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| Author | Subject: Hess Chart |
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 Kappa
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Hess Chart
May 09, 2006 23:56:20 What is the difference between a Hess chart and a Less screen? When would one be used over the other? Any advantages disadvanges of either of the two? Many Thanx |
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Stephen Meynell
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RE: Hess Chart
May 10, 2006 20:57:53 They both do the same job realy of measuring incomitancy. A one object for fixation method would be a using a torch and a cover to do a cover test in all 9 positions of gaze. The Hess Screen uses two fixation targets (a red torch held by practitioner and a green torch held by patient), one colored light for each eye and the patient wears a red filter over one eye and a green filter over the other. The Lees Screen uses two Hess Screens that are internally illuminated. They are set at right angles with a double sided mirror such that one screen is seen by one eye and the other screen is seen by the other when viewed via the mirror. The Hess Chart is a chart for recording the results - the lines of which are curved inwards to overcome perspective. -steve |