The use of portable electronic vision enhancement systems by the visually impaired (the p-EVES study).

Abstract

The p-EVES study was designed to assess the effectiveness of portable electronic vision enhancement systems (p-EVES) compared with conventional optical aids for near vision tasks in patients with low vision. The author of this thesis was the clinician researcher on the study and this thesis presents selected data from the study.A literature review explores the epidemiology of low vision, the impact that having low vision can have on the patient and the current systems for service provision in the UK. Optical and electronic magnifiers are considered, and their advantages and disadvantages reviewed.A focus group was held at the beginning of the p-EVES study in order to choose the devices to be used in the study. A total of 16 devices were evaluated, and four devices were selected for the study. Recruitment and the initial assessment of p-EVES participants were undertaken by the clinician researcher. The California Central Visual Fields Test (CCVFT) has not been widely used to measure central scotoma, but it allowed binocular scotomas to be evaluated. A grading system was designed, and 92% of participants were found to have a central scotoma. The grading system showed significant correlations with visual acuity and contrast sensitivity measurements and no significant correlation with maximum reading speed. Participants needed instruction in how to use the p-EVES devices at home so task-based practice was undertaken. It was found that this took between 5 and 30 minutes per participant. A difficulties questionnaire administered one week following prescription of p-EVES found that only 2 individuals were having technical difficulties using the device. . A maximum variation sampling method was used to select 27 participants for interview. Previous guidance on prescribing p-EVES devices was derived from clinical experience. The difficulties questionnaire and the interview transcripts now allow the presentation of some evidence-based guidelines for prescribing p-EVES.

Date of Award	31 Dec 2016
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Chris Dickinson (Supervisor) & Robert Harper (Supervisor)