Contrast sensitivity

contrast sensitivity

Contrast sensitivity is the eye’s ability to detect differences in light and dark between an object and its background, especially when those differences are small. It measures how well you can see objects that do not stand out clearly, such as a gray car on a foggy morning or faint print on a page. This skill is different from sharpness of vision, which is usually tested by reading small letters on an eye chart; someone can have good sharpness but poor contrast sensitivity and still struggle in everyday situations. Tests for contrast sensitivity use patterns or letters at varying levels of contrast and size to find the lowest contrast you can reliably see. Many eye conditions — including aging changes, cataracts, glaucoma, and retinal disease — reduce contrast sensitivity before they affect standard visual acuity. Reduced contrast sensitivity also makes glare from headlights, bright sunlight, or oncoming street lamps more disabling. Because it affects practical tasks like driving at night, reading in dim light, recognizing faces, and moving safely in unfamiliar places, contrast sensitivity is a crucial measure of real-world vision. Treatments and strategies to help include better lighting, higher-contrast materials, anti-glare coatings, vision rehabilitation, and medical or nutritional approaches that support eye health. Detecting problems with contrast sensitivity early can prompt changes that improve daily functioning even when standard eye charts look normal. In short, contrast sensitivity tells us how well a person can see subtle differences in brightness that are essential for safe, comfortable vision in many everyday situations.