Akkommodaatiokyky

Akkommodaatiokyky, or accommodative ability, is the capacity of the eye’s lens system to change its curvature to focus light from objects at varying distances onto the retina. The process is mediated by the ciliary muscle, which relaxes when viewing distant objects and contracts when focusing on near items, allowing the crystalline lens to become more convex. Commonly measured in diopters, the accommodative amplitude is highest in children and gradually decreases with age, typically reaching zero by the late twenties.

Clinical assessment of akkommodaatiokyky involves several objective and subjective tests. The push‑up test and near‑point of accommodation test gauge the maximal accommodative response by having a patient focus on a target moved closer until blur appears. The negative‑lens test evaluates the ability to overcome added defocus, while dynamic retinoscopy and subjective refractive evaluation can quantify the amplitude in a more detailed manner. A normal adult is expected to have an amplitude of about 10–15 diopters, while a significant reduction may indicate presbyopia or accommodative disorders such as accommodative insufficiency, spasm, or paragonism.

The clinical importance of akkommodaatiokyky extends to prescription of reading glasses, contact lenses, and vision therapy. Low accommodative amplitude can interfere with near‑work performance and may require accommodative exercises or multifocal corrective lenses. Understanding and measuring the eye’s accommodative capacity remains essential for diagnosing refractive anomalies, planning surgical interventions such as multifocal intraocular lens implantation, and monitoring the progression of presbyopia.