Premium
Comparison of high‐speed videokeratoscopy and ultrasound distance sensing for measuring the longitudinal corneal apex movements
Author(s) -
Kowalska Malgorzata A.,
Kasprzak Henryk T.,
Robert Iskander D.
Publication year - 2009
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.1475-1313.2009.00648.x
Subject(s) - apex (geometry) , context (archaeology) , coherence (philosophical gambling strategy) , eye movement , ultrasound , optics , computer science , computer vision , acoustics , artificial intelligence , medicine , physics , mathematics , anatomy , geology , statistics , paleontology
Abstract Two different methods to measure binocular longitudinal corneal apex movements were synchronously applied. High‐speed videokeratoscopy at a sampling frequency of 15 Hz and a custom‐designed ultrasound distance sensor at 100 Hz were used for the left and the right eye, respectively. Four healthy subjects participated in the study. Simultaneously, cardiac electric cycle (ECG) was registered for each subject at 100 Hz. Each measurement took 20 s. Subjects were asked to suppress blinking during the measurements. A rigid headrest and a bite‐bar were used to minimize undesirable head movements. Time, frequency and time‐frequency representations of the acquired signals were obtained to establish their temporal and spectral contents. Coherence analysis was used to estimate the correlation between the measured signals. The results showed close correlation between both corneal apex movements and the cardiopulmonary system. Unraveling these relationships could lead to better understanding of interactions between ocular biomechanics and vision. The advantages and disadvantages of the two methods in the context of measuring longitudinal movements of the corneal apex are outlined.