Although low vision is often perceived as loss of visual acuity, or of central visual function, this is not the only way in which vision can be impaired. Visual field loss is associated with functional difficulty in several areas of activities of daily living, and is included as a reason for visual impairment registration, with terms such as ‘contraction of visual field’ and ‘marked field defect’ used in registration guidance (Department of Health 2013).
In general clinical practice, visual field tests are usually conducted to detect or monitor eye disease. However, in low-vision practice visual field assessments are needed to reflect functional difficulties and to guide rehabilitative strategies, but no test currently available is optimised for determining functional consequences of visual field loss. Perhaps partly due to a lack of standardised test, visual fields, other than central scotoma assessment, are not commonly measured in low-vision assessments. Another factor limiting the use of visual fields may be that the value in assessing them is not as clear. A measurement of visual acuity can be the starting point for assessing magnification needs from optical aids, but the eye care practitioner can do very little with regard to optical interventions for restricted visual fields.
The purpose of this article is to review the impact of visual field loss on everyday life, outline the properties of an ideal visual field test for the low-vision assessment, and review currently available methods of functional field assessment. The ways in which practitioners can utilise the information from functional field tests are then discussed.
Login or join the College to read more and take the CET quiz.