Refraktiotesti

Refraktiotesti is a diagnostic procedure used to determine the refractive status of the eye and to prescribe corrective lenses. In ophthalmology and optometry it is a standard part of a comprehensive eye examination, aimed at identifying refractive errors such as myopia, hyperopia, and astigmatism, as well as presbyopia. It may also be used in planning refractive surgery and in monitoring changes in vision over time.

The test uses both objective and subjective methods. Objective refraction employs instruments such as an autorefractor or a retinoscope to estimate the eye’s refractive power without relying on patient responses. Subjective refraction relies on the patient’s feedback while the clinician presents a series of lenses in a phoropter to determine the best correction. Results are expressed in diopters and specify sphere, cylinder, and axis, with an additional near addition when needed. In children or when accommodation is a factor, cycloplegic refraction may be performed to obtain an accurate measurement.

During the procedure, distance vision is typically tested with the patient looking at distant targets, and near vision is assessed as appropriate. The test is often complemented by keratometry, which measures corneal curvature, and may be combined with biometry when planning surgeries such as LASIK or cataract procedures. The final prescription may include glasses, contact lenses, or referrals for further testing.

Limitations include the influence of accommodation, lighting, fatigue, and contact lens wear. Refraction alone does not diagnose eye disease; comprehensive assessment of ocular health, retina, and optic nerve requires additional tests. Related terms include refractive error, myopia, hyperopia, and astigmatism, while refraktometry in non-medical contexts refers to measuring refractive indices of materials.