Keratometry readings are primarily used to assess curvature of which part of the eye?

• A. Central cornea area approximately 3 mm in diameter
• B. Scleral curvature
• C. Posterior cornea curvature
• D. Entire cornea surface

Answer: (A)

Keratometry measures the curvature of the anterior, central surface of the cornea. The central area about 3 mm in diameter is used because this region provides the most consistent, vision-critical curvature and largely determines the eye’s refractive power. By capturing curvature in two principal meridians, keratometry yields the corneal dioptric power and the amount and axis of corneal astigmatism, data that are essential for fitting contact lenses and for calculating intraocular lens or lens power. It does not assess scleral curvature, posterior corneal curvature, or the entire corneal surface, since those require other tests or more comprehensive corneal mapping.