Lighting and Visual Impairment
The visual system converts light entering the eye into electrical signals that travel along the optic nerve to the brain. In the brain, those electrical signals are processed and result in the images we call sight. Therefore, light is most critical in our ability to see. Without sufficient light, there is no contrast between the object and the background, so vision is poor at night. We require light to see for many reasons. Light helps to contrast the objects we view in relation to their background. Light aids in our ability to have high definition and resolution.
Some patients are bothered by glare as certain medical conditions increase light sensitivity. This is a double-edged sword, as we require a good bit of light to produce contrast, but too much light causes glare. To this end, matching the sensitivity of the patient’s sight with their lighting needs and the tasks they desire to participate in is critical. There are lighting systems corrected for wavelength, spectrum, brightness, and color temperature, enabling patients to get the most natural lighting conditions. Additionally, you can add filters in the form of glasses to help eliminate glare with minimal intensity reduction, maximizing contrast and viewing ability.
Paint and wall coverings are among the most effective treatments to alter a room’s ambient lighting. Using dark colors will reduce the ambient lighting, while lighter colors will brighten the room. Ceilings painted with off-white will increase the room’s brightness and perceived size, especially when table and floor lamps shine light towards the ceiling. Use light-colored paints on walls and ceilings for patients who require higher illumination. Base moldings, door jams, and crown moldings made of dark woods such as mahogany will provide contrasting visual clues to help low-vision patients navigate more easily and accent the room’s features. Conversely, patients who are bothered by light will benefit from using darker paints, floors, and window coverings to reduce the room illumination.
Lamps and lights can significantly improve the visual function of patients with low vision. The first step is to obtain the appropriate ambient illumination – light that fills the room and illuminates the ceilings, walls, floors, and furniture, as discussed in the preceding paragraph. It is important to note that ambient lighting does not provide lighting for reading, cooking, or performing specific tasks.
Once this is complete, the next step is to select the proper task lighting to meet the patient’s specific goals when working in conjunction with the ambient illumination in the room. Patients who are bothered by glare may benefit by using high levels of task lighting in combination with therapeutic filters to block out those wavelengths that cause them to have glare. Fluorescent 15-25 watt bulbs corrected for color temperature will cost-effectively provide high light levels. Do not use 300-watt halogen or incandescent floor lamps because they use too much energy, generate too much heat, cause excessive glare, and cause fires if they tip over.
Many patients with low vision attempt to increase the lighting in their homes or work areas by replacing their table lamps with more powerful light bulbs. In most cases, this does not help because most of the light shines on the ceilings and walls, the lampshade absorbs it, or it simply causes excessive glare.
Using desk and floor lamps that direct light specifically on the work areas is the best solution to help patients read, write, play cards, see their food, and perform their hobbies. Desk lamps generally have a silvered or white reflective surface directing all the reading material’s light. Since light is directed precisely, it illuminates all the reading material, and there is no glare caused by stray light. Desk and floor lamps come in various styles and utilize a variety of light bulbs.
We do not recommend using halogen light bulbs as they generate much heat. When using incandescent light bulbs, use a low-wattage bulb with a gooseneck that lets you bring the lamp close to the material. Fluorescent bulbs are cooler, but some cast a bluish color on the paper. Many low vision doctors recommend the OTT full spectrum LOW VISION fluorescent lamps as they produce the most efficient lighting at the optimum color temperature and wavelength levels. These lamps are NOT available in retail stores and are available from most IALVS doctors.
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