University of Iowa Health Care

Ophthalmology and Visual Sciences

Slit lamp examination

Richard C. Allen, MD, PhD, FACS
Additional Notes: Length 03:17

The Haag-Streit slit lamp is a relatively complex instrument with multiple knobs.  It is necessary to know what each of the knobs does, in order to become facile in the use of the instrument.  The knob inferior determines the width of the slit beam.  The top knob determines the vertical height of the slit beam.  The knob most superior determines the brightness and color of the slit beam.  The knob on the side with numbers determines the magnification of the image through the oculars.  Usually it is a good idea to start with a relatively low magnification and increase the magnification as needed.  There is space for a teaching scope, which is not on this slit lamp.  Pulling on the device superiorly will allow viewing through the teaching scope.  The oculars should be set at zero unless you are trying to correct your refractive error.  The oculars can be moved to accommodate your particular interpupillary distance.  The knob in front of the magnification is a stereo variator which can give or take away depth from the object that you are viewing.  The top portion of the slit lamp can be rotated to rotate the orientation of the slit beam from vertical to horizontal, essentially being able to rotate the beam 180 degrees.  The screw on the side will lock or lock the slit lamp so that it can move.  The patient should be adjusted for their height.  The knob on the left side of the slit lamp will move the chin rest up or down.  The black mark on the side should be in line with the patient's lateral canthus.

Performing an exam, the inferior palpebral and bulbar conjunctiva is examined.  The lateral, medial, and superior conjunctival surfaces are examined.  The cornea is then examined by narrowing the beam, followed by the anterior chamber structures.

At the conclusion of the exam, the screw on the side of the slit lamp should be tightened to lock the instrument into position. 

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See also the classic "Fundamentals of Slit Lamp Biomicroscopy" for a more detailed discussion (approximately 23 minutes).

December 19, 2016

last updated: 01/12/2017
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