ABO Low Vision & Rehabilitation 2

Question 1

Which magnification formula correctly calculates the required add power for a patient with 20/200 acuity who wants to read standard newsprint (20/40 equivalent)?

Accepted Answer

Add = (20/200) / (20/40) × 4D = 20D

Answer

The required magnification is 200/40 = 5×, and since 1× requires approximately 4D, the needed add is 5 × 4D = 20D.

Question 2

A patient with central scotoma due to macular degeneration is taught eccentric viewing. The preferred retinal locus (PRL) is most commonly located in which direction relative to the scotoma?

Accepted Answer

The PRL location varies by individual and must be determined clinically

Answer

The PRL develops spontaneously in a location that varies among individuals, and clinical assessment (e.g., microperimetry or scanning laser ophthalmoscopy) is needed to identify it.

Question 3

Which illumination strategy is most beneficial for a patient with retinitis pigmentosa (RP) experiencing significant glare sensitivity indoors?

Accepted Answer

Use highly directional task lighting aimed at the work surface while reducing ambient light

Answer

Directing task lighting onto the work area while keeping ambient lighting lower reduces the glare-contrast problem common in RP patients with rod depletion.

Question 4

A 68-year-old patient's best-corrected visual acuity is 20/400. When fitting a spectacle-mounted telescope for distance mobility, the clinician should prioritize which consideration?

Accepted Answer

Field of view, weight, and cosmetic acceptance in addition to acuity improvement

Answer

High-magnification telescopes drastically reduce field of view and are heavier, so functional factors and patient acceptance must be balanced with acuity improvement.

Question 5

Stand magnifiers are optically designed so that the image they produce is located at which focal distance?

Accepted Answer

At infinity, requiring no additional accommodation or add

Answer

A stand magnifier places the object at its focal point, producing a virtual image at optical infinity that requires no accommodation (or only the patient's habitual near add) to view.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Low Vision & Rehabilitation 2