COT Low Vision and Optical Aids 1 — Questions and Answers
Question 1: Which statement best defines 'low vision' as used in clinical ophthalmic practice?
- Visual acuity of 20/40 or better in the better eye with standard correction
- Visual acuity of 20/70 or worse in the better eye that cannot be corrected to normal with conventional lenses (Correct answer)
- Any degree of vision loss that requires reading glasses
- Complete absence of light perception in both eyes
Correct answer: Visual acuity of 20/70 or worse in the better eye that cannot be corrected to normal with conventional lenses
Low vision is defined as best-corrected visual acuity of 20/70 or worse in the better eye that cannot be improved to normal with standard spectacle correction.
Question 2: What is the leading cause of low vision in adults over 65 years of age in the United States?
- Diabetic retinopathy
- Open-angle glaucoma
- Age-related macular degeneration (Correct answer)
- Cataract
Correct answer: Age-related macular degeneration
Age-related macular degeneration (AMD) is the leading cause of low vision and legal blindness in Americans over age 65.
Question 3: Using the Kestenbaum rule, what reading add should be prescribed for a patient with a best-corrected distance acuity of 20/200?
- +2.00 D
- +5.00 D
- +10.00 D (Correct answer)
- +20.00 D
Correct answer: +10.00 D
The Kestenbaum rule prescribes an add equal to the denominator divided by the numerator of the Snellen fraction: 200 ÷ 20 = +10.00 D.
Question 4: Which technique involves training a patient with a central scotoma to use a peripheral retinal area for fixation?
- Binocular rivalry suppression
- Eccentric viewing (Correct answer)
- Contrast enhancement
- Reverse telescopy
Correct answer: Eccentric viewing
Eccentric viewing is a rehabilitation technique that teaches patients to shift fixation to a preferred retinal locus (PRL) outside the damaged fovea.
Question 5: Which type of magnification is achieved simply by moving an object closer to the patient's eye, without using any optical device?
- Angular magnification
- Projection magnification
- Relative distance magnification (Correct answer)
- Transverse magnification
Correct answer: Relative distance magnification
Relative distance magnification results from decreasing the viewing distance, which enlarges the retinal image without requiring any optical device.
Question 6: A stand magnifier held at or within its focal length produces an image that is:
- Virtual, erect, and magnified (Correct answer)
- Real, inverted, and magnified
- Virtual, inverted, and minified
- Real, erect, and minified
Correct answer: Virtual, erect, and magnified
When an object is placed at or within the focal length of a converging lens (as in a stand magnifier), the resulting image is virtual, erect, and magnified.
Question 7: Legal blindness in the United States is defined as best-corrected visual acuity in the better eye of:
- 20/40 or worse
- 20/70 or worse
- 20/200 or worse (Correct answer)
- 20/400 or worse
Correct answer: 20/200 or worse
Legal blindness in the US is defined as best-corrected visual acuity of 20/200 or worse in the better eye, or a visual field of 20 degrees or less.
COT Low Vision and Optical Aids 1
Which statement best defines 'low vision' as used in clinical ophthalmic practice?