COT Low Vision and Optical Aids 5

Question 1

Which of the following is a key advantage of an electronic magnification device (CCTV/video magnifier) over optical magnifiers for a patient with severe low vision?

Accepted Answer

Ability to adjust contrast and reverse polarity

Answer

Electronic video magnifiers allow users to adjust magnification, brightness, contrast, and reverse polarity (white-on-black), which optical magnifiers cannot provide.

Question 2

A patient with hemianopia (half-field loss) would MOST benefit from which type of low vision device to expand their visual field awareness?

Accepted Answer

Prism or mirror systems

Answer

Fresnel prisms, sector prisms, or mirror systems are used to shift or expand the field of view for patients with hemianopia, allowing them to detect objects in their blind hemifield.

Question 3

The illumination recommendation for most low vision patients engaged in near tasks is:

Accepted Answer

Bright, directed task lighting from the side or over the shoulder

Answer

Most low vision patients benefit from high-intensity, directional task lighting positioned to illuminate the work without causing direct glare in the patient's eyes.

Question 4

When a low vision patient uses a microscopic (high-plus) reading lens of +20D, what is the expected working distance?

Accepted Answer

5 cm

Answer

A +20D lens has a focal length of 1/20 = 0.05 m (5 cm), so the patient must hold reading material at approximately 5 cm from the lens to maintain focus.

Question 5

A COT is instructing a low vision patient on the use of a new optical aid. Which rehabilitation principle is MOST important to address first?

Accepted Answer

Establishing and training the patient's preferred retinal locus (PRL)

Answer

Before optimizing optical aids, identifying and training the patient to use their PRL consistently improves the effectiveness of any low vision device and is a foundational rehabilitation step.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Low Vision and Optical Aids 5