Improving the detection of correctable low vision in older people

Jessa, Zahra (2009). Improving the detection of correctable low vision in older people. (Unpublished Doctoral thesis, City University London)

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Abstract

In the UK, 20-50% of older people have undetected reduced vision and in most of these cases the poor vision can be readily corrected by new spectacles and/or cataract surgery. It is often assumed that older people with vision loss will have regular eye examinations so that these problems can be detected, but for many older people this assumption is wrong. One approach to improving the take-up of eyecare services is to carry out vision screening of older people in the community to raise awareness of the need for professional eyecare.

The present study aimed to investigate which tests would be most appropriate to screen for correctable visual loss in the older population and to incorporate these tests in a screening tool that would be effective yet simple to administer. The present research sought to investigate whether computerised techniques would be an effective method to screen vision in older people.

In Study 1, a computerised vision screener was used to test 180 older people in South London. All participants also received a full, ‘gold standard’, eye examination. Significant cataract was present in 32%, correctable refractive error in 39%, and overall 58% had at least one of these forms of correctable visual problems. The computerised vision screener was able to detect these conditions in about 80% of cases. In Study 2, 200 participants were screened using a revised version of the computerised vision screener. A new flipchart vision screener including the main tests from the computer vision screener was also investigated. 31% of participants in Study 2 had significant cataracts, 30% had correctable refractive errors, and 51% had at least one of these conditions.

The computer screener and flipchart tool were both good at detecting significant cataract and refractive errors. About 80% of cases of visual loss due to these problems or due to AMD could be detected with either of the screening tools. Using a pragmatic operational criterion, the screening tools detect about 94% of cases who might be considered by an optometrist to be in need of an eye examination (either overdue or reduced visual acuity). Glaucoma is a difficult disease to diagnose and it was found, as expected, that neither screening instrument was very good at detecting glaucoma.

The results showed that the best single test to use for screening of visual loss is HCVA which provides both a high sensitivity (77%) and specificity (73%). Greater sensitivity (80%) is achieved when high contract acuity, low contrast acuity and near acuity are used in combination. Greater specificity (77%) can be achieved by using low contrast acuity alone.

It is concluded that vision screening does not replace the need for professional eyecare, but acts as a tool to better inform the public of the need for regular eyecare.

Item Type: Thesis (Doctoral)
Subjects: R Medicine > RE Ophthalmology
Divisions: School of Health Sciences > Department of Optometry & Visual Science
URI: http://openaccess.city.ac.uk/id/eprint/12443

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