Which condition is defined as reduced visual acuity not correctable by refractive means?

• A. Presbyopia
• B. Hyperopia
• C. Amblyopia
• D. Aphakia

Answer: (C)

Amblyopia occurs when reduced visual acuity cannot be improved with glasses or other refractive correction because the issue lies in how the brain processes visual input, not in the eye’s optics. It typically develops in childhood when one eye provides a poorer image due to misalignment (strabismus), unequal refractive error (anisometropia), or deprivation from obstruction. The brain starts to ignore or suppress the weaker eye to avoid confusion, so vision remains reduced even though the eye could be optically corrected. Early detection and treatment—such as addressing the underlying cause and sometimes using occlusion therapy—can improve vision if caught during the critical period of visual development. This contrasts with presbyopia (age-related near vision improved with reading glasses), hyperopia (farsightedness corrected with lenses), and aphakia (absence of the lens, managed with corrective lenses or implants), all of which can be corrected optically.