You have had your eyes examined, chosen a frame for new glasses and your optometrist may have recommended adding a coating to your new lenses to improve both the quality of the lenses and the quality of your vision. Are lens coatings really necessary or is this just an added bonus which usually comes with added expense? Lens coatings can improve the performance, longevity, durability and appearance of your glasses, while also providing protection for both your lenses and your eyes. The added expense is usually worthwhile, but different coatings offer different benefits, and a number of factors need to be considered before making a decision. These include your lifestyle, vision needs and budget.
ANTI-REFLECTIVE COATING
As light contacts any clear surface, such as the lenses of glasses, most of it passes through but a certain percentage of it is reflected back. An anti-reflective coating is typically applied on both the back and front of the lenses, reducing the amount of light reflected off the surface and allowing more light to pass through the lens, enhancing vision. Glare is eliminated. Reflections from the lenses of glasses make it difficult to see the wearer's eyes, but with anti-reflective coating the cosmetic appearance of glasses is improved. Anti-reflective coating is particularly beneficial for people who drive at night and find reflections of street lights and headlights of oncoming cars disturbing. Eye strain from reflections during visual tasks such as computer use is minimised.
SCRATCH-RESISTANT COATING
As well as being irritating, scratched lenses can impact the clarity of vision and cause headaches and eye strain. Plastic lenses are more susceptible to scratching than glass lenses, and many plastic lenses today contain a built-in scratch-resistant or "hard coat" on the back and front of the lens surface. While no lenses are completely scratch-proof, a scratch-resistant coating will make them less vulnerable to scratching and prolong their life. To further protect the lenses, store them in a case when you are not wearing them and clean them with a microfibre cloth.
It is important to note that scratches cannot be removed or buffed out of lenses once they occur. It is the curvature of the front and back of the lenses that determine what prescription they are and thus how well you see the world. Any attempts to buff or resurface out the scratches on lenses will change this curvature as well as the prescription and lead to distortions in the lens and blurred vision.
UV-PROTECTIVE COATING
Over time, exposure to the sun's ultraviolet (UV) rays can lead to vision problems such as cataracts and retinal damage. UV protection on glasses protects the eyes and the delicate tissues around them from these harmful rays. Some lenses have a certain amount of UV protection built in, but a UV-protective coating is advisable, particularly for people who spend a lot of time outdoors. Lenses should offer 100% protection from UVA and UVB rays.
TINTS AND BLUE-BLOCKING COATING
Tints may be applied to lenses to cut down on the visible light entering the eyes, helping to reduce discomfort in bright light particularly in people with light sensitivity and degenerative retinal conditions. Certain tints may increase contrast, improving vision. Although not definitive, some research has suggested that reducing exposure to blue light from digital devices minimises its harmful effect on the eyes and the body. A coating which blocks blue light may be beneficial.
ANTI-FOG COATING
Fogging of lenses often occurs when moving between cold and warm environments, playing sport and, as we are discovering during the COVID-19 pandemic, wearing masks. It usually takes a few seconds for vision clarity to return. Not only can this be awkward in certain situations, but it can also be dangerous. An anti-fog coating can prevent this from occurring by eliminating the condensation of moisture that leads to lens fogging.
Do you need your glasses indoors, outdoors or both? Do you frequently drive at night? Does your work involve long hours at the computer or in the sun? Are you required to do a substantial amount of reading? Do you need to wear glasses for your sporting activities? What does your medical aid cover? Is there a co-payment on glasses? Lens coatings can vary in price and most expensive does not always equate with most effective. These factors along with the guidance of your optometrist will help inform your decision.