Illinois Vision Certification Practice Test

Which error is considered a refractive error?

1. Glaucoma

2. Myopia

3. Cataract

4. Strabismus

The correct answer is: Myopia

Refractive errors are conditions where the shape of the eye prevents light from focusing directly on the retina, leading to blurry vision. Myopia, commonly known as nearsightedness, is one of the most prevalent refractive errors. In myopia, distant objects appear blurry because the light rays focus in front of the retina instead of directly on it. This condition occurs when the eyeball is too long or the cornea has too much curvature. In contrast, the other conditions listed do not fall under the category of refractive errors. Glaucoma is primarily a disease of the optic nerve often associated with increased intraocular pressure. Cataracts involve the clouding of the eye's lens, leading to blurry vision but not related to how light is refracted. Strabismus is a condition where the eyes do not properly align with each other, affecting coordination and not the refractive ability of the eye. Each of these conditions affects vision but does not specifically modify how light is refracted, which is the defining characteristic of refractive errors like myopia.