---
title: What is keratometry?
description: "Keratometry measures the curvature of the central cornea, providing information about its focusing power and astigmatism. It is a fundamental parameter in contact lens fitting and IOL calculations. ## Method Keratometers project mires onto the cornea and analyse their reflections…"
url: "https://bluefinvision.com/knowledge-base/topics/diagnostics-testing/what-is-keratometry/"
updated: "2025-12-11"
category: "Diagnostics & Testing"
---

# What is keratometry?

Keratometry measures the curvature of the central cornea, providing information about its focusing power and astigmatism. It is a fundamental parameter in contact lens fitting and IOL calculations.

## Method

Keratometers project mires onto the cornea and analyse their reflections to infer curvature in specific meridians. Many modern devices combine keratometry with topography or biometry.

- Outputs include corneal power in dioptres and axis of astigmatism
- Assumes a standard relationship between anterior curvature and total corneal power
- Readings are most accurate over a limited central zone
- Irregular corneas may require more advanced mapping techniques

## Clinical Role

Keratometry is essential in prescribing rigid contact lenses, calculating IOL power, and detecting significant corneal astigmatism. Changes over time may indicate corneal disease or effects of surgery.

- Baseline values help identify conditions such as keratoconus
- Regular measurements monitor corneal stability in refractive surgery candidates
- Errors in keratometry contribute directly to refractive surprises after surgery
- Results should be cross-checked with refraction and corneal imaging when needed