Corneal topography using Placido disk technology measures which of the following optical parameters?
- A Anterior corneal curvature only ✓
- B Full corneal thickness (pachymetry)
- C Both anterior and posterior corneal curvature
- D Corneal epithelial thickness map
Correct answer: A. Anterior corneal curvature only
Explanation
Traditional Placido disk-based corneal topography (e.g., Orbscan in reflection mode) measures only anterior corneal surface curvature by analyzing the reflected mire images. It does not measure posterior corneal curvature or corneal thickness; these require Scheimpflug imaging (Pentacam) or slit-scanning technology. This is a critical distinction when screening for keratoconus, where posterior surface changes may precede detectable anterior surface changes.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.