| Author: | Huang, Yeung Chi |
| Title: | Effectiveness of perceptual learning in reading rehabilitation for patients with parafoveal retinal lesions : a paradigm in diabetic macular oedema (a pilot randomized controlled trial) |
| Advisors: | Chan, Henry (SO) Cheong, Allen (SO) |
| Degree: | DHSc |
| Year: | 2017 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Diabetic retinopathy -- Treatment Eye -- Diseases -- Treatment |
| Department: | Faculty of Health and Social Sciences |
| Pages: | xvi, 122 pages : color illustrations |
| Language: | English |
| Abstract: | Introduction: Perceptual learning has shown to be an effective way to improve reading performance in patients with central vision loss due to macular disease. The aim of this study was to investigate the effect of reading rehabilitation using perceptual learning in patients with reading difficulties due to parafoveal retinal lesions. Diabetic macular oedema (DMO) is a severe complication of diabetes. It is also a major cause of visual loss in diabetic patients affecting about 14% of all diabetics particularly in the working age population. Laser photocoagulation is the first-line treatment for most DMO patients worldwide. Previous studies have shown that patients with DMO have good outcomes of best-corrected visual acuity after laser photocoagulation, but their reading speed remains significantly slower than normally-sighted subjects due to the complications after the laser treatment including parafoveal retinal lesions. Objective: The aim of this study was to investigate the effectiveness of reading rehabilitation using perceptual learning in enhancing the reading performance in patients with reading difficulties caused by parafoveal retinal lesions. Methodology: A two-arm randomized controlled trial (RCT) was conducted. Twenty patients with DMO, aged 53 to 69 years, were recruited and randomly assigned into one of the two groups: 1) intervention group in which participants received 6 weekly sessions of temporal and spatial processing training (60 minutes each, n=10); or 2) placebo control group in which participants received 6 weekly sessions of leisure reading activities (n=10). Temporal processing speed and spatial visual span were measured using the trigram character-recognition method, which is similar to a previously described method by Cheong et al. (2008) and Legge et al. (2001) Temporal processing speed was defined as the conversion of the exposure duration yielding 80% recognition accuracy. Spatial visual span was defined as the average recognition accuracy among three characters (central-3, -1 to +1) and five characters at central (central-5, -2 to +2) positions. Reading speed was measured using rapid serial visual presentation (RSVP) and the PolyU Chinese reading-acuity chart. The physiological function of the visual cortex was evaluated by pattern-reversal visual evoked potentials (PVEP) using visual stimuli of -two sizes with -two contrast levels. The National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) was administered to evaluate patient-reported outcome measure. All outcome measures were conducted at two time points: 1) baseline, and 2) immediately after a 6-week intervention period. Main outcome measures: Outcome measures were conducted before and immediately after the training. Primary outcome measures were temporal and spatial properties of visual span measures; secondary outcome measures included visual-evoked potentials, reading performance, fixation stability and visual-related quality of life. Results: Results from mixed-model analysis showed significant improvement in the temporal processing speed (p= 0.003) and spatial visual span (for average proportion correct for the central-3 and central-5 characters, p= 0.001) in the intervention group, but not in the control group. Marginally significant training effect in RSVP reading speed on the larger print size (p = 0.051) was also found in the intervention group. However, the maximum reading speed measured with the PolyU Chinese reading-acuity chart was not significantly different between pre- and post-training for the intervention group. Instead, the maximum reading speed in the control group at the post-training assessment was significantly faster than that at pre-training (p= 0.005). No significant difference was noticed in the PVEP, fixation stability, or NEI-VFQ-25 in both groups (p > 0.05). Conclusion: This pilot study showed that perceptual learning significantly improved the temporal processing speed and spatial visual span in patients with reading difficulties due to parafoveal retinal lesions. This training effect showed a trend in enhancing the reading performance measured with RSVP. However, the training effect could not be transferred into paper-format reading (measured with sentences in the PolyU Chinese reading-acuity chart). Instead, paper-format reading ability could be improved with leisure reading activities using similar visual materials provided in the placebo training for the control group. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 991022052656203411.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 1.21 MB | Adobe PDF | View/Open |
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