In a slit lamp examination, which slit width sequence and lighting angle are used?

• A. 5 mm then 3 mm; 0 degrees
• B. 2 mm then 1 mm; 45-60 degrees
• C. 1 mm then 0.5 mm; 30-40 degrees
• D. 3 mm then 2 mm; 15-30 degrees

Answer: (B)

Optimizing what you see with the slit lamp hinges on how the light is delivered. A narrow, well-placed beam provides better optical sectioning and edge definition, while the angle of illumination creates subtle shadows that reveal depth and tissue interfaces. The best approach here is to start with a moderate beam width of 2 mm to survey the structures, then narrow to 1 mm to scrutinize details more clearly. Pair that with oblique illumination around 45–60 degrees to maximize contrast and depth perception without glare. Angles that are too direct (0 degrees) or too shallow (15–30 degrees) reduce the usefulness of shadows and depth cues, and a beam kept too wide loses fine detail.