ABSTRACT
The measurement of ERGs of infants and children suspected of having retinal dysfunction can present some significant practical problems. Often the degree of cooperation is less than ideal, the stimulus actually reaching the retina may vary, and the level of background electrical activity can mask small responses. Single flash ERGs often are not adequate in such circumstances, and usually it is advantageous to use some form of noise reduction. Conventional averaging techniques can be used, but one disadvantage is the time required to average a significant number of responses. The use of rapid, pseudorandomly timed stimuli and a cross-correlation signal recovery procedure offers some theoretical and practical advantages. Usually a better defined response (with a higher signal-to-noise ratio) can be obtained in a relatively short time, sometimes in a few seconds. In addition, the pseudorandomly timed flash stimuli inherently contain a wide range of frequencies, so that in effect the frequency response of the outer layers of the retina is being measured. Some clinical examples will be described to illustrate the practical application of this procedure for measuring the cone and rod ERGs of young patients.
Subject(s)
Electroretinography/methods , Retinal Diseases/diagnosis , Adolescent , Age Factors , Blindness/diagnosis , Child , Child, Preschool , Electroretinography/instrumentation , Esotropia/complications , Female , Humans , Infant , Male , Nystagmus, Pathologic/complications , Retinal Diseases/complications , Vision Disorders/diagnosisABSTRACT
A variation of "stripe therapy" for amblyopia was evaluated with the use of 50 amblyopic subjects. The stimulus consisted of a television game that had been modified to allow simultaneous display of the game and moving stripe patterns. Subjects used their amblyopic eye to play the game for 20 min/wk. Some of the subjects played the game with the super-imposed stripes, whereas a control group played the game without stripes. The exposure sessions continued for eight to 12 weeks, after which the subjects' visual acuities were measured for follow-up periods lasting up to a year. The visual acuities of many persons improved while they were playing the television game, but with wide variation in performance. During the six- to 12-month follow-up period, the visual acuities of patients decreased from the levels attained during the exposure period. There seemed to be no major difference between the results from persons exposed to stripes and those from the control group, either during the exposure sessions or during the follow-up period.
Subject(s)
Amblyopia/therapy , Photic Stimulation/methods , Television , Adolescent , Adult , Amblyopia/physiopathology , Child , Child, Preschool , Evaluation Studies as Topic , Humans , Patient Compliance , Visual AcuityABSTRACT
A variation of "stripe therapy" for amblyopia is described, using a composite video presentation of a television game with horizontal or vertical moving stripe backgrounds. The initial study has been carried out with two groups of amblyopic subjects, one group exposed to stripe backgrounds while playing the television games, and a small control group playing the games without any striped backgrounds. A wide range of results was obtained over several weekly exposure sessions, from possibly significant improvement to essentially no change in visual acuity. The results obtained from the group exposed to striped backgrounds do not appear to be markedly better than those obtained from the control group.
Subject(s)
Amblyopia/therapy , Orthoptics/methods , Television , Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Visual AcuityABSTRACT
Studies of the dynamic characteristics of horizontal saccadic eye motion give velocity, acceleration, and timing information. Average time differences between the motion of the eyes on left and right gaze, termed "differential delays," are statistical measures of the average differences of right-going and left-going velocity waveforms, and can be determined to within 0.5 msec. These relative time measurements give information that is not necessarily apparent from the velocity or acceleration data, and provide a sensitive measure of early oculomotor dysfunction. Patients with internuclear ophthalmoplegia have been shown to give characteristic abnormal values, and two such patients are described in detail to illustrate how these measurements may be used both to help in diagnosis and to characterize the presumed lesions.
Subject(s)
Eye Movements , Ophthalmoplegia/diagnosis , Adult , Female , Humans , Methods , Ophthalmoplegia/physiopathology , Time FactorsSubject(s)
Eye Movements , Acceleration , Adolescent , Adult , Aged , Child , Female , Fixation, Ocular , Humans , Male , Middle Aged , Time FactorsABSTRACT
A new procedure is described for cone electroretinography using a cross-correlation method of signal processing to give the response to flash stimuli which occur at randomly timed intervals. The output waveform is different than the usual repetitive flicker response, and can be presented on any desired time base. An unfamiliar aspect of this process is that most of the random time intervals between consecutive stimuli are shorter in duration than the output waveform. For the parameters described, the output waveform gives the response to approximately 1,640 stimuli in 65.5 sec., with a signal-to-noise ratio which is higher than that obtained when conventional averaging techniques are used over similar time periods. This allows more precise and statistically significant estimates to be made of the time and amplitude parameters of the cone response. Normal values are given for implicit (delay) time and amplitude, and examples are provided for comparison of the random flash response and conventional average electroretinograms (ERG's) in normal subjects and patients with retinal degeneration.