Certified Ophthalmic Medical Technologist (COMT) Practice Exam

In a case where a 4-year-old child has poor vision not improved by pinhole testing, what is the most likely cause?

1. Refractive error

2. Ametropic or isometropic amblyopia

3. Strabismus

4. Retinal detachment

The correct answer is: Ametropic or isometropic amblyopia

The scenario described—a 4-year-old child with poor vision that is not improved by pinhole testing—strongly indicates the presence of amblyopia, specifically ametropic or isometropic amblyopia. Pinhole testing helps to determine if the vision loss is due to a refractive error. If the child’s vision does not improve with this test, which eliminates the effects of refractive errors by allowing only light rays that are focused correctly to reach the retina, it suggests that the vision issue is not simply due to a refractive problem like myopia or hyperopia. Ametropic amblyopia occurs when there is significant uncorrected refractive error in one or both eyes, leading to the brain favoring one eye over the other. Isometropic amblyopia refers to equal refractive errors in both eyes yet still results in poor visual acuity due to the blurred images the brain receives. Since both situations can result in the brain not processing visual information properly, making pinhole testing ineffective, they are the most likely causes. Understanding amblyopia is crucial because early detection and treatment are vital for preventing long-term visual impairment. In this case, addressing amblyopia would be the primary concern, rather than other causes such