Which statement best describes a similarity between the ETDRS and Bailey-Lovie charts?

Which statement best describes a similarity between the ETDRS and Bailey-Lovie charts?

• A. The progression of letter sizes is logarithmic
• B. They both use 4 letters per line
• C. They have no distance calibration
• D. They use a linear progression

Answer: (B)

The main idea here is that both charts are built to keep line difficulty consistent by using a fixed number of letters per line. This uniform line composition means every line represents the same amount of visual acuity change, so the overall score can be read off in equal, predictable steps. That consistency is what makes the two charts similar and easy to compare when measuring acuity. In practice, this design lets clinicians sum up the acuity from line to line without surprises—the progress from one line to the next corresponds to a standard logMAR increment. The other statements don’t fit as well: the size change is not a simple linear scale but a logarithmic one, both charts are distance-calibrated for standardized testing, and the increments are fixed rather than arbitrary.

The main idea here is that both charts are built to keep line difficulty consistent by using a fixed number of letters per line. This uniform line composition means every line represents the same amount of visual acuity change, so the overall score can be read off in equal, predictable steps. That consistency is what makes the two charts similar and easy to compare when measuring acuity.

In practice, this design lets clinicians sum up the acuity from line to line without surprises—the progress from one line to the next corresponds to a standard logMAR increment. The other statements don’t fit as well: the size change is not a simple linear scale but a logarithmic one, both charts are distance-calibrated for standardized testing, and the increments are fixed rather than arbitrary.