In a broad slit lamp biomicroscopy exam, what is the starting lamp arm position and viewing approach?

• A. Lamp arm at 0 degrees; view from front, back, and side to assess aqueous flare
• B. Lamp arm at 90 degrees; view from above
• C. Lamp arm at 45 degrees; view from the temporal side
• D. Lamp arm at 180 degrees; view from the posterior segment

Answer: (A)

Starting with the lamp arm at 0 degrees uses direct, straight-ahead illumination that gives you a broad, clear view of the anterior chamber. From this head-on position you can quickly assess the overall depth and clarity and establish a baseline. To detect aqueous flare, you then observe from multiple directions—front, back, and to the sides—while keeping the same starting illumination. The light is swept across the chamber so inflammatory cells and proteins in the aqueous can scatter light from different angles, making even subtle flare visible.

Other starting angles can still be useful later, but they don’t provide the best initial, comprehensive assessment of flare. Illumination from 90 degrees, 45 degrees, or from the posterior aspect isn’t as effective as a direct, multi-angle frontal view for revealing flare in a broad exam.