Lancaster test is used to evaluate the position of the eyes and eye movements. Investigation of horizontal and vertical deviations of eyes and cyclodeviations in pediatric and adult patients is possible. The direction and magnitude of deviation from the normal position of the eyes is easily detected using laser pointers. We usually investigate first the right eye and then the left eye.
The main difference between the Lancaster test and Hess screen is in the fact that in Hess screen we project a point and in Lancaster test we project a small line. So testing gets a third dimension.
The test kit of Lancaster test includes red and green laser pointers. Pointers project a line of about 20 centimetres on the screen at a distance of 1 m which has a size of 140 x 140 cm. Investigative grating printed on the screen, is not visible to the patient. In the course of testing red-green glasses are used.

Results

This instructional text about Hess screen and Lancaster test is intended for students and practitioners of optometry, orthoptics and ophthalmology. These tests are used to assess the proper function of eye muscles and are very important in determining the type of extraocular muscle dysfunction. In the first part of the publication we describe the properties of extraocular muscles including their origin, courses, insertion, innervation and function. The next parts are devoted to the particular test of ocular motility, including case studies.

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