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M MacKeben; Self-exploration Of The Visual Field After Central Vision Loss Is Enhanced By Kinesthetic Feedback . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3849.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To intensify and speed up learning of eccentric viewing after binocular central field loss. Methods: Two implementations were devised: The high-tech solution uses a personal computer with custom software and a lightpen. After mapping remaining vision in the macula by a macular mapping test (MMTest, San Francisco), the patient stabilizes gaze by fixating a high contrast angle profile on the screen. Its location is chosen to resemble the candidate quadrant with intact vision according to the mapping test. The field is explored by the patient’s hand moving the lightpen over the field subtended by the angle pattern. Where ever the patient points, a letter of variable size appears above the tip of the lightpen. Thus, the patient can judge in which position of his/her hand the target looks clearest. The low-tech solution uses a cardboard card with the same pattern and letters on small cards with a handle held by the patient. Both methods where used in random order by 34 patients with central scotomas due to a maculopathy. Results: The point with clearest vision was found by all patients using either method in less than 2 minutes. Comparing both methods, absolute locations of these points differed slightly, but the differences were statistically not significant (p≷0.5). Test-retest reliability was high (r≷0.9). The result later helps the patient to reverse the process and adjust gaze relative to a touched letter in a stable position, which is the first step towards using a Preferred Retinal Locus (PRL) for eccentric viewing. Equivalent conventional, examiner-driven methods without kinesthetic feedback proved to be at least 5 times more time-consuming. Conclusion: An inexpensive, easily implemented low-tech method providing patients with immediate kinesthetic feedback regarding hand (and target) position in the visual field can make the first step towards eccentric viewing faster and easier for the patient. A further advantage of the kinesthetic feedback method is that it is independent of verbal communication and can be applied at home.
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