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Dynamics in longitudinal eye movements and corneal shape
Author(s) -
Robert Iskander D.,
Kasprzak Henryk T.
Publication year - 2006
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.2006.00415.x
Subject(s) - curvature , radius of curvature , apex (geometry) , cornea , eye movement , radius , corneal topography , optics , context (archaeology) , lens (geology) , physics , mathematics , geology , geometry , ophthalmology , medicine , mean curvature , computer science , paleontology , computer security , mean curvature flow
The magnitude and character of longitudinal movements of the eye were studied in the context of high speed videokeratoscopy. It was of interest to determine whether these dynamic changes in the eye movements can affect the corneal shape and its estimation. A high speed videokeratoscope with a sampling frequency of 50 Hz was used for measuring the corneal apex movements as well as for measuring variations in the best‐fit sphere radius and central radius of curvature. The magnitude of the measured longitudinal apex movements could reach over 200 μ m showing a slow trend. The estimated local changes of the apex movements that could be associated with the cardiopulmonary system were about 40–50 μ m. The temporal variations in the equivalent estimated central radius of curvature ranged between 10 and 15 μ m. Spectral analysis of the longitudinal eye movements revealed strong signatures of the pulse and respiration signals as well as the assumed blink control signal. No clear association between the longitudinal apex movements and the corneal curvature was found. However, very slow significant changes in the corneal shape were observed. The central radius of curvature of the cornea revealed slow changes of up to 120 μ m. Understanding the nature of such changes will be of benefit in ophthalmic applications requiring highly accurate measurements of corneal shape, such as contact lens design and refractive surgery.