Autorefraktometer

An autorefraktometer, or autorefractor, is a diagnostic instrument used in optometry and ophthalmology to measure a patient’s refractive error objectively, without requiring active collaboration from the patient. The device projects light into the eye and analyzes the reflected image from the retina or retinal reflex to estimate the eye’s optical power. It typically reports spherical (SPH), cylindrical (CYL) and axis (AXIS) values, and may also provide a spherical equivalent. Modern instruments can include wavefront analysis to describe higher-order aberrations.

Autorefractors come in table-mounted and handheld forms. To obtain a measurement, the patient fixates on a target while the device aligns with the eye. Measurements can be affected by accommodation, fixation stability, pupil size, and media clarity, and cycloplegia may be used for accurate assessment in children or when accommodation is a concern. Some devices also integrate keratometry and offer estimates suitable for rapid screening or preoperative planning.

Common uses include routine vision screening, initial prescription of glasses or contact lenses, and preoperative assessment for cataract surgery. In routine care, autorefractor readings are usually refined with subjective refraction by a clinician to determine final prescription.

Limitations include device variability, potential inaccuracies in uncooperative patients, very young children, significant media opacities, or abnormal corneal shapes. Autorefractors are often complemented by other methods, such as retinoscopy or wavefront-based aberrometry, to ensure accurate refractive correction.