Which vision condition is characterized by a decreased ability to see contrast?

Macular degeneration is a vision condition that significantly impacts the ability to see contrast. This condition affects the macula, the central part of the retina responsible for sharp, detailed vision. In individuals with macular degeneration, the deterioration of the macula can lead to a reduction in the clarity of images and thereby diminish the ability to distinguish between different shades of light and dark. This impairment in contrast sensitivity can make it challenging for patients to perform tasks such as reading or recognizing faces, particularly in environments where the lighting is poor or the background is complex.

While the other options can affect vision in various ways, they do not primarily lead to a decreased ability to see contrast as macular degeneration does. Astigmatism causes distorted or blurred vision due to an irregularly shaped cornea, while night blindness refers to difficulty seeing in dim light, which is a different challenge than contrast sensitivity specifically. Color blindness impacts the perception of colors rather than contrast, focusing on the inability to distinguish between certain hues. Thus, macular degeneration is the correct answer as it directly relates to the decrease in contrast sensitivity.