Sehkraft

Sehkraft, in ophthalmology and optometry, describes the eye’s ability to resolve fine details at a given distance. It is commonly referred to as visual acuity and reflects the spatial resolution of the visual system. Clinically, the term is frequently used with best-corrected visual acuity (BCVA), which is measured after refraction and any necessary correction.

Measurement methods typically employ standardized optotype charts. The Snellen chart, read at a set distance (usually 5 meters or 20 feet), provides results as a Snellen fraction (for example, 20/20). Modern practice often uses decimal notation (for example, 1.0) or the logMAR scale, where 0.0 logMAR corresponds to 20/20. Visual acuity can be recorded for each eye (monocular) and for both eyes together (binocular). Near vision tests assess additional aspects of Sehkraft relevant to tasks such as reading.

Normal values and interpretation: a Sehkraft around 1.0 decimal (approximately 20/20 Snellen) is considered normal in many settings. Lower values indicate varying degrees of impairment; for instance, about 0.5 corresponds roughly to 20/40, and around 0.1 to 20/200. In many jurisdictions, best-corrected visual acuity of 20/200 or worse in the better eye is used as a benchmark for legal blindness, though definitions vary by country and criteria.

Factors and limitations: Sehkraft is influenced by refractive errors, media opacities (such as cataracts), ocular surface conditions, age, and neurological factors. Testing conditions—including distance, lighting, chart calibration, and patient cooperation—also affect results. Sehkraft is a key parameter in ophthalmic diagnosis, refractive planning, monitoring disease progression, and eligibility for activities such as driving.