Certified Ophthalmic Assistant Practice Exam

What test can differentiate visual loss caused by refractive errors from that caused by eye diseases?

1. Pinhole disc

2. Visual field test

3. Color vision test

4. Contrast sensitivity test

The correct answer is: Pinhole disc

The pinhole disc is an effective tool for differentiating between visual loss due to refractive errors and that resulting from eye diseases. When patients experience blurred vision, placing a pinhole disc in front of their eyes allows them to focus light rays more precisely onto the retina. This often improves vision, indicating that the visual loss is likely due to a refractive error, such as nearsightedness or farsightedness. If the vision does not improve with the pinhole, it suggests that the issue may stem from an eye disease, as conditions such as cataracts, retinal detachment, or other pathologies could be responsible for the visual impairment. Other tests serve different purposes; for example, the visual field test assesses peripheral vision and can indicate problems with the optic nerve or visual pathways related to certain diseases rather than refractive issues. The color vision test evaluates the ability to perceive colors and does not inform about refractive conditions or overall visual acuity. Contrast sensitivity tests measure the ability to discern objects against varying backgrounds but are not designed specifically to differentiate between refractive errors and disease-related vision loss. Thus, the pinhole disc stands out as the optimal choice for this purpose.