Decreases in contrast sensitivity and altered color perception can occur as a result from many eye conditions, such as glaucoma, diabetic retinopathy, cataracts, and macular degeneration to name a few, as well as some congenital eye diseases. Contrast sensitivity plays an important role in helping distinguish an object from its background.

How Contrast Sensitivity Impacts our Daily Life

If we wake up early in the morning before dawn, we may find ourselves fumbling in a dark room while trying to locate our slippers. How much easier is it to navigate the world once we turn on the lights in the room. Good lighting plays an integral part in reading the local newspaper, being able to navigate safely down a flight of stairs, and interact with objects in our environment with ease, from grabbing the handle of our coffee cup to locating a handle to pull open a drawer.

It’s Not Always About Having More Light

We see color as a result of light that is bounced from an object into the eyes. When there is more light available, more light is bounced from objects. Certain materials bounce light more than others as evident when looking at light reflected from metal versus wood. While being in a pitch dark room makes it hard to identify objects, more light may not always be effective. Think about the ease at which it is to drive during a bright sunny day versus a rainy day or at dusk when the sun is setting.
As seen in the above picture on the left, excess light bouncing off from objects and background can lead to a bleaching out effect, commonly known as glare, making it difficult to discern objects from the background. Coupled with blur spots from certain eye diseases can make it rather difficult to navigating particular environments.

Tools to help Enhance Contrast Sensitivity

Filter lenses (which can be in the form of tinted glasses or tinted contact lenses) can help make objects stand out more by selectively allowing only certain colors of light to pass through to the eye thus enhancing the difference between light reflecting off an object versus light reflecting off a background. This factor is dependent on the overall light available. If the background light is too dim, filters may remove too much light making it difficult to see in general. For example, many people may find it too difficult to navigate indoors with a dark pair of sunglasses. Enhancing contrast may help someone better distinguish the sidewalk from the driveway. Some patients may find that they have an assortment of filter lenses to use depending on what lighting condition they are in.
Polarized lenses may also help cut down glare by only allowing light of a certain orientation to pass through the lens. This is especially helpful if the environment has a body of water, or is full of objects, such as cars in parking lots, that allow for light to bounce in many directions. Excess glare can cause disorientation.
Many electronic devices and some computer programs have contrast enhancing software that can not only cut down the glare, but also digitally invert colors. For example, black print on white background can be changed to Yellow print against a Black Background.
There are also many behavioral modifications that can help one function better such reducing clutter (or creating a less busy background), using an appropriate light source that allows for light to be specifically directed at a surface, and separating and organizing items by contrast to allow for easier and quicker access. e.g. black and white socks.
Manipulating contrast is one of the few tools to help low vision and other patients to improve the quality of their live.