1. Intentionally Use Higher Contrast Colors
In the classroom, place items on high contrast backgrounds so they stand out for your low vision student. If the item is dark colored such as a black pen holder, place it on a light colored surface such as white or yellow. If it is light colored such as the tray of washable markers, place it on a dark colored surface such as a dark brown desk. For announcements or homework assignments on the board, make sure to use plain black marker rather than blue, red, or green. Choose one that is not washed out yet. Rather than making every area high contrast, intentionally choose those objects or areas that are most essential for the student to access in order to function as highly as possible. That way, the most important items will truly stand out from the rest of the environment.
2. Add in Safety Supports
Where there are areas in the school environment that the low vision student travels regularly, use high contrast to mark out danger spots to maximize safety. For example, stairs can pose a problem especially in poor lighting and when each step is the same color. If the stairs are black, blue, or dark grey, place a strip of bright yellow or white tape along the top of each so steps are more clearly delineated from the next. Another example from my own experience is electrical cords. These can be tripping hazards in the classroom and yet are necessary for running the equipment needed to use instructional and assistive technologies like projectors and video magnifiers. If the cord is white or light grey, it will be hard to spot on the white tile floor. Instead of letting these cords hang out where they will, use electrical tape to pin them down out of the way. Choose black tape to increase the contrast against the white floor.
3. They Can’t Tell Us When They’re Missing Visual Information
As teachers, we must remember that children will likely not even know when they are missing out on visual information. They only recognize what they are seeing, not what they are missing because they can’t see it. Even low vision students with good acuity may miss details due to low contrast sensitivity and we need to take this into account when presenting educational material. For example, in a storybook, a student may not notice the green frog if it is on green grass. So if the picture contributes to understanding the content of the story, rather than just being decoration, we need to ensure students are not missing important elements. We need to ask them questions to determine if they are able to see all the important elements instead of assuming that they can. Instead of asking, can you see this? Try, “tell me what you see here” instead. If you just ask the former, they will say yes of course, because they do see something. But without more specific questioning, we can’t know if what they are seeing is the same as what we see or much less. If you ask the latter, their answer will provide more specific information about what they are noticing and what they are not.
4. Color Filters and Lighting
Good contrast sensitivity is essentially the ability to distinguish an object from its surrounding background, so if you can’t, issues will result. In many ways, a measurement of contrast sensitivity provides a more accurate indicator of real-world functioning than acuity does. Many causes of visual impairment result in reduced contrast sensitivity in addition to CVI such as cataracts, diabetic retinopathy, or traumatic brain injury. Color filter overlays can help enhance contrast depending on the environment. Yellow or amber tones are often used; blue light blocking filters can be helpful outdoors. Bolding in writing and increasing the lighting or changing its position when trying to see something can aid patients in perceiving objects against their background.
5. Writing Considerations
One of the most vital things a student with low contrast sensitivity needs to be able to see is his or her own writing. Special writing paper with bolded lines and more space between each can be purchased to help the student write in a straight line. The standard three-hole notebook paper has very faint blue lines that can be invisible even when using a video magnifier. Make sure the student is allowed to and/or provided with something darker to write with than a number 2 pencil such as a 20/20 pen or with a black marker. This will cause their writing to stand out against the white paper. Choosing colors that contrast sharply with each other is important outside of the classroom as well. At lunch time, if the table is white, providing black, red, or blue plastic silverware and napkins will help the student keep track of their utensils much better than with white ones. At gym class, consider taping the line-up spot with bright yellow, orange, or white tape to help the area stand out against the brown floor.
Basic Principles for Enhancing Color Contrast
- White against black gives the highest level of contrast
- Don’t use dark colors together such as black and dark gray or dark green and red
- Don’t use light colors together such as white and light gray or yellow highlights on white paper
- Don’t use pastel colors with each other
- Use bright, saturated colors for independent living tasks
- Highlight danger spots using masking tape (bright yellow duck tape on the edge of black stairs or a strip of bright orange on the pull area of a cabinet door or drawer)
- Don’t write on the board with yellow, pink, light green, or almost dry markers.
- Consider using a black dry erase board, instead of white, with bright neon liquid markers.
- Low vision students need sharp, consistent, light on dark or vice versa markings to notice them.