Certified Ophthalmic Assistant Practice Exam

How is the dioptric power of the cornea primarily determined?

1. Keratometer readings

2. Lensometry

3. Refraction tests

4. Fundus photography

The correct answer is: Keratometer readings

The dioptric power of the cornea is primarily determined through keratometer readings. A keratometer measures the curvature of the cornea and is able to quantify its refractive power by assessing the radius of curvature of the anterior surface. The curvature is directly related to the focusing ability of the cornea, which is the primary refractive component of the eye. In contrast, lensometry is used to measure the power of spectacle lenses, while refraction tests assess the overall refractive status of the eye including contributions from the cornea, lens, and other factors. Fundus photography captures images of the retina but does not provide direct measurements regarding corneal power. Therefore, the use of a keratometer specifically targets the assessment of corneal curvature, making it the primary method for determining the dioptric power of the cornea.