Corneal refractive changes due to short-term eyelid pressure in downward gaze
Shaw, Alyra J., Collins, Michael J., Davis, Brett A., & Carney, Leo G. (2008) Corneal refractive changes due to short-term eyelid pressure in downward gaze. Journal of Cataract and Refractive Surgery, 34(9), pp. 1546-1553.
Purpose: To assess corneal refractive changes after visual tasks of 15 minutes duration and their association with eyelid morphology.
Setting: Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia.
Methods: Eighteen young subjects with normal ocular health were recruited. Corneal topography was measured with a videokeratoscope prior to and after four conditions consisting of two downward gaze angles (20 degrees and 40 degrees) and two types of visual tasks (reading and steady fixation). Anterior eye photography in downward gaze was used to determine the eyelid angle, tilt and position with respect to the cornea.
Results: There were significant changes in corneal refractive power after the 15 minute downward gaze tasks. The largest group mean corneal sphero-cylindrical change was +0.33/-0.30x84 after reading in 40 degrees downward gaze (4 mm corneal diameter). The refractive changes after the 40 degrees tasks were significantly larger than the changes after the 20 degrees tasks (p<0.001). The changes in refractive RMSE were significant for all conditions, except the 20 degrees steady fixation task, for 4 and 6 mm analysis diameters (p<0.05). Significant correlations were found between some aspects of eyelid morphometry and corneal refractive change.
Conclusion: The pressure of the eyelids on the cornea in short-term downward gaze resulted in optically and clinically relevant corneal changes. Correlation between the refractive corneal changes and eyelid parameters suggests that the angle, shape and position of the eyelids influence the nature of the corneal changes. When high accuracy is required, refraction should be qualified in terms of the visual tasks undertaken prior to assessment.
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|Item Type:||Journal Article|
|Keywords:||corneal topography, eyelid pressure, near tasks|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2008 Elsevier|
|Copyright Statement:||Reproduced in accordance with the copyright policy of the publisher.|
|Deposited On:||07 Jul 2008 00:00|
|Last Modified:||29 Feb 2012 13:53|
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