| Author: | Fung, Man Yan Mavis |
| Title: | Effect of simultaneous dual-focus integration on electro-retinal activities in the human eye |
| Advisors: | Chan, Henry (SO) |
| Degree: | DHSc |
| Year: | 2019 |
| Subject: | Contact lenses Myopia -- Treatment Hong Kong Polytechnic University -- Dissertations |
| Department: | Faculty of Health and Social Sciences |
| Pages: | xv, 112 pages : color illustrations |
| Language: | English |
| Abstract: | Introduction: The simultaneous dual-focus (DF) contact lens, a treatment option for myopia control, comprises a central zone and a series of alternating defocusing and correction zones that simultaneously produce a clear distance retinal image and myopic defocus. This study was to evaluate how the retinal activities reacts to the induced simultaneous DF during wearing the DF lens. Objectives: 1. To investigate the effects of DF contact lens-induced simultaneous DF integration with different defocus powers on electro-retinal activities and 2. To investigate the time effect of DF contact lens-induced simultaneous DF integration on electro-retinal activities. Methodology: All subjects underwent eye examinations and global flash multifocal electroretinogram (MOFO-mfERG) measurement. The primary and secondary outcomes were the mfERG response amplitude and its implicit time respectively. In Experiment 1, 30 myopic young adults (mean age: 23.1 ± 2.1 years) were recruited. MOFO-mfERG was measured for each subject wearing the contact lenses under three defocus conditions: single vision (in-focus) contact lens (control), +2.5D defocus incorporated DF contact lens and +7.5D defocus incorporated DF contact lens. In Experiment 2, 11 and 12 myopic young adults (mean ages: 23.6 ± 2.7 and 23.3 ± 2.7 years, respectively) were recruited for testing condition involving the wearing of +2.5D and +7.5D defocus incorporated DF contact lenses, respectively. The mfERG under the effects of these lenses was recorded at 30, 60 and 120 mins. Results: In Experiment 1, the amplitudes of MOFO-mfERG responses increased only in the para-macular region as the defocus power of the DF was induced. The direct component (DC) amplitudes increased significantly under the conditions of +2.5D (mean difference ± standard error: 2.62 ± 0.98 nV/deg2, p = 0.035) and +7.5D defocus (2.38 ± 0.92 nV/deg2, p = 0.045), compared to the control condition. The induced component (IC) amplitudes also increased significantly under the +7.5D defocus condition (4.06 ± 1.30 nV/deg2, p = 0.012). The defocus power had no effect on the implicit times of mfERG responses. In Experiment 2, the DC amplitude of MOFO-mfERG responses generally increased as the duration of the defocus condition increased. The amplitudes in the para-macular and peri-macular regions increased significantly from 30 to 120 min under both +7.5D (F2,22 = 3.817, p = 0.038) and +2.5D defocus (F2,20 = 8.232, p = 0.002). The DC implicit time in the central macular region under +7.5D defocus exhibited a marginal but significant increase (F2,20 = 3.441, p = 0.05) from 30 to 120 min. However, the IC response did not change over time under the DF condition. Conclusion: Both the outer (DC) and inner (IC) retinal activities in the para-macular region reacted strongly to different defocus powers during simultaneous DF integration induced by DF contact lenses. Additionally, temporal dose-response changes in the outer retinal activities were observed in the para- and peri-macular regions under simultaneous DF integration. Accordingly, simultaneous DF integration in terms of the defocus power and duration would modulate retinal activities at different levels. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5378.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 1.53 MB | Adobe PDF | View/Open |
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