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 | health surveys | how and why
What is the VF-14 questionnaire?
The VF-14 is a health survey questionnaire designed specifically for ophthalmology. "VF" stands for Visual Function, and "14" refers to the 14 questions in the main section of the questionnaire.
While the SF-36 questionnaire has been shown to produce useful data in a wide range of studies, the VF-14 has been developed to address the particular challenges of measuring how sight affects health status. A general health questionnaire needs to ask a range of questions about mobility, pain, energy etc., but these aspects are affected in different ways in people with sight problems, especially cataract. The blurred vision that is usually the consequence of a developing cataract does not cause any pain, and at least at first has little impact on a person's mobility or energy level. This is especially true now that cataracts are often treated at a very early stage in their progression. For these reasons a questionnaire like the SF-36 could not be expected to reveal the subtlest changes in health in a patient who has a cataract removed.
Instead, the VF-14 asks questions about the person's ability to do everyday tasks, such as reading or sewing, where any blurring of vision could be expected to have an impact. By assessing the person's vision-related health before cataract surgery, and then asking those same questions four months later (when the person would probably have fully recovered) we can measure just how much their life has been improved.
Examples of questions include:
- Do you have any difficulty, even with glasses,
- Reading small print such as labels on medicine bottles, a telephone book, food labels?
- Taking part in sports like bowling, handball, tennis, golf?
- If Yes for either question, how much difficulty do you currently have?
- A little
- A moderate amount
- A great deal
- Are you unable to do the activity?
Ophthalmologists are increasingly aware that this information is important in checking the quality of their surgical techniques. Traditionally, vision (and any improvement in sight) was measured by asking the patient to read small letters from a board (the "Snellen" test). Yet researchers have been puzzled to find that a person might have a good Snellen test result but still have difficulty watching TV, or driving a car - particularly at night. For this reason, the questionnaire includes two questions about driving:
- How much difficulty do you have driving during the day because of your vision?
- How much difficulty do you have driving at night because of your vision?
If the person currently doesn't drive, it also asks if he or she used to drive, and why this is no longer the case. The questionnaire is therefore equally valid, whether the person uses a car or not.
By the same token, there are other questions that not everyone will find relevant, for example "doing fine handwork like sewing, knitting, crocheting or carpentry". These pursuits are not as common as they used to be, but if the person does none of these things, the answer is to tick the box "Not applicable", in which case the question does not have any input to the person's final score.
Links
Why does Bupa measure health outcomes?
What is the SF-36 questionnaire?
Health outcomes of Bupa operations
How to interpret physical and mental health scores
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