What is the primary output of volumetric OCT used for macular assessment?

• A. Optic nerve head contour analysis
• B. Thickness distribution map
• C. Color fundus photograph
• D. Fluorescein angiography

Answer: (B)

Volumetric OCT for the macula is analyzed most usefully through a thickness distribution map. The device collects a 3D data cube and then segments the retinal layers to measure how thick each region of the macula is. That thickness map, often color-coded, directly shows where the retina is thicker (as in edema) or thinner (as in atrophy) across the macula, and it can be compared to normal databases to spot abnormal patterns and monitor changes over time.

Other outputs exist, like detailed cross-sectional B-scans or en face views of reflectivity, but they don’t provide the quick, region-by-region thickness assessment that macular evaluation relies on. The optic nerve head contour focuses on the optic nerve area rather than the macula; a color fundus photograph is a 2D surface image of the retina; fluorescein angiography shows blood flow and leakage, not structural thickness.