Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Faculty of Health and Social Sciences | en_US |
| dc.contributor.advisor | Chan, Henry (SO) | en_US |
| dc.creator | Fung, Man Yan Mavis | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/10894 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Effect of simultaneous dual-focus integration on electro-retinal activities in the human eye | en_US |
| dcterms.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. | en_US |
| dcterms.extent | xv, 112 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2019 | en_US |
| dcterms.educationalLevel | DHSc | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Contact lenses | en_US |
| dcterms.LCSH | Myopia -- Treatment | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | restricted access | en_US |
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 |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/10894