McGonigle_2016.pdf (7.48 MB)
Reading, contrast adaptation and accommodation in young adult myopes and emmetropes
thesis
posted on 2023-08-30, 15:09 authored by Colm McGonigleNumerous reports associate prolonged periods of near-work and specifically reading with
myopia development. The exact mechanisms that underpin this relationship are however,
unclear. Reading may induce perceptual adaptations, specifically changes in contrast
sensitivity and to the accuracy of the accommodation response. Reduced contrast
sensitivity and accommodation may degrade retinal image quality which could result in a
stimulus to ocular elongation and therefore myopia.
The experimental work undertaken in this thesis investigated whether reading text on a
screen influenced changes in contrast sensitivity (contrast adaptation) and accommodation
differently in young adult emmetropic and myopic participants. Contrast adaptation was
examined for spatial frequencies, including those created by text rows and character
strokes, and accommodative accuracy was determined before and after reading.
Furthermore, the influence of cognitive effort on such changes was explored by comparing
adaptation to an incomprehensible phase randomised stimulus that otherwise shared the
statistical properties of the text stimulus.
Reading text on a screen induced contrast adaptation at the spatial frequency created by
text rows and myopic participants incurred more than twice the adaptation of emmetropes.
Contrast adaptation was not significant at the spatial frequency created by character strokes
in either participant group. Myopic participants had significantly greater accommodative lag
(reduced accuracy) than emmetropes after reading text. Myopes also showed a significant
increase in accommodative lag after reading.
There was no significant change in contrast sensitivity or accommodative accuracy after
participants viewed the phased randomised stimulus.
Text stimuli are inherently dominated by low, narrowband and orientation constrained
spatial frequencies generated by row of letters and inter-row space. The results presented
show myopes to be more susceptible to adaptation to these specific text characteristics as
a consequence of active reading. However, there is extensive scope for further work to
determine precisely why this is the case and how such changes may engender myopia
development.
History
Institution
Anglia Ruskin UniversityFile version
- Accepted version
Language
- eng
Thesis name
- PhD
Thesis type
- Doctoral
Legacy posted date
2018-02-22Legacy creation date
2018-02-22Legacy Faculty/School/Department
Theses from Anglia Ruskin UniversityUsage metrics
Categories
No categories selectedLicence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC