A quantitative analysis of eye movement characteristics during the cover test
type: CreativeWork
description: The cover test is probably the most widely used clinical test of oculomotor status. It is surprising therefore, that there has been only one previous study which has attempted to provide a quantitative analysis of the eye movements during the test. There is also a dearth of information concerning the relationship between eye movements during the cover test and symptomatology and the correlation between cover test results and the outcome of other tests of binocular function. For the investigations described in this thesis, apparatus was developed to provide precise measurements of eye movements during a computer-controlled cover test, with subjects fixating a distant (3.4m) and near (0.4m) target. In the first study, this apparatus was employed to assess a group of asymptomatic emmetropes aged between 18 and 35 years (n = 100). The pattern of eye movements recorded was more complex than is often assumed. Eye movements during dissociation followed various patterns, with some subjects reaching a position of equilibrium within a few seconds while 20% had not reached a stable position at the end of the 10 s occlusion period. It was concluded that the 'standard' procedure of occluding an eye during the cover test for only about 2s is not adequate. The mean phoria after 10 s occlusion was 0.000 for distance fixation and -1.38° (exo) for near fixation. The pattern of eye movements during the recovery phase consisted of a variety of saccadic and vergence movements. There was a statistical difference between exophores and esophores for frequencies of initiating saccades and vergence eye movements (p < 0.001) with esophores more commonly commencing recovery with a saccade and exophores with a vergence eye movement. Recovery movements were often associated with movements of the "fixating" eye. There was a poor correlation between phoria amplitude and recovery time. In the second study, the relationship between the nature of eye movements during the cover test and the results of…
abstract: The cover test is probably the most widely used clinical test of oculomotor status. It is surprising therefore, that there has been only one previous study which has attempted to provide a quantitative analysis of the eye movements during the test. There is also a dearth of information concerning the relationship between eye movements during the cover test and symptomatology and the correlation between cover test results and the outcome of other tests of binocular function. For the investigations described in this thesis, apparatus was developed to provide precise measurements of eye movements during a computer-controlled cover test, with subjects fixating a distant (3.4m) and near (0.4m) target. In the first study, this apparatus was employed to assess a group of asymptomatic emmetropes aged between 18 and 35 years (n = 100). The pattern of eye movements recorded was more complex than is often assumed. Eye movements during dissociation followed various patterns, with some subjects reaching a position of equilibrium within a few seconds while 20% had not reached a stable position at the end of the 10 s occlusion period. It was concluded that the 'standard' procedure of occluding an eye during the cover test for only about 2s is not adequate. The mean phoria after 10 s occlusion was 0.000 for distance fixation and -1.38° (exo) for near fixation. The pattern of eye movements during the recovery phase consisted of a variety of saccadic and vergence movements. There was a statistical difference between exophores and esophores for frequencies of initiating saccades and vergence eye movements (p < 0.001) with esophores more commonly commencing recovery with a saccade and exophores with a vergence eye movement. Recovery movements were often associated with movements of the "fixating" eye. There was a poor correlation between phoria amplitude and recovery time. In the second study, the relationship between the nature of eye movements during the cover test and the results of…
author: Barnard, N. A. S.
keywords: RE Ophthalmology
date published: 1999-07
date modified: 2026-07-24T01:39:20Z
provider: City University of London
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: City University London