To effectively improve a person’s vision, problems with glare need to be addressed when glasses or other low vision aids are prescribed.
Glare is distracting, annoying and potentially dangerous. Unlike UV, exposure to glare does not physically damage your eyes, but it can severely impair your vision. Blinding glare has caused many road and boating accidents, sometimes with catastrophic results. Some people are more sensitive to glare than others. Low vision, macular degeneration or photophobic patients can be hypersensitive to glare.
What you can do to eliminate the effect of glare on your vision
The most effective way to reduce or eliminate the adverse affect of glare is to protect the eyes with polarized sunglasses. Polarized sunglass lenses are available in a wide range of tints and transmissions, but to deal with glare effectively, it is important to use lenses that have 100% polarization efficiency. Just because a sunglass lens claims to offer 100% protection from UV A&B, do not assume the lens is polarized. UV protection has nothing to do with polarization. In fact, most fashion sunglasses are not polarized. Some sunglass lenses that claim to be polarized may only have an efficiency rating of 50%, meaning that the lens will not eliminate 100% of glare. Some sunglass lenses attempt to deal with glare with mirror coatings. The mirror coating will reflect a percentage of the glare but this method is inferior to the performance of a polarized lens.
Eye care professionals can test the polarization efficiency of any lens. Most lenses that deliver 100% efficiency will indicate such, but it is wise to confirm the efficiency rating prior to purchasing the eyewear.
What is glare?
Glare is light reflected off shiny surfaces so it can reduce vision in the presence of bright light, such as direct or reflected sunlight or artificial light. Glare can cause visual discomfort and/or disability. Discomfort glare is when overall illumination is too bright, for example a sandy beach reflecting the midday sun. Disability glare is reduced visibility of the target due to the presence of a light source somewhere in the visual field, for example a road sign illuminated by headlights.
Glare hinders visibility by reducing the total amount of visible light seen. When the eye is exposed to glare, the pupils constrict and limit the amount of natural light transmitted to the retina, and therefore, limit the image that the eye perceives. Glare can also reduce the contrast of the rest of the visual scene by the scattering of the bright light within the eye. Glare is caused by stray or scattered light raising the luminance of both the visual target and the background to the same visual levels, thereby reducing the contrast and causing a blinding effect. This scattered light forms a veil of luminance, which reduces the contrast, and thus the visibility of the target.
Cataract surgery reduces disability glare from interocular light scatter. Also contrast polarity of text (black on white versus white on black) can make a substantial difference for readers with reduced contrast sensitivity.
Product tip! Did you know that all sunglasses are not created equal? Filters attenuate blue light, a crucial component for those with contrast sensitivity. To effectively improve a person’s vision, problems with glare need to be addressed when glasses or other low vision ads are prescribed.