For over 30 years I have been answering this question, and I have heard fellow optical professionals provide some less than professional advice around this lens choice. So, let’s start with your sunglass basics. To choose to mirror or not mirror you must first understand what you are trying to accomplish with this tool that is your sunglasses. If they are just generally for cool factor then choose whatever you like, but in most cases, we are choosing to wear sunglasses because they are fixing something we want fixed. In the case of most common sunglasses, it is to reduce the amount of “bright” or visible light in sunny conditions. As discussed in a different blog, sunny conditions impact everyone, and some of us may be more sensitive than others. If you are in fact, light sensitive, meaning you are very uncomfortable on a clear, bright day without putting on a dark lens then a mirror may be a good choice for you.
Mirror coatings, while they can have a “cool factor” impact on the look, play the important role of making your lenses even darker. The mirror as you might expect reflects light away from the surface of the lens and allows less light through to enter your eye. So for those of you who are “light sensitive” or have migraines frequently triggered by light, then a mirror coating will allow you to operate your vision from a darkened space that helps your eye better regulate the amount of light needed and create sharper focus. By the same token, if you are not very “light sensitive” and you are like me and find yourself turning on lights even in daylight hours to “see better” then you may not be a good candidate for mirror coated lenses as they may frequently feel too dark and you may find yourself taking off your
sunglass to help your eyes focus.
So to recap, a high-quality mirror coating is designed to further reduce the amount of light that can enter the eye. This is good if extra help is needed for your eye to regulate the light getting to the receptor cells at the interior of the eye so you can better focus. However, if you prefer a little extra light in many cases a darkened lens is plenty adequate to ensure good vision and protect the light receptor cells from light overload. Be aware that if you choose a mirror surface, you must add an anti-reflective coating to the inside of the lens to allow light to escape clean and provide you with best clarity overall. If I am your optician, you know that I never make this coating optional, it is required to provide best performance from any sunglass, mirrored or not. We will talk more about that subject, in another post.
Peace, Love, & Great Glasses,
Paige Buscema, ABOC, VALDO