Visual impairment and the useful field of vision

The aim of this study was to measure the useful field of vision (UFoV) in people with visual impairment and to compare results with clinical measures of vision. UFoV, visual acuity, contrast sensitivity and visual fields were measured in 36 participants with low vision and 22 age-matched controls in two age groups. For both the low vision and control groups the presence of distractors (cluttered field) increased the error rates on our UFoV measure but there was no significant effect of the presence of a central task (divided attention). Participants with low vision made more errors on UFoV than did controls, but this difference disappeared once their visual field defects were accounted for. By multiple regression analysis, age, visual fields and contrast sensitivity were shown to predict the different UFoV scores. As for observers with normal vision, standard clinical visual field tests may not fully describe the difficulties that may be encountered by people with visual impairment undertaking tasks in the cluttered environments and multiple demands of everday life

Technical Note: Domestic lighting requirements for elderly patients

It is a well established fact that older persons require higher levels of illumination to meet their visual needs, than do younger people. However, most interior lighting standards pay little attention to the needs of older persons. These standards give few recommendations for domestic lighting and rarely does illumination in homes meet the recommended levels. This paper discusses the role of the optometrist in the assessment of the response of older patients to illuminance levels and presents information which can help the optometrist better advise older persons on their domestic lighting requirements

Senile Macular Degeneration: The Effects and Management

This paper aims to identify the population affected by the ocular disease, senile macular degeneration (SMD). We examine the available data on the prevalence and incidence of the disease, the age, sex and race of those affected and risk factors associated with this condition. Using these data, we suggest a profile for the 'typical' patient with SMD.\ud \ud We estimate that there are more that 249000 persons in Australia with SMD in one or both eyes. Approximately 10000 of these are legally blind. With the increasing proportion of aged pesons in our population, private practitioners will be increasingly required to provide vision rehabilitation to persons with SMD

A simplified screening test for identifying people with low vision in developing countries.

Simple but effective tests have been produced for screening subjects with low vision in developing countries. These tests of distance and near vision, based on the E test, were evaluated and validated in trials with people aged 4-90 years, and have been field tested in the health, education and rehabilitation services in 32 developing countries. Their sensitivity and specificity as screening tools for low vision have been calculated; sensitivity of 85% and specificity of 96% for the distance vision test, and sensitivity of 100% and specificity of 84% for the near vision test. The content and format of the tests have been demonstrated to be appropriate for developing countries, and their effectiveness for screening for low vision has been confirmed

What areas of of the visual field are important for mobility in low vision patients

1. The relationship between binocular visual field size and orientation and mobility performance was examined for nine low vision patients and nine age-matched normals. 2. Mobility performance was determined by measuring time taken and number of errors made by subjects on an indoor course. 3. Mobility performance is significantly influenced by the total visual field extent, such that the smaller the solid angle subtended by the total field at the eye, the poorer is the mobility performance. 4. The relationship between visual field and mobility performance varies across the binocular field. The central 37 deg radius zone and right, left and inferior mid-peripheral areas appear to be the most important for mobility. 5. The time taken to traverse the course and the number of errors made are both good predictors of mobility performance, although number of errors correlates more highly with visual field extent. 6. Horizontal objects at head height and large objects on, or suspended just above, the floor are those most likely to present difficulties to low vision patients