Fig. 1

Schematic diagram of standard corneal densitometry analysis using Pentacam. Panel A: densitometry analysis of concentric annular zones centered at the corneal apex (a: 0–2 mm, b: 2–6 mm, c: 6–10 mm, d: 10–12 mm); Panel B corneal densitometry analysis based on different depths (anterior layer: inner 120 μm; center layer: from 120 μm to the last 60 μm; posterior layer: last 60 μm; total corneal thickness)