrying out a range of daily tasks (e.g. reading, shopping, recognizing faces). While conventional, vision-related quality of life questionnaires explore this (Mangione et al., 2001; Massof, 1995), they do not pursue the relative priority or utility of these tasks; yet the practical consequences of vision loss to a person’s quality of life are influenced by the priority given to different tasks which the person finds difficult to carry out. This is a key issue across many health-related fields, both in the allocation of limited resources and also in developing recommendations for rehabilitation or coping strategies for people (NICE, 2004). The UK National Institute for Clinical Excellence (NICE) has recommended that studies about the value or utility of health care interventions should not use rating scales but instead methods such as discrete choice or conjoint analysis. All the methods recommended by NICE are characterised by a person making a relative choice between alternative situations from which importance or value can be derived.