Visual Perimeter Measurement

Abstract

In one example of the invention a patient display is provided on which a fixation graphic or video is shown in substantially the centre of the display, and then target graphics or video are shown at different positions on the display about the centre. A test subject is positioned in front of the patient display at a known distance, and a camera captures an image of the test subject's eyes, to allow gaze direction determination to be performed. The captured images are displayed to a clinician user by a controlling test application, the clinician making a determination based on the images as to whether the test subject saw a target graphic or video when it was displayed. The clinician user then makes an appropriate input into the controlling test application, which also logs the position at which the target image was displayed. By displaying target graphics at multiple locations on the screen and logging the clinician inputs, the controlling test application is able to build up a plot of the peripheral vision field of the test subject. This plot can then be graphically displayed to the clinician user, and stored with the test results for future clinical use.

Description

TECHNICAL FIELD[0001]Examples of the present invention relate to a visual perimeter measurement system and method.BACKGROUND TO EXAMPLES OF THE INVENTION[0002]Accurate measurement of peripheral vision in a human can lead to early diagnosis of potentially serious medical conditions. Causes of visual field deficit include neonatal brain haemorrhage or stroke and eye conditions such as retinitis pigmentosa and glaucoma, additionally over 50% of childhood brain tumours present with visual impairment.[0003]A human eye converts light entering it into neural signals which are then sent down the optic nerve. Thus, the left optic nerve carries all of the visual information from the left eye, and the right optic nerve carries all of the visual information from the right eye. The optic nerves meet at the optic chiasm within the brain. Within the optic chiasm nerve fibres carrying visual information from the visual field temporal (lateral) to the vertical mid-line, cross to the other side. The ...

AI Technical Summary

Problems solved by technology

Such techniques are therefore difficult to use with small children, for example, because small children find the test extremely intimidating, and are unable to maintain visual fixation at the central point in accordance with the test instructions appropriately.

Similarly, elderly patients who may be suffering from degenerative brain diseases also present the same problems.

However, the system is extremely complicated, requiring much space, and equipment to set up.

In addition, the actual criterion by which it is judged whether a target has in fact been seen is open to error, as a decision is made purely based on whether the subject looks towards the direction of the target, but not whether in fact the target has been seen.

This method requires two clinicians, and the movement of the second clinician may be distracting, leading to an inaccurate test.

As such, this method is far from ideal, delivering a potentially poor result, as well as being costly to administer.

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