CPOA Clinical Procedures 2 — Questions and Answers
Question 1: When performing keratometry, which measurement is recorded?
- Intraocular pressure
- Corneal curvature (Correct answer)
- Pupil diameter
- Tear film break-up time
Correct answer: Corneal curvature
Keratometry measures the curvature of the anterior corneal surface, expressed in millimeters or diopters.
Question 2: A patient's visual acuity is recorded as 20/40. This means the patient sees at 20 feet what a person with normal vision sees at:
- 10 feet
- 20 feet
- 40 feet (Correct answer)
- 80 feet
Correct answer: 40 feet
The denominator in Snellen notation indicates the distance at which a person with normal vision can read the same line.
Question 3: Which instrument is used to measure intraocular pressure by applanation?
- Tonopen
- Goldmann tonometer (Correct answer)
- Schiotz tonometer
- Non-contact tonometer
Correct answer: Goldmann tonometer
The Goldmann applanation tonometer is the gold standard for measuring IOP by flattening a fixed area of the cornea.
Question 4: During lensometry, the optician neutralizes the lens power by aligning which targets?
- Mire rings
- The power drum circles
- Prism targets
- Sphere crosses and cylinder lines (Correct answer)
Correct answer: Sphere crosses and cylinder lines
In manual lensometry, the sphere is neutralized when the sphere crosses are clear, and cylinder is neutralized when the cylinder lines are clear.
Question 5: What is the purpose of instilling a topical anesthetic before Goldmann tonometry?
- To dilate the pupil
- To reduce patient discomfort and prevent blinking (Correct answer)
- To stain the tear film
- To lower IOP artificially
Correct answer: To reduce patient discomfort and prevent blinking
Topical anesthetics numb the cornea so the patient tolerates contact from the tonometer tip without reflexive blinking.
Question 6: A cover-uncover test is primarily used to detect:
- Refractive error
- Corneal opacity
- Strabismus (Correct answer)
- Retinal detachment
Correct answer: Strabismus
The cover-uncover test reveals a tropia (manifest deviation) by observing movement of the uncovered eye when the fellow eye is covered.
Question 7: When using a Burton lamp for contact lens evaluation, which light source is used?
- Infrared
- Ultraviolet (black light) (Correct answer)
- Halogen white light
- Coherent laser
Correct answer: Ultraviolet (black light)
A Burton lamp emits ultraviolet light, which causes sodium fluorescein dye on the cornea or contact lens to fluoresce.
CPOA Clinical Procedures 2
When performing keratometry, which measurement is recorded?