Question: I suffer from mildly-moderately photophobic. Glare from headlights and sunlight glare from reflections are mine primary buggers. What do you think about the Zeiss Drivesafe lenses? According to Zeiss DriveSafe white paper) they work the best when blocking wavelength from 440–470 nm range. I am considering them for my next lenses, as they look “normal” (I can’t wear any of those “alien type of lenses”, as I work in a company where I would probably look weird to my clients :). I just need some confirmation whether they are good choice or not. I currently have ordinary Zeiss lenses, without anything specific inside.
Answer: Thanks for sending the DriveSafe white paper! It is full of interesting information and what I liked best, a DuraVision DriveSafe spectrogram from Zeiss:
The focus of this answer will be on the glare reducing ability of the DuraVision DriveSafe lens as it can be deduced from the lens’ spectral transmission properties, namely its blue light filtering/blocking capacity.
Disclaimer: My interest in blue light and blue light filters is due to my problems with light sensitivity (photophobia), discomfort glare, and computer eye strain. I am not a vision scientist.
First, note that blue light might not be the only cause of discomfort glare and photophobia, although it has been found that discomfort glare and photophobia are principally caused by blue light (more so than by longer wavelengths of light of the same intensity) [Action spectrum for photophobia (2003)].
It is therefore not surprising that our internal blue light filter, macular pigment, blocks light in the blue range:
Zeiss DuraVision DriveSafe transmittance compared to other blue light filters
DuraVision DriveSafe doesn’t vary a lot (if at all) from DuraVision BlueProtect (see below). If you carefully compare the two spectrograms you’ll note that (at any given wavelength) the percentage of light transmitted through the lens is about the same.
Given these transmission properties Zeiss DuraVision DriveSafe and BlueProtect lenses belong to the group of filters that block blue light slightly more than regular clear lens. This has advantages and disadvantages.
The main advantage is that you can safely wear it when driving at night. DriveSafe lens is designed for everyday use according to Zeiss. As such it should fulfill the ISO requirements for category 0 ophthalmic lenses, meaning that the total transmittance of visible light is over 80%. This is important, because stronger blue light filters might reduce your night (scotopic vision) too much and are therefore discouraged or forbidden in some countries (you should check for your country).
On the flip side, Zeiss DuraVision DriveSafe lens (and any other category 0 ophthalmic filter) might block too little blue light to reduce discomfort glare in people with greater light sensitivity.
In conclusion, if your discomfort glare is indeed principally induced by your greater sensitivity to blue light, Zeiss DuraVision DriveSafe lens can certainly help you feel a bit less discomfort glare when driving at night.
For the people who are not very sensitive to blue light and glare (a great, great majority) that’s perfect.
Will Zeiss DuraVision DriveSafe lens work for you?
What is impossible to know in advance is whether Zeiss DuraVision DriveSafe lens blocks enough blue light for your eyes to feel comfortable when driving at night. The only way to know for sure is by trying.
The trouble is that glasses with the Zeiss DriveSafe lenses are probably quite expensive (you might spend at least $200 on glasses with Zeiss DuraVision DriveSafe lenses). Then you might find out that they work great for you, or not: what if the oncoming traffic headlights continue to bother you considerably despite Zeiss DuraVision DriveSafe lens?
Normally, you won’t be able to return them because, being prescription lenses, they are custom-made just for you.
A less costly blue light filter test
A cheaper alternative might be to spend $20US on GLARminŸ Tester. You can wear it over your current lenses/prescription glasses. (The tester kit is not a stylish option, but unless you are a bus driver no one can see you when you drive at night).
In addition to its low price, the advantage of the Tester is that it comes with 8 filters that filter very different proportions of blue light:
If Filter 7 works for you, you can be pretty sure the Zeiss DuraVision DriveSafe lens will help you (although DriveSafe is still a bit weaker than Filter 7, but not significantly).
If Filter 7 doesn’t help you, you can try a stronger Filter 6, then 5, 4, and so on, until you find the one that cuts enough glare to make your eyes feel comfortable when driving at night.
Prior to trying the Tester’s filters when driving at night, you should check whether stronger blue blockers are allowed for driving at night in your country.
So there is not so much difference between BlueProtect and DriveSafe! I have to say I am surprised! It’s marketing gimmick then!
Last time I ordered my lenses with all coatings except the BlueProtect, because I heard blue filters ruin contrast. From this perspective, I should definitely order Blue blocking coating as well, as the extra cost was negligible.
In my country, basic Zeiss BlueProtect lenses cost about $120-140US. On the other hand, DriveSafe lenses cost around over $300! With discount ($360 is the regular price)! $420 if you want transitions (don’t know is it beneficial for the glare issues, as it block’s the sunlight).
Also, Zeiss claims DriveSafe lenses are digitally enchanted for the change of the pupil size, but I guess it’s hard to compare with BlueProtect. Anyway, my brother wears Hoya lenses with the blue filter (called Blue Control), and according to him, it’s very bad as it completely distorts color.
Transitions might block a bit more blue light see examples of spectrograms and further comments in here and here. Note that for your problems of glare when driving, you should be looking at the unactivated curve because transitions tend to be activated by UV light:
– at night there is no UV light (artificial lights don’t emit it), and
– during the day UV light is largely filtered by cars’ windows and windshield.
Color distortion & blue light filters: You can’t block blue light and see it too – more in this post. Unfortunately I haven’t been able to find the spectrogram for Hoya Blue Control, so I can’t say anything about it.
However, you should know that science couldn’t figure out for a long time whether yellow tinted lenses actually help vision or not. The issue was finally settled when technology allowed them to measure macular pigment optical density (MPOD) [The visual effects of intraocular colored filters (2013)]:
-people with low MPOD appreciate having an additional, external blue light filter because it makes them feel better and it improves their visual performance. They don’t seem to mind color distortion.
-people with high MPOD don’t appreciate blue blockers at all and are really annoyed by color distortion, and
-there are many possibilities between those two extremes, such that people closer to low MPOD might appreciate stronger blue light filters and people closer to high MPOD might appreciate weaker filters.
You simply cannot know if a filter will help you and how much its color distortion will disturb you, unless you try it. Alternatively you could have your have your MPOD measured (alghough it is not that easy to find places that can do it). But even with a known MPOD score, you should be careful about making predictions, because there are always cases that don’t fit the statistics and no one knows who fits and who doesn’t.
Blue blockers & marketing: It is hard to say if Zeiss DriveSafe lens is just marketing trying to outsmart the customer – maybe they call it DriveSafe because in addition to the blue blocking coating, they also tackle two other issues (one is pupil size, that you mention, and the other is that they try to take into account the different distances and positions at which one views things like the dashboard, rear-view mirror, etc… see the above mentioned white paper).
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