Keratometer Reading, Uses, Types, Parts, Price, Principle

A keratometer, also known as an ophthalmometer, is a diagnostic instrument used to measure the curvature of the anterior surface of the cornea, the transparent dome at the front of the eye. This measurement is important for diagnosing and correcting refractive errors such as nearsightedness, farsightedness, and astigmatism.

Keratometer Reading

The readings of a keratometer are typically represented by two numbers and an angle, like this:

43.00 D @ 180° (OD)
42.75 D @ 90° (OS)

• The first number (e.g., 43.00 D) represents the corneal curvature in one meridian, measured in diopters (D). A diopter is a unit of measurement for the refractive power of a lens. The higher the number, the steeper the curvature of the cornea in that meridian.
• The second number (e.g., 180°) represents the corneal axis in that meridian, measured in degrees. The corneal axis is the direction of the steepest curvature.
• The letters "OD" and "OS" refer to the right eye (oculus dexter) and left eye (oculus sinister), respectively.

Parts of a Keratometer

• Mire: A small illuminated target that is projected onto the cornea.
• Objective lens: Focuses the mire onto the cornea.
• Measuring telescope: Measures the size and position of the mire's reflected image.
• Base: Supports the instrument and positions it in front of the patient's eye.

Principle of Operation

The keratometer works by projecting a mire onto the cornea. The cornea acts like a convex mirror, reflecting the mire and creating an image. The curvature of the cornea determines the size and position of the reflected image. The keratometer measures these parameters and uses them to calculate the curvature of the cornea.

Types of Keratometer

There are two main types of keratometers:

• Manual keratometers: These require the operator to manually take measurements and make calculations.
• Automated keratometers: These use computers to automatically take measurements and generate results.

Uses of Keratometer

Keratometers are used for a variety of purposes, including:

Diagnosing and correcting refractive errors: The curvature of the cornea is a major factor in determining a person's refractive error. Keratometers can be used to measure the curvature of the cornea and help determine the appropriate corrective lenses.

Fitting contact lenses: The curvature of the cornea also affects how well contact lenses fit. Keratometers can be used to measure the curvature of the cornea and help ensure that contact lenses fit properly.

Monitoring for keratoconus: Keratoconus is a condition that causes the cornea to thin and bulge outward. Keratometers can be used to monitor the progression of keratoconus and help determine if treatment is necessary.

Planning for refractive surgery: Refractive surgery, such as LASIK, can be used to correct refractive errors. Keratometers are used to measure the curvature of the cornea before and after surgery.

Keratometer Price

Keratometer prices vary depending on type (manual: $500-$2,000, automated: $2,000-$10,000), brand, and seller. Consider your needs and budget while comparing prices from different sources.