We have already gone over a huge amount of information regarding prescriptions, frames and lenses, but we haven't yet touched on the different lens options that are available to you!
There are a number of options for addons and customizations for your new lenses, so why don't we explore some of them?
Spherical vs. Aspheric lenses
Spherical and aspheric lenses can come in many technologies, Single vision or Progressive, but there can be a significant difference to the
two. Spherical lens technology is the older of the 2, and these lenses tend to be more obviously concave or convex, depending on the prescriptions. Spherical lenses have more curvature to the surface of the lens in general. This means that when you are using a spherical lens you will notice a more "coke bottled" lens look, the higher the prescription is, the worse this effect will get. Who remembers Bubbles from The Trailer Park Boys? He was most certainly wearing spherical lenses! Also, if the lens is very curved, we may need to bend and mold whatever frame is chosen to fit a higher curvature. This can be a problem, because over time, (especially with plastic frames), the frame will inch its way back in to its regular original curve, leaving the lenses ready to jump out of the frame, an effect opticians call "Lens Rolling". Aspheric lenses are much flatter and fit better in most ophthalmic frames, requiring less frame manipulation over all, and leaving you with a nicer pair of lenses to wear - not just for you visually, but also for others when looking at you while you wear the glasses. Aspheric lenses also tend to be on the thinner side by default as well, even when comparing the different lens index's (which we covered in a previous article). Whenever possible I always use an aspheric option for my patients, as they tend to be nicer lenses overall to wear. However, being that spherical lenses are the older technology of the 2, they do tend to be more affordable, so for someone with a minimal prescription and a tight budget can certainly get by using the spherical lenses.
Usual Coatings
- Hard coat: This is a standard to use on lenses, as it helps to keep a lens scratch resistant. Each lens company will have their own proprietary coatings, and not all coatings are the same efficacy or durability. I will mention that as of yet, there is NO Scratch PROOF lens available. All plastic lenses will scratch if they are abused enough, no matter how good a hard coat you have. However, a good hard coat can make a big difference for the usual wear and tear of a lens in glasses.
- Anti-Glare: An anti glare coating will help to reduce glare from the front surface of the lens, allowing more light to enter your eye instead of being reflected off the front of the lens. Anti glare does not cut down on back side reflections, if your light source is behind you. So, you may find that you still have some reflection or glare from the backside depending on where your light source is located.
- Anti-Reflective: Anti- Reflective coatings are superior to a regular anti-glare lens, and I would always recommend them over a anti-glare coating alone. Anti-reflective coatings will include this on the back side of the lens as well as the front surface. This gives the wearer crisp, clear vision no matter where your light source may be located.
Blue Protection coating or built in filters
Blue Light protection has become a slightly contentious topic, as depending on who you talk to you may get a different answer. Blue light protection research hit the market running when it was first introduced in lens technology, causing a leap and jump into mass use and an assumption of need based off of preliminary research that had not been peer reviewed or actually proven definitely that blue light was causing damage to the retina or macula in patients using device that emit extensive blue light. We have since realized that this is unlikely to be a cause of macular degeneration, which has cause some distrust of the blue coatings in some optical circles. It has been shown, however, that this excess blue light emitted from electronic devices can and do exacerbate eye strain, and can upset your circadian rhythm (your wake/sleep cycle). When it comes to eye strain, to understand what is happening you need to first understand why it happens. As most of us know, we are bombarded with Blue light from the sun on regular basis, and this is not new.
On the spectrum of light, the longer the wavelength of light is, the less damaging power it has. There are 2 forms of Blue light - Long wave Blue light, and Short wave blue light. Short wave blue light has the shortest wavelength than other lights on the spectrum, and it does not
reach fully to the back of the macula like the other lights on the spectrum do. Because the Short wave blue light is this way, many devices like iPads, Cell phones, laptops, etc, have dialed up this short wave of light to compete with the other wavelengths of light, which gives unsurmountable clarity of vision on the screen you are using. This causes that short wave to now reach the back of your macula, and we now believe this is a big cause in digital eye strain over all, as naturally this wavelength should not be hitting the macula so effectively. So this is a definite concern for many people (you can read more about digital eyestrain on the blog in a 3 part series explaining eyestrain). The other concern with blue light is the circadian rhythm as mentioned above. When the sun rises, it is the blue light it emits that starts our waking cycle. Naturally, this also means that when the sun goes down, and we loose that blue light trigger, our brain realizes this is a sign that it is time to wind down for sleeping. If you are working on a blue light emitting device after the sun goes down, you could be effectively tricking your brain into thinking it is still day time. So, if you find you are not sleeping as well as you once did, waking more, sleeping less soundly, and constantly feeling tired even after a full nights rest, you may want to look into limiting your blue light use after sundown. At the very least, you should stop using any device that emits blue light a minimum 2 hours before you go to sleep at night. Yes, that means no more doom scrolling on Facebook in bed, and I mean it! More and more research on blue light and its effects on your vision and health are ongoing all the time, so stay tuned in the future, we will always post interesting updates and advances in lenses and blue light here for you to familiarize yourself with.
Photochromic filter
You either love them or you hate them, seems to be the general consensus on Photochromic. The most popular Branded version of this is called 
Transitions lenses, who boast clear lenses that turn into shaded sun lenses when exposed to UV Rays, but many lens companies may have their own proprietary form of the lens shading technology. The people who love them (including me) love the convenience of not needing to carry around your prescription sunglasses, as soon as you go outside and the lenses are exposed to UV, they will start to darken. The have a darkness variability to them, so on super bright days they will turn to the fullest darkness possible, and on cloudier days you will notice they may not go as dark, but they will still change, as clouds do not prevent UV light exposure. A couple quick things to mention about these kind of lenses 1)The stronger your prescription will be, the more likely your Photochromic may not go as dark as someone with the same lens but a much lesser prescription. 2)Photochromic lenses require UV filters to change into sun lenses. Since most vehicles these days have a built-in UV filter in to the windshield, you will not find the Photochromic lenses will not darken much if at all when driving in your car. The Transitions Brand of lenses have an option called, Transitions ExtraActive which boasts the ability to change in to sunglasses based off of UV Rays as well as added heat in the environment, making them more likely to change when in your vehicle if it is a hot and sunny day.
Polarization
You will pretty much only find a polarized lens in the sunglasses these days. Polarization will cut the additional glare out from your vision
and make colors and images really pop when you look at them. Every so often, you may come across an instance where polarization is not allowed, the biggest example of this would be many pilots! Many gauges, dials and devices will be visually effected by the polarizing filter making them very hard to see accurately, so in those kind of situations, you are certainly going to want to leave that polarization out of your sun lenses. Just like all other coatings and filters, the degree of quality in a polarized lens can vary, but even the worst polarization can improve your vision a fair amount compared to a sun lens that has no polarization at all! Some sunglass manufacturers have invested in improving the standard polarization in their lenses as well. For a great example, one of our favorite Sun brands is the Maui Jim sunglasses. Maui Jim has developed their own technology called PolarizedPlus2®. PolarizedPlus2® lenses increase contrast, color, and depth perception thanks to a patented blend of 3 rare earth elements. These elements enhance reds, greens, and blues. Basically, you still get dark lenses, but they reduce the bad colors while boosting the good ones. Not only that, but the PolarizedPlus2® technology polarizes in 2 different directions, not just one direction as the usual polarized standard filter would do.
Other Tints
When doing almost any lens, you will always have option to add a tint of some kind, whether you include polarization or not. Some people may find that working under bright white LED lights and other similar lighting may trigger migraine headaches. This can easily be relieved 
by using an FL41 or Irlen tint - which has a slightly pinkish hue to it. Many people find glare at night is very difficult even with glasses, due to the other changes happening in the eye as we age. In this situation, many doctors recommend a yellow tint in the lenses to increase contrast and cut down on excess glare, however I have also met a hand full of doctors who don't believe this yellow tint is ideal for night driving, so the answer you get on yellow tinted lenses for night driving may vary from doctor to doctor as there is no real set standard answer for this situation. There are also just normal but light sensitive people, who find in general things are just too bright for their eyes to be comfortable. For these people we can do any varying degree of tint, and in many different color and shade options! This can work for not only a prescription sunglass but also for an indoor lens when using the lighter percentages of tint. This would be best to be discussed with your optician, so they can recommend the best tint and percentage of tint for your purpose.
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These are just some of the most common add-ons or extras you may need to consider when purchasing your next set of glasses. There is a lot to consider and it can get very confusing quickly! Make sure you have a good optician who can help guide you through all of these important decisions! If you want to speak with our Optician on staff, you are always welcome to book an appointment with her in our clinic! Call 250-390-1447 to set up an appointment in our Optical Dispensary.
Stay tuned for the next portion of this series, coming soon!
