kontrastisensitiivisyyttä

Kontrastisensitiivisyyttä, known in English as contrast sensitivity, refers to the ability of the visual system to detect differences in brightness or lightness between adjacent areas. It is a measure of how well an individual can perceive subtle variations in luminance. This visual function is crucial for everyday tasks such as reading, driving, and recognizing faces, especially in low light conditions or when there is glare.

Several factors can influence contrast sensitivity, including the overall lighting level, the size of the object being viewed, and the spatial frequency of the visual stimulus. For example, contrast sensitivity is typically better in well-lit environments than in dim light. Similarly, the visual system is more sensitive to larger objects than to very small ones. Spatial frequency relates to the level of detail in an image; low spatial frequencies correspond to coarse patterns, while high spatial frequencies represent fine details.

Impairments in contrast sensitivity can be caused by a variety of conditions, including cataracts, glaucoma, diabetic retinopathy, and neurological disorders affecting the visual pathways. Age-related changes can also lead to a decline in contrast sensitivity. Testing contrast sensitivity involves presenting the patient with a series of gratings or charts with varying levels of contrast and spatial frequency, and determining the lowest contrast level they can reliably detect at each frequency. This provides a more comprehensive assessment of visual function than standard visual acuity tests alone.