Which astigmatism is measured by the surface of the cornea using a keratometer?

Which astigmatism is measured by the surface of the cornea using a keratometer?

• A. Regular astigmatism
• B. Corneal astigmatism
• C. Irregular astigmatism
• D. Oblique astigmatism

Answer: (B)

The correct answer is corneal astigmatism. This type of astigmatism arises from the shape and curvature of the cornea, which is the clear front surface of the eye. A keratometer is specifically designed to measure the curvature of the cornea, providing information on how light is refracted as it enters the eye. This measurement is crucial for understanding how the cornea's shape contributes to visual distortion, typical in corneal astigmatism. Regular and irregular astigmatism refer to the pattern of the light distortion and how the curvature varies in different meridians. While regular astigmatism can occur in both the cornea and the lens and may be identified using a keratometer, corneal astigmatism specifically emphasizes the cornea's measurements. Oblique astigmatism describes the orientation of the principal meridians rather than the characteristics measured by a keratometer. Hence, corneal astigmatism is the most accurate descriptor for what a keratometer assesses as it directly relates to the corneal surface measurements.

The correct answer is corneal astigmatism. This type of astigmatism arises from the shape and curvature of the cornea, which is the clear front surface of the eye. A keratometer is specifically designed to measure the curvature of the cornea, providing information on how light is refracted as it enters the eye. This measurement is crucial for understanding how the cornea's shape contributes to visual distortion, typical in corneal astigmatism.

Regular and irregular astigmatism refer to the pattern of the light distortion and how the curvature varies in different meridians. While regular astigmatism can occur in both the cornea and the lens and may be identified using a keratometer, corneal astigmatism specifically emphasizes the cornea's measurements. Oblique astigmatism describes the orientation of the principal meridians rather than the characteristics measured by a keratometer. Hence, corneal astigmatism is the most accurate descriptor for what a keratometer assesses as it directly relates to the corneal surface measurements.