For low vision specialists and those who consult them
Journal Article: Functional Tests for Low Vision
September 1, 2009Posted by on
I have just read a good paper by Dougherty and colleagues in the August issue of Optometry and Vision Science discussing the development of some new functional tests for low vision research.
A key question of low vision rehabilitation is “how useful is intervention x, y or z?”. This is surprisingly difficult to answer, even when x is as simple as prescribing magnification.
Historically, we answered this question by looking at easy to measure clinical tests, such as visual acuity, contrast sensitivity, reading speed or glare sensitivity. More recently, questionnaires have been used to determine the impact of rehabilitation on vision-related quality of life, using instruments such as the Visual Function Questionnaire (VFQ) or Massof Activity Inventory.
Dougherty and colleagues have used a third approach: to develop some real world tasks, which can be performed under controlled conditions, to measure visual function. These are:
*Reading rate at set print sizes
*Finding a number in a telephone directory
*Identifying prescription medication from a medicine bottle
*Reading utility bills
*Finding cooking time on a food packet
*Sorting coins to total a specified amount
*Identifying a playing card
* Recognising facial expression
To investigate the use of these tasks as a research outcome, the authors investigated the effect of a single low vision appointment on these variables. They found measurable changes on many of the tests, with the biggest improvements in reading medicine bottle labels and cooking instructions.
Using functional tests to measure visual performance is not new, but the development of a standardised battery of visual function tests is an excellent development. It would be extremely beneficial for the field if these tests were adopted by other research groups so that outcomes can be compared between different rehabilitation approaches, in different clinical settings, in different countries.