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Cataract Surgery: Measuring and predicting patient level vision related health benefits and harms

Funding body/stream

NIHR - Programme Grant for Applied Research

Chief investigator

Professor John Sparrow


University Hospitals Bristol NHS Foundation Trust

Start dateand duration

1st December 2013 for 5 years




Cataract is an extremely common potentially blinding age related condition. Cataract surgery is the most frequently undertaken surgical procedure on the NHS (~330,000 annually in England). Before and after surgery vision testing is normally done one eye at a time using the (opticians) letter chart. Although useful, testing in this way does not capture people's everyday experience of their vision. Asking patients about everyday vision, in a structured way, allows the patient's perception of their eyesight to be 'measured'.

Measuring: Our first objective will be to develop and test a suitable set of questions (Cat-PROM) for eliciting self-reported vision information from people with cataract. Testing will be done both before and after surgery to check that the questions work as intended.

Harm: All surgery can have complications and cause harm to patients. Although fairly uncommon in cataract surgery (1-2 per 100) harmful events must be avoided whenever possible. From our studies of 55,567 operations we know that the averages can hide a lot of variation depending on patient factors, with a small proportion of complex patients being at very high risk. If there is a complication then there is a 6x higher likelihood of vision loss following surgery. We will check our results for prediction of adverse events using ~200,000 fresh electronic patient cataract care records. Statistically, big numbers are needed to analyse these uncommon adverse events.

Benefit: Understanding the risk of harm is just one aspect of weighing things up when considering possible surgery. Patients also need to know how likely it is that surgery will be successful. Statistically, smaller numbers are required to study this because favourable outcomes are more frequent. To understand different gradations of benefit however, additional preoperative details not routinely collected are needed e.g. cataract severity. From detailed clinical assessments of 1500 people before and after surgery we will identify important preoperative features associated with better or poorer self-reported Cat-PROM outcomes.

Health Economics: The National Institute for Health and Clinical Excellence (NICE) uses a patient Quality-of-Life self-report questionnaire (EQ5D) when deciding on NHS spending. Moderate vision problems are not adequately detected by the EQ5D. We will ask subgroups of the 1500 people to complete it along with other Quality-of-Life questionnaires, and link these to Cat-PROM scores for future health economics studies.

Decision Support: Empowerment of patients considering cataract surgery will be achieved through clear presentation of personalised information on risks of harm and likely patient-reported visual benefit from cataract surgery using a frequently asked question style of 'Option Grid'. The usefulness of this information for patients and health care providers will be evaluated in regard to shared patient-clinician decision making.


The overarching aim is to improve preoperative decision making in cataract surgery through provision of evidence-based, quantitative decision-support information on likely patient-reported benefits and risks of harm for individual patients and to investigate cost issues.

This programme will provide new knowledge through delivery of a robust NHS suitable patient-reported outcome measure for cataract (Cat-PROM), quantification and validation of predictors of surgical benefit and harm, health utility calibration, Option Grid decision-support incorporating integrated personalised benefit / risk calculator tools, and assessment of initial implementation of decision-support. Risk based personalised accessible  patient relevant information will promote equity through consistency of decision making.

Only by providing such personalised information will patients be in a position to weigh up and assess for themselves whether they wish to proceed with surgery or not. This information will empower patients through devolving decision making to them such that they are able to assess potential risks and benefits from the perspective of their own attitudes to risk.


Outputs will be presented at academic meetings including the Annual Congress of the Royal College of Ophthalmologists but also at meetings relevant to research, clinical and social science disciplines appropriate to particular work. We will encourage members of our Patient Advisory Group to participate in co-presentation. Reports will be submitted to research and scholarly journals for publications strengthening the formal evidence base. The Option Grid will in addition be published and freely available on the internet page of the Decision Laboratory, Institute of Primary Care & Public Health, Cardiff University

Patient and public involvement

The programme team are committed to patient and public involvement (PPI) throughout the life of this research programme, from design through to dissemination, and across all the work packages. One team member (Prof Evans) takes a regional lead on PPI through People and Research West of England and works nationally as a member of INVOLVE.

PPI in research with cataract patients is underdeveloped nationally; unlike long-term conditions such as rheumatoid arthritis where patients have ongoing relationships with clinicians and researchers, cataract patients have more episodic clinical encounters, making involvement more challenging. Nonetheless, we have taken important first steps and have ambitious plans to develop PPI more fully.

First, we have drawn on cataract patient experiences to develop our instruments. Patient-reported visual disability guided the development of both of our published Vision Related Quality of Life instruments, which we are combining to form the Cat-PROM instrument that will be used in the research. At the outset 40 in-depth interviews were conducted with cataract patients for the VSQ and 38 for the VCM1, with subsequent operationalisation involving a further 58 ophthalmic patients. This high level of user input preceded formal questionnaire piloting.

Second, we have initiated a Patient Advisory Group from which vital patient experience perspectives on the design of the research were obtained. Patients strongly supported the main aims of the research, and confirmed that they as patients would welcome more individualised decision support for weighing the risks and benefits of cataract surgery. We will continue recruitment to maintain a group size of eight members, and to support their development to contribute to all aspects of the research. The overseeing Programme Steering Committee will include a patient representative and will draw on the wider experience of Patient Advisory Group members. These individuals will be integrated into both running and interpretative aspects of the research.

Training and support will be offered through People and Research West of England. Patient Advisory Group members will be offered general introduction to research training, and further specific training relevant to the different roles they may play in the programme. Training will be provided to enable Group members to contribute effectively to key programme elements, including the Cat-PROM, and experience of the use of the risk-based shared patient clinician decision support tools. For those involved in the qualitative research, in-depth training will be offered covering qualitative research methodology, data collection and analysis. Individual mentoring will be provided through People and Research SW. Further development opportunities including co-presenting conference papers will be available. RNIB will assist dissemination of findings.

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