Before starting the biomicroscopic examination be familiar with the controls and adjustments.
Be sure the light source and biomicroscope are coincident.
With a slit light source on the focusing rod or patient's closed eye, be sure the slit is in the center of your field of view (slit must be in focus). The angle of the light source can be changed and sometimes it is left out of the "click" or alignment position. When this happens the slit is not in the center of your field. In this case rotate the slit back to the centered position (there is usually a click or locked position at the point where the slit should be centered).
