This question-specific review guide is tied to the answer reasoning for a PracticeTestVault item. Use it after you answer the question so the review stays focused on what the prompt actually tested.
What this question is testing
Objective: Effective power calculation
Prompt focus: A patient's lens power is measured as plus 10.00 diopters at a vertex distance of 12 millimeters. If the lens is moved closer to the eye, the effective power experienced by the eye will
Why the correct answer works
decrease, requiring a stronger lens to maintain the same correction
For a plus lens, moving it closer to the eye decreases the effective power, so a stronger lens is needed to maintain the correction.
Why the tempting wrong answer fails
Reducing the vertex distance of a plus lens does not turn it into a minus power.
Plain-language takeaway
For a plus lens, moving the lens closer to the eye reduces its effective power. To maintain the same correction at a shorter vertex distance, a stronger plus lens is required.
Simple analogy
Think of effective power calculation like following a short checklist: identify the clue, confirm the rule, and then make the move that fits this exact scenario.
How to review it before a retake
- Underline the command word and name what the question is asking before rereading the choices.
- Compare the correct answer against the closest distractor and write the exact detail that separates them.
- Retest this objective with a fresh question without looking at the rationale first.