Which anatomical landmark is used to start a measurement of the angle using anterior segment OCT?

Which anatomical landmark is used to start a measurement of the angle using anterior segment OCT?

• A. Scleral Spur
• B. Corneal apex
• C. Iris root
• D. Optic nerve head

Answer: (A)

The scleral spur is used as the starting landmark because it marks the boundary where the corneoscleral tissue transitions into the trabecular meshwork, providing a stable, repeatable reference for anterior segment angle measurements (such as AOD and TIA). From this spur, the angle recess is quantified toward the iris. The corneal apex, iris root, and optic nerve head are not fixed references for defining the angle boundary, so they aren’t appropriate starting points for these measurements.

The scleral spur is used as the starting landmark because it marks the boundary where the corneoscleral tissue transitions into the trabecular meshwork, providing a stable, repeatable reference for anterior segment angle measurements (such as AOD and TIA). From this spur, the angle recess is quantified toward the iris. The corneal apex, iris root, and optic nerve head are not fixed references for defining the angle boundary, so they aren’t appropriate starting points for these measurements.