COT Tonometry and Keratometry 2

Question 1

Which tonometry method uses a variable force to flatten a fixed area of cornea (3.06 mm diameter)?

Accepted Answer

Goldmann applanation tonometry

Answer

Goldmann applanation tonometry flattens a fixed 3.06 mm diameter corneal area and varies the force to achieve that area.

Question 2

What fluorescein pattern indicates the correct endpoint during Goldmann applanation tonometry?

Accepted Answer

Two semicircles whose inner edges just touch

Answer

The correct endpoint is when the inner edges of the two fluorescein-stained semicircles just touch each other.

Question 3

A patient has a central corneal thickness of 620 µm. How does this affect Goldmann IOP readings compared to a 545 µm cornea?

Accepted Answer

IOP reading is falsely high

Answer

Thicker corneas resist applanation more, causing the Goldmann tonometer to overestimate true IOP.

Question 4

During keratometry, what does the technician measure when aligning the plus (+) and minus (−) mires?

Accepted Answer

The radius of curvature of the anterior cornea in two principal meridians

Answer

Keratometry measures the radius of curvature of the anterior corneal surface in the flattest and steepest meridians.

Question 5

A keratometry reading of 44.00 D @ 90° / 46.00 D @ 180° indicates:

Accepted Answer

Against-the-rule astigmatism

Answer

Against-the-rule astigmatism exists when the steeper meridian is closer to horizontal (180°), meaning more power at 180° than 90°.

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