Minus lens to blur testing yields lower amplitudes than push-up because minus lenses cause what effect?

Minus lens to blur testing yields lower amplitudes than push-up because minus lenses cause what effect?

• A. Spectacle minification
• B. Increased magnification
• C. Lateral aberrations
• D. Increased pupil size

Answer: (A)

Minus lenses make the image you see through them smaller, a phenomenon known as spectacle minification. Tests that measure how far you can push your accommodation or how much vergence you can sustain rely on how large or how near the target appears to the eye. When you blur with minus lenses, the target’s retinal image shrinks, so it looks smaller and effectively farther away. That reduced apparent size and distance lowers the stimulus to accommodate and converge, leading to a lower measured amplitude than when you use the push‑up method, where the target physically grows and moves closer, increasing the stimulus and the measured amplitude. Increased magnification would do the opposite, and lateral aberrations or pupil size aren’t the primary factors driving this difference.

Minus lenses make the image you see through them smaller, a phenomenon known as spectacle minification. Tests that measure how far you can push your accommodation or how much vergence you can sustain rely on how large or how near the target appears to the eye. When you blur with minus lenses, the target’s retinal image shrinks, so it looks smaller and effectively farther away. That reduced apparent size and distance lowers the stimulus to accommodate and converge, leading to a lower measured amplitude than when you use the push‑up method, where the target physically grows and moves closer, increasing the stimulus and the measured amplitude. Increased magnification would do the opposite, and lateral aberrations or pupil size aren’t the primary factors driving this difference.