Free CPO Keratometry and Corneal Topography Questions and Answers

Question 1

A keratometer is an instrument used to measure the:

Accepted Answer

Curvature of the central cornea

Answer

The keratometer, or ophthalmometer, is specifically designed to measure the curvature of the anterior surface of the cornea. These measurements, known as K-readings, are crucial for contact lens fitting and calculating the power of intraocular lenses for cataract surgery.

Question 2

In 'with-the-rule' astigmatism, the steepest corneal meridian is located at or near:

Accepted Answer

90 degrees (vertical)

Answer

'With-the-rule' astigmatism is the most common form, where the vertical meridian is steeper than the horizontal meridian. This is similar to the shape of a football lying on its side.

Question 3

What is the primary advantage of corneal topography over standard keratometry?

Accepted Answer

It provides a detailed map of the entire corneal surface.

Answer

While a keratometer measures only a few central points on the cornea, a corneal topographer maps the curvature of the entire corneal surface. This provides a much more detailed view, which is essential for detecting irregular astigmatism, keratoconus, and for planning refractive surgery.

Question 4

A patient's K-readings are 43.50 @ 180 / 45.00 @ 090. What is the amount of corneal astigmatism?

Accepted Answer

1.50 D

Answer

Corneal astigmatism is calculated by finding the difference between the two principal meridians. In this case, the difference between 45.00 D and 43.50 D is 1.50 D.

Question 5

On a standard corneal topography map, 'hot' colors such as red and orange typically represent areas that are:

Accepted Answer

Steeper in curvature

Answer

Topography maps use a color scale to represent corneal power, which is related to curvature. Hot colors (reds, oranges) indicate steeper areas with higher power, while cool colors (blues, greens) indicate flatter areas with lower power.

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Free CPO Keratometry and Corneal Topography Questions and Answers