COA - Certified Ophthalmic Assistant Visual Assessment and Testing Questions and Answers — Questions and Answers
Question 1: A patient's best-corrected distance visual acuity is 20/40 in the right eye. When you recheck the vision with a pinhole occluder, it improves to 20/25. What is the most likely cause of the reduced vision?
- Uncorrected refractive error (Correct answer)
- Cataract
- Macular degeneration
- Amblyopia
Correct answer: Uncorrected refractive error
The pinhole occluder works by blocking scattered light and allowing only focused central rays to reach the retina. This minimizes the effect of optical imperfections of the eye. An improvement in vision with the pinhole test strongly indicates that the reduced acuity is due to an uncorrected refractive error (like myopia, hyperopia, or astigmatism) that can be corrected with glasses or contact lenses. Vision loss from cataracts, macular disease, or amblyopia typically does not improve with a pinhole.
Question 2: When performing Amsler grid testing on a patient, which of the following instructions is most critical for an accurate result?
- "Hold the grid at a comfortable reading distance, about 12-14 inches away." (Correct answer)
- "Test both eyes together first, then check each eye individually."
- "Remove your reading glasses to avoid any distortion they might cause."
- "Focus on the entire grid at once to see the overall pattern."
Correct answer: "Hold the grid at a comfortable reading distance, about 12-14 inches away."
The Amsler grid is designed to test the central 20 degrees of the visual field at a specific distance. Holding the grid at a consistent reading distance (typically 12-14 inches or 30 cm) is essential for the test's standardization and accuracy. Testing must be done monocularly (one eye at a time) while wearing any near correction (reading glasses) the patient normally uses. The patient should fixate on the central dot, not scan the entire grid.
Question 3: A Certified Ophthalmic Assistant is performing confrontation visual field testing on a patient. The assistant and patient are seated facing each other. To properly test the patient's right eye, the assistant should instruct the patient to cover their left eye and the assistant should cover their:
- Left eye, looking at the patient's nose
- Right eye, looking at the patient's right eye (Correct answer)
- Left eye, looking at the patient's right eye
- Right eye, looking at the patient's left eye
Correct answer: Right eye, looking at the patient's right eye
Confrontation visual field testing compares the patient's peripheral vision to the examiner's. To test the patient's right eye, the patient covers their left eye. The examiner then covers their own right eye (the one directly opposite the patient's covered eye) and instructs the patient to look at the examiner's open (left) eye. This allows for a direct comparison of the temporal field of the patient's right eye and the nasal field of the examiner's left eye, and vice versa.
Question 4: Which of the following is the primary purpose of using Ishihara plates during a visual assessment?
- To measure intraocular pressure
- To assess stereopsis and depth perception
- To screen for red-green color vision deficiencies (Correct answer)
- To detect central visual field defects
Correct answer: To screen for red-green color vision deficiencies
The Ishihara test consists of a series of pseudoisochromatic plates, which are figures or numbers made of colored dots embedded in a background of differently colored dots. It is specifically designed as a screening tool to detect protanopia and deuteranopia, which are forms of red-green color vision deficiency.
Question 5: A 5-year-old child is being tested for stereopsis. Which of the following tests would be most appropriate for this age group?
- Amsler Grid
- Titmus Fly Test (Correct answer)
- Confrontation Fields
- Snellen Acuity Chart
Correct answer: Titmus Fly Test
The Titmus Fly Test is a common and effective method for evaluating stereopsis (depth perception), especially in children. It uses polarized glasses and features a large, three-dimensional fly, as well as animal figures and graded circles, which are engaging for young patients and do not require them to identify letters or numbers. The Amsler grid tests for central field defects, confrontation fields test peripheral vision, and the Snellen chart measures visual acuity.
Question 6: If a patient cannot see the largest letter on the Snellen chart (20/400), what is the next step in assessing their visual acuity?
- Record the vision as NLP (No Light Perception)
- Use the pinhole occluder
- Move the patient closer to the chart until they can see the largest letter
- Assess their ability to count fingers (CF) at a specified distance (Correct answer)
Correct answer: Assess their ability to count fingers (CF) at a specified distance
When a patient's vision is below the limit of the chart (e.g., less than 20/400), the visual assessment proceeds in a standardized sequence. The next step is to test if they can count the number of fingers the examiner holds up at a certain distance (e.g., CF at 3 feet). If they cannot count fingers, the next steps are to assess for hand motion (HM), and then light perception (LP). NLP is the final designation if the patient cannot perceive a bright light.
COA - Certified Ophthalmic Assistant Visual Assessment and Testing Questions and Answers
A patient's best-corrected distance visual acuity is 20/40 in the right eye.
When you recheck the vision with a pinhole occluder, it improves to 20/25.
What is the most likely cause of the reduced vision?