By: Paul M. Karpecki, OD, FAAO
Director of Education – PECAA
Let’s revisit the subject of High Energy Visible Light (HEVL) exposure since I’ve received numerous questions and correspondence regarding this subject since it was featured in a newsletter a few month’s ago. Here are a few key myths related to HEVL:
The greatest risk of cataracts and macular degeneration (AMD) related to HEVL is between 10 and 2pm as stated by the dermatological association.
Contrary to popular belief, the highest risk time of ocular uv and HEVL exposure is not when the sun is high in the sky (typically between 10 am and 2 pm) Although this is accurate for dermatological exposure (highest risk is between 10 am and 2 pm) that people must be especially careful of harmful ultraviolet (uv) light, it is surprisingly not the case for ocular exposure. The highest risk times are in the morning between 8-10 and then late afternoon between 3-6pm. For although there is less direct uv and HEVL at those times, the angles are more likely to hit directly into the eyes over years. And according to research there are other reasons:
- When the sun is closer to the horizon it not only is more directly hitting the eyes for people not wearing eye protection like uv coated lenses but also affects those wearing uv coated lenses via reflection from the back surface of the lens into the eye.
- Anti-reflective coatings may allow for more uv light reflectance from the back surface of a spectacle lens
- Patients don’t usually wear sunglasses (which further block uv and HEVL) at those times but more frequently when the sun is high in the sky
- Patients are also less likely to wear brimmed hats or other protective clothing that may shield the eyes during those early and late times of the day
So in advising our patients we still want them protecting their eyes during the time the sun is highest in the sky but also teach them that when it comes to ocular exposure, the 10am to 2pm time may not be the most critical time for ocular uv light’s most damaging effects!
Patients to consider BluTech lenses and other HEVL blocking technologies (Prevencia) to are ONLY those with a diagnosis of AMD or a family history of AMD.
Although this is an important category to recommend HEVL blocking lenses to (and might be considered the ‘low hanging fruit’ group), this is not the only or even largest category that would benefit from BluTech lenses. In fact I am currently wearing my HEVL blocking lenses as I work on this paper.
Any patient who uses a computer for more than 2-3 hours a day should consider this technology even if they have a plano prescription. Not only does it block the potentially harmful high energy (blue-violet) rays coming from a computer screen, tablet or other PDA, it helps with contrast on the screen and seems to relieve the strain of spending numerous hours on the computer. That has been my personal experience and that of many patients. I have seen students tell me that it provides them an edge as they can seem to work longer than their roommates/ classmates. People who spend a lot of time on video games should consider these lenses both for the contrast advantage plus the protection.
The cataractous crystalline lens served as a blue-blocking lens until it was removed. There are some HEVL blocking IOL’s on the market but not all are and therefore a HEVL blocking technologies in a prescription lens should be considered.
A very interesting group is that of children in general (who have no HEVL blocking capabilities at a young age) and especially those with sleep problems.
Evolutionally, we were not exposed to HEVL in the evenings and our melanin/melatonin is key to our sleep patterns. With the onset of TV’s, computers, tablet’s etc. blue/violet light exposure is occurring in the evenings and it will cause many people- especially children- to have sleeping problems. I’ve seen this lens technology help to correct sleep disorders.
Finally one of my favorite applications is for people who need polarized sunglasses – fly fisherman, golfers, skiers etc.
They often complain that the polarized lenses make it difficult to see anything digital- such as their cell phones, watches etc. By adding BluTech, you solve the problem! Now they have great sunglass lenses with uv and HEVL protection without any issues when looking at a flat screen etc.
Technologies keep on advancing and it’s up to us to stay on the leading edge of the key applications and insights for our patients.