Method and apparatus for determining magnocellular pathway defect and dyslexia

For a subject eye having a magnocellular pathway and a parvocellular pathway, apparatus for determining magnocellular pathway defects in the subject eye comprising:

• a series of patterns spatially varying in light intensity, each pattern providing a degree of contrast between areas of varying light intensity, and different patterns having different degrees of contrast between respective areas of varying light intensity, the degrees of contrast being between about 1% to about 50%;
• a response assembly for obtaining from the subject eye a magnocellular pathway response alone, the magnocellular pathway response being indicative of processing by the magnocellular pathway independent of processing by the parvocellular pathway, the response assembly including (i) display means for presenting to the subject eye the series of patterns at a sufficient stimulation frequency between about 0.5 Hz and 15 Hz such that the patterns serve as rapid low contrast stimuli to the eye for processing by the magnocellular pathway of the subject eye, and (ii) means for measuring, for each pattern, steady state response of the eye specific to the magnocellular pathway response of the eye, said measuring means providing magnocellular pathway signals indicative of processing by the magnocellular pathway of the eye independent of processing by the parvocellular pathway;
• and
• computer means coupled to the measuring means of the response assembly for receiving the magnocellular pathway signals from the measuring means, said computer means being responsive to the magnocellular pathway signals in a manner which relates the signal indicated responses to the corresponding patterns and plots the signal indicated responses against a predefined range of standard responses for the corresponding patterns, the predefined range of standard responses being from target subjects having non-defective magnocellular pathways, such that the computer means plots signal indicated responses outside of the predetermined range when there is a magnocellular pathway defect in the visual system of the subject eye, said plotting enabling a comparative graph of the signal indicated responses with respect to the predetermined range of standard responses to be output from the computer means.

A method of detecting dyslexia comprising the steps of:

• providing a series of temporally varying patterns of spatially varying light intensity, each pattern providing a certain degree of contrast between areas of varying light intensity and different patterns having different degrees of contrast between respective areas of varying light intensity, the degrees of contrast being in the range of about 1% to about 50%;
• providing a subject eye having a visual system comprising a magnocellular pathway and a parvocellular pathway;
• obtaining from the subject eye a magnocellular pathway signal alone, said signal being indicative of processing by the magnocellular pathway independent of processing by the parvocellular pathway, said obtaining the magnocellular pathway signal alone by (i) presenting to the subject eye the series of patterns at a sufficient stimulation frequency such that the patterns serve as rapid low contrast stimuli to the eye, and (ii) for each pattern, measuring response of the eye specific to the magnocellular pathway response of the eye, including obtaining a steady state visually evoked potential of the eye;
• and
• using computer means receiving the measured responses and plotting the measured responses against a predetermined range of normal responses to the series of patterns, the predetermined range of normal responses being from non-dyslexic target visual systems, said plotting providing measured responses outside of the predetermined range when there is a case of dyslexia, and said plotting enabling a comparative graph of the measured responses with respect to the predetermined range of normal responses to be output by the computer means for indicating a case of dyslexia.

Apparatus for determining dyslexia in a subject eye having a magnocellular pathway and a parvocellular pathway, the apparatus comprising:

• a series of temporally varying patterns of spatially varying light intensity, each pattern providing a certain degree of contrast between areas of varying light intensity, and different patterns having different degree of contrast between respective areas of varying light intensity, the degrees of contrast being between about 1% to about 50%;
• a response assembly for obtaining a magnocellular pathway response alone of the subject eye indicative of processing by the magnocellular pathway independent of the parvocellular pathway, the response assembly including (i) display means for presenting to the subject eye the series of patterns at a sufficient stimulation frequency between about 0.5 Hz and 15 Hz such that the patterns serve as rapid, low contrast stimuli to the eye, and (ii) for each pattern, means for measuring response of the eye specific to the magnocellular pathway response of the eye, including at least a steady state visually evoked potential of the eye, the means for measuring providing magnocellular pathway signals alone, said signals being indicative of the magnocellular pathway response of the eye independent of parvocellular pathway response of the eye;
• and
• computer means coupled to the measuring means and responsive to the magnocellular pathway signals from the measuring means in a manner which relates the signal indicated responses to the corresponding patterns and plots the signal indicated responses against a predefined range of normal responses for the corresponding patterns, the predefined range of normal responses being from non-dyslexic target subjects having non-defective magnocellular pathways, such that the computer means plots signal indicated responses outside of the predefined range in the case of dyslexia, and on output the computer means generates a comparative graph of the signal indicated responses with respect to the predefined range of normal responses, said graph indicating a case of dyslexia.