Cataract surgery: new assessment technique targets better understanding of treatment outcomes

Posted: 15/05/2018

To quote the first line of a recent paper, ‘Cataract is a common, potentially blinding eye disease with an adverse impact on quality of life for which surgery is the only effective treatment’. [Cataract surgery patient reported outcome measures – Eye (2018)32 788-795]

In England, over 390,000 cataract operations were undertaken during the year 2015/16. Treatment takes place in about seven per thousand of the population.

Taking account of the overall impact of cataract in a patient's life is increasingly important. Traditionally the success of surgery was based on an assessment of visual impairment before and after surgery of monocular visual acuity assessed using a Snellen letter chart, a technique which began in late Victorian times.

However that formal assessment of what a patient can see over a fixed distance fails to cover the wide range of problems and functional consequences of visual impairment caused by cataract, not least as to the involvement of other diseases that may affect the eyesight.

Partly as a result of a widening of the appreciation and recognition of disability on a worldwide basis, a Patient Reported Outcome Measure (PROM) approach has found more favour in recent years. This is seen as a better assessment of whether treatment has worked.

NICE guidance in 2017, following Royal College of Ophthalmologists guidelines in 2015, recommended further research into self-reported assessment of visual disability caused by cataract. Perhaps the thinking behind this is that some patients will be more accepting of symptoms and will seek less treatment, whereas others will be more demanding.

This new assessment process requires a questionnaire drafted in simple English. A rather complex system of statistical assessment was made of such questionnaires in use in other health systems and environments.

Through a process of trials of patients and check testing, a questionnaire named ‘CatD-PROM5’ was created. This asks five questions about interference with eyesight with multiple-choice answers, each of which is assigned a defined score. The scores are totted up at the end to provide a numerical measure of disability.

In tests and repeat tests, these results have shown a high degree of precision and patient acceptance in making assessments of the quality of the results of surgery, and also most importantly in informing treatment choices.

Tim Wright, senior associate in the clinical negligence team in Penningtons Manches’ Basingstoke office, comments: “A great deal of work has been put into producing this simple tool, which will provide better patient understanding in approaching cataract surgery. Given the number of people who undergo surgery of this type, it should prove beneficial for a significant proportion of the population.”

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