Contrast sensitivity refers to the ability to detect differences in light and dark areas, allowing us to perceive shapes and objects in various lighting conditions. It is crucial for everyday activities, such as driving at night or recognizing faces in dim environments. Unlike visual acuity, which measures sharpness, contrast sensitivity focuses on how well we can distinguish objects from their background. This ability can be affected by various factors, including age, eye health, and certain medical conditions like cataracts or glaucoma. Tests for contrast sensitivity often involve identifying patterns or letters against different backgrounds, helping to assess overall visual function and quality of life.