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. This why vision is so poor at night. We require light to see for many reasons. Light helps to create contrast with the objects we are viewing in relation to their background. Light aids in our ability to have high definition and resolution.
Some patients are bothered by glare, as some medical conditions result in increased 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 it is critical to match the sensitivity of the patients sight with their lighting needs and the tasks that they desire to participate in.There are lighting systems that are corrected for wavelength, spectrum, brightness, and color temperature, to name a few, that enable patients to get the most natural lighting conditions. In addition, filters may be added in the form of glasses that will help eliminate glare with only minimal reduction in intensity, thus maximizing contrast and viewing ability.
Paint and wall coverings are one of the most effective treatments to alter the ambient lighting of a room. The use of dark colors will reduce the overall ambient lighting while lighter colors will brighten the room. Ceilings painted with an off white paint will increase the brightness of the room and will increase the perceived size of the room, especially when table and floor lamps shine light towards the ceiling. Light colored paints should be used 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 patients with low vision to navigate more easily and accent the features of the room. 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. This is the amount of 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 is not designed to provide lighting for reading, cooking, or performing specific tasks.
Once this is done the next step is to select the proper task lighting to meet the specific goals of the patient 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 provide high levels of light in a cost-effective manner. Do not use 300-watt halogen or incandescent floor lamps because they use too much energy, generate too much heat, cause excessive glare, and can 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 significantly because most of the light shines on the ceilings and walls or is absorbed by the lampshade, or it simply causes excessive glare.
The use of desk and floor lamps that direct light specifically on the work areas are the best solutions to help patients to read, write, play cards, see their food, and perform their hobbies. Desk lamps generally consist of a silvered or white reflective surface that directs all of the light on the reading material.Because light is directed in a precise manner, all of the light illuminates the reading material and stray light does not cause glare. Desk and floor lamps are available in various styles and they use a variety of light bulbs.
We do not recommend the use of Halogen light bulbs as they generate a lot of heat. When using incandescent light bulbs, use a low wattage bulb with a gooseneck that allows you to 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 are designed to produce the most efficient lighting at the optimum levels of color temperature and wave length.These lamps are NOT available in retail stores and are available from most IALVS doctors.