Ways to measure eye health in the workplace are explored by Professor David Thomson as he concludes his short series.
In the second of our two-part series on vision in the workplace, we will consider the principles of vision screening and discuss different vision screening equipment.
Although most of the attributes of vision can be assessed using a few simple charts, the administration of these tests and the interpretation of the subsequent results require some expertise.
Vision screeners are instruments that allow those with minimal knowledge of vision testing to ensure that individuals comply with specific vision standards. The instruments contain a simple optical system so that a variety of test stimuli can be presented to each eye at various simulated distances. Instruments with various degrees of automation or computerisation are also available.
Vision screeners are instruments that allow those with minimal knowledge of vision testing to ensure that individuals comply with specific vision standards."
Most instruments include tests of distance visual acuity, near visual acuity, stereopsis and colour vision. Some also include an assessment of visual acuity at an intermediate distance for users of display screen equipment (DSE) and a variety of binocular vision tests such as phoria and suppression. Top of the range models may include blur tests for long-sightedness, an astigmatism test, contrast sensitivity and a glare test. Some instruments also include a very crude test of peripheral vision.
These instruments are portable and easy to use by those with minimal knowledge of vision assessment. However, the use of non-standard charts and tests is common, and this can produce anomalous results. The artificial test conditions also cast some doubt on the validity of some tests - DSE assessment in particular. Although templates and guidelines for interpreting results are provided by the screeners' manufacturers, it is difficult to determine the evidence base for recommendations.
In the future, vision-screening kiosks may provide an efficient way of providing self-administered health and wellness screening in the workplace.