Our vision is the sum of many parameters or aspects of vision, including but not limited to detail vision, contrast vision, surround vision, color vision, and dark adaptation. This module presents three aspects of vision with which we can describe quality of vision and functionality – detail vision, contrast vision, and surround vision – as well as some of the problems that are associated with these aspects of vision and potential solutions to these problems.
While doctors often focus on detail vision (visual acuity or sharpness) as a measure of vision, there’s more to vision than just that acuity number. Reduced contrast sensitivity, for example, can significantly affect vision quality, including affecting one’s acuity! Someone with low contrast sensitivity may have difficulty navigating his or her environment, even if they have good acuity. Disruptions to the visual field can affect one’s vision even with “good” acuity. In order to understand your current vision and implement solutions, it is invaluable to understand the many factors that affect how you are seeing.
For more than 100 years the measurement and description of a person’s vision has been tied to the results of the Snellen acuity test. But the letter chart test measures only visual acuity and measures it under almost ideal contrast conditions (deep black letters on an empty white background), an environment that does not represent the world we actively inhabit.
There’s much more to your vision than just your acuity number. In addition to detail vision, activities of daily living such as reading, cooking, using a computer, walking the streets and recognizing faces rely on visual components such as contrast vision, surround vision, color perception, stereoscopic acuity, dark adaptation, fixation and more.
Of these aspects of vision, the three most important are:
- Detail vision– the ability to see small details.
- Contrast vision – the ability to perceive small differences in brightness.
- Surround vision – the ability to respond to stimuli outside the area of central vision.