Welch Allyn 18200 Bedienungsanleitung Seite 3

Introduction
Retinoscopy is a technique for objective refraction of the eye. There
are two basic types of retinoscopy. Static retinoscopy (described in
this booklet) is done with the patient fixating at a distance. Dynamic
retinoscopy is done with the patient fixating at a near target. These
techniques require diligence and expertise that can result in a
precise measurement of the refractive error of an eye.
There are two types of self-illuminated retinoscopes. The streak
retinoscope featured in this booklet is the most widely used
scope today and has largely supplanted the spot retinoscope. In
retinoscopy, a parallel or slightly divergent beam of light is directed
into the patient's eye. This results in illumination of the retina, and
the reflected light from the retina causes reflexes observed by the
examiner in the patient's pupil. The refractive status of the eye is
found by using correcting trial lenses to make the far point of the
ametropic eye conjugate to the pupil of the examiner's eye. When this
is achieved, the movement of the reflex will be neutralized.
The material in the booklet is presented with the assumption that
the reader is familiar with retinoscopy in general. Two excellent
references for retinoscopic technique are:
Corboy, J.M.; The Retinoscopy Book, 3rd Edition, 1989, SLACK Incorporated.
or on videotape: Guyton, D.L.; Retinoscopy: Minus Cylinder Technique or
Retinoscopy: Plus Cylinder Technique, 1986, American Academy of
Ophthalmology—Continuing Ophthalmic Video Education.
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