On-line electro-oculography

A retinitis pigmentosa register for western Australia

This paper describes the main elements of the Western Australian retinitis pigmentosa register including details of the data stored on the register, aspects of the coding systems used and some description of the tests employed in diagnosis of retinitis pigmentosa. The register is family based and contains data on affected individuals and on their unaffected relatives. As at November 1991, the register contained data for 391 individuals from 207 separate families. Of the 391 individuals, 240 had definite or probable retinitis pigmentosa and 26 were possibly affected. The remainder were unaffected family members. In many cases, both affected and unaffected family members are being studied serially and the register is designed to store and easily retrieve serial data to allow study of disease progression for individuals and within families.

Analysis of saccadic eye movements with a microcomputer

This analysis of saccadic eye movements has found use in clinical diagnosis. Saccades are induced by a microcomputer-controlled TV stimulator and are recorded by electro-oculography. The analysis algorithm detects saccades by the velocity profile of eye position and then computes the principal saccadic parameters, peak velocity and amplitude. In addition, the saccades are presented on the VDU screen, together with the computed results of the analysis; they may be edited if necessary. The programs have been implemented in Pascal and Assembler languages.

A detailed study of sequential saccadic eye movements for normal- and poor-reading children

This paper presents the results of an in-depth study of parameters characterizing sequenced saccadic eye movements for a group of dyslexic children and a comparative normal control group with ages in the range greater than 8.0 yr. and less than 13.0 yr. No parameters were statistically different for the two groups, which supports the findings of Brown, et al. and contradicts the findings of Pavlidis. Our results indicate that sequenced saccadic eye movements are not diagnostically useful for early detection of dyslexia.

Smooth pursuit eye movements in normal and dyslexic children

This paper describes a detailed study of horizontal eye movements associated with visual tracking of a smoothly moving target. Essentially all children, even at target velocities as low as 5 degrees/sec., show some saccadic eye movements superimposed on smooth tracking movements. Detailed analysis of pursuit eye-movements from a group of 26 poor readers and 34 normal controls (8 to 13 yr.) showed that about 25% of poor readers have an abnormally raised saccadic component in smooth pursuit. This suggests that studies of eye movements during tracking of smoothly moving targets at low velocity, combined with a quantitative approach to data analysis, may be useful for early detection of a significant proportion of poor-reading children.

Dyslexia: saccadic eye movements

This paper describes an extensive study of the parameters of saccadic eye movement in a group of 28 poor-reading children and a comparative normally reading group of 31 children. Ages ranged from 6.0 to 16.9 yr. Poor readers had normal intelligence but were lagging by at least two years in reading ability as compared to their peer age group. Parameters studied in refixation eye movements included saccadic latency, accuracy, velocity, and acceleration, as well as differences in latency for abduct and adduct movements. Shapes of saccades were also studied. It was shown that eye-movement performance in simple saccadic refixation was not distinguishably different for poor readers and normal readers, even though in reading, which requires higher processing, eye-movement characteristics are quite different. Maturational changes for various saccadic eye-movement parameters were also examined for the normal and poor reading groups.

Eye movement analysis: reading and moving target pursuit

The design and application of an extensive and general software-based system for the study and analysis of eye movements in human subjects is described. The system can find application in a number of specialties in medicine, particularly clinical neurophysiology, as well as in studies of eye movement dynamics, including reading dynamics, in dyslexia. It is designed to run on the PDP 11 family of computers with standard peripherals and operating under the RT 11 executive.

Eye motion kinetics in moving target pursuit--a system for detection of oculomotor abnormalities in neurological disorders

An electrooculographic system for quantitive study of tracking eye motion is described. The tracking target is a projected spot of light which moves under computer control with different operator selectable constant accelerations. A single FORTRAN program with eleven subroutines, running on a PDP 11/40 computer in 22 K of memory, controls data collection and data analysis, as well as target movement. A number of quantitative parameters are extracted from the data, including smooth pursuit velocity, the correlation in movement between the two eyes and the maximum eye-target spot 'phase' difference in degrees. The relationship between smooth pursuit and saccadic eye movements can be visualised by storage and display of the instantaneous eye velocity during tracking manoeuvres. The system has proven very useful as an aid to diagnosis of some neurological disorders, particularly multiple sclerosis.

Effects of induced hyperthermia on visual evoked potentials and saccade parameters in normal subjects and multiple sclerosis patients

A convenient method for raising body temperature has been developed and used to evaluate temperature effects on visual evoked potentials and saccade reaction time and velocity in five normal subjects and five patients with multiple sclerosis.