Tinting of Acrysof Toric IOL's and Astronomy

[MrAstro]

I'm about to have some implants put in and I'm a keen amateur astronomer who enjoys observing faint galaxies at the bounds of dark adapted vision using averted vision. My vision pre-operation is +6.5 with some astigmatism and +8 with reading glasses (hyperopic)

I note that Acrysof Toric IOL's seem to be tinted. The best info I could find suggest that it cuts about 30% of blue light.

This worries me because I don't want to reduce the light that reaches my dark adapted eyes at all - in fact the whole point of increased aperture on astronomical telescopes is to maximise light and ensure every photon reaches your eye.

Can you allay my fears about the tinting at all - or should I worry about it and intervene in terms of the choice of lens that my refractive surgeon would otherwise implant.

I also note the lens is 6mm - I always thought a dark adapted pupil could be up to 7mm in size.

I'm currently 43 years old.

[JodieJ]

To the best of my knowledge, there is no credible evidence that blocking violet light offers protection against age-related macular degeneration.  I believe that AMO, Alcon, and Zeiss all make high quality IOLs.

[Zobert]

It would seem that there is very little data to support the phototoxicity of blue light hypothesis, or the possible adverse effects of blue-filtering.  I have not seen anything that supports that Alcon's blue-blocking IOL reduces AMD risk, or reduces circadian hormone production.  For me it comes down to what makes sense.  I think it is clearly demonstrated that the receptors in the eye that regulate circadian hormones respond to blue light, and that Alcon's blue filter filters 50% or more at those wavelengths.  Zeiss now uses a violet filter (shorter wavelength) that reportedly lets in more blue light but filters the higher energy violet.  It seems like a decent compromise in light of the paucity of good data.  Unfortunately, I think my choice is blue-filtering or UV-only filtering.

[JodieJ]

There are a number of papers available online that explain and/or demonstrate why Alcon's blue-light filtration feature does not adversely affect circadian hormone production.  All of these papers were written by paid consultants of Alcon.  I could find no research demonstrating that the blue-light filtration feature actually results in depression, insomnia, etc.  (Mainster's paper does not demonstrate that the blue light filtration in Alcon's IOLs has any adverse effects on recipients.)

[Zobert]

The non-toric monofocal Alcom lens does come in a UV-only blocking filter.  I am considering a monofocal IOL for cataracts and concluded that blue-blocking is a bad idea because it affects circadian hormone production (see some of Mainster's papers - he was not funded by AMO for his earlier work).

I wonder why optometrists do not recommend the same blue filter for eye glasses and contacts if indeed there is any real evidence to suggest that blue light can damage the retina.  Alcon makes contacts that they do not have a blue filter; one might ask why not.

[JodieJ]

Archillea, when a researcher has a vested interest in obtaining particular results, this constitutes a serious threat to the validity of his/her research.  It makes me wonder how many other studies were conducted but were never published because the findings were clearly not what was hoped for.  Shortly after Alcon introduced its blue-light blocking feature, another corporate player introduced IOLs that blocked violet light, claiming that this was what was REALLY needed (in their opinion, anyway) to prevent age-related macular degeneration.  If there is independent research about this issue, I've never found it.

The toric IOLs described by Ringo999 (above) sound really interesting.  But I suspect that the skill/experience of the surgeon might be at least as important as the actual IOL used.  MrAstro, in your place I'd probably schedule an appointment with my surgeon to discuss my concerns and the possibility of using a clear IOL lens and other astigmatism-correcting procedure(s).  If I felt reassured after this discussion, I'd go for it.

[Craig10x]

And again...i have the Acrysof torics with the uv ray filtering...to be honest, i don't notice any difference in the way i see colors then i did prior to getting my cataracts and wearing glasses...in fact, the filtering seems quite beneficial in that i find i never seem to need to wear sunglasses in any situation outdoors...

To use an old expression...i think you might be making a "mountain out of a mole hill"...i am sure you will be so happy with the way you will see after the surgery that you won't even notice any difference either...

[Ringo999]

Hi Mr Astro,

A few points for your consideration;
* The yellow tint (violet or blue blocking) is designed to filter out potentially harmful rays, but it does alter colour perception, as is evidenced by many patients who have an untinted lens implanted in one eye and a yellow lens in the other. They often can notice the difference. Whether this would affect your work, I don't know?
*You mention you are hyperopic with some astigmatism. To my understanding, the Alcon lenses are available in 0.50Dincrements for common dioptric powers for the spherical component of the lens and for the cylindrical component that corrects for the astigmatism they come in 0.75Dsteps. This means that you will get a lens that is the closest fit. There are more recent advances in manufacturing that have allowed some European manufacturers to offer custom made toric IOLs that are manufactured to your exact requirement in 0.01D increments for both the spherical and cylindrical component. This may in fact have a greater impact on your ability to see well post surgery? These lenses are not available in the US? Not sure where you are based? Oculentis in Germany offer the lenses manufactured to 0.01D and Lenstec offer them to 0.25D. I am not sure if you can get the later in the US. Oculentis offer a yellow lens, not sure about Lenstec.

Good luck with whatever you choose and it will be nice for you to hopefully not need your +8 glasses all day long anymore!

[MrAstro]

I noticed that too Jodie and I'm very sceptical that a filter would increase scotopic vision.

How many eyepiece manufacturers for astronomical telescopes sell them with integral filters. (rhetorical question)....

Any filter is going to decrease the available light reaching the eye - even if it is in a narrow spectral range.

Notice that they say it increased under different assumptions - I'd like to know what those assumptions were - maybe it was a light source which didn't include the filtered wavelengths :-)

The ridiculous thing is age related macular degeneration would occur in people with a yellowed natural lens anyway - so much for blue filtering (via natural biological processes) preventing age related macular degeneration.

I sort of want to take some action regarding my lack of choice - but like I think I mentioned earlier I feel a bit powerless in the matter. My pre screening examinations cost $600 - it's hard to back out and find someone else - and then the other manufacturers lenses aren't without problems either (notwithstanding that they might be clear).

The frustrating thing is I bet it would be easier for them to manufacture a clear lens than a yellow one.

[achillea]

Here is a more recent evaluation of tinted vs untinted lenses, published under the same aegis you find suspect:

http://www.touchophthalmology.com/articles/blue-light-filtering-intraocular-lenses?page=0,5

It is of course possible that the information contained in these papers may be tainted by commercial interests, but for those with some background in physics, such as MrAstro, the plausibility of the arguments be significant.

[JodieJ]

I downloaded and read the paper you referenced.  The author is a paid consultant for Alcon (the manufacturer of Acrysof IOLs), as stated clearly in the paper.  (How could I have known this before even downloading the paper?)  I've been told that the fees paid to a consultant involve six figures in terms of US dollars.  This makes me more than a little sceptical about any "genuine concern about damage caused by exposure to certain wave lengths" on the part of the author.

I was not able to find any credible evidence that Alcon's blue-light blocking feature helps to prevent age-related macular degeneration.  As I recall, the basis for this claim was some weak correlational findings that did not hold up to re-evaluation.  On the other hand, I could find no credible evidence that this feature was in any way harmful.

[Craig10x]

Oh just to clarify, i didn't mean tint i meant the ultraviolet light filtering..whatever that is...LOL

[Craig10x]

I have Acrysof Toric IOLs with the blue tint...no color problems at all..in fact, my color perception is better then it has ever been, certainly better then when i was nearsighted and wore glasses (prior to developing cataracts)...

[achillea]

Jodie, about 2 1/2 years ago when I got my reStors, I ran into references to an earlier, untinted version--which was of course what I would also have preferred, but which was not available for my surgery.  As it happens, my color vision is superb (she said in all modesty), though I obviously have not tested my dark adaptation for astronomical tasks.  

It seems that the addition of the yellow tint was based on genuine concern about damage caused by exposure to certain wave lengths, as discussed (and referenced) in this paper:

http://www.touchophthalmology.com/articles/achieving-best-visual-outcomes-monofocal-intraocular-lens?page=0,3

MrAstro, you will also find technical mention here of dark-adapted scotopic spectral sensitivities.  You may find it reassuring.

As an aside, my husband has also noted the 'demon glint' from my implants.  He says it's a tad eerie, all right.

[JodieJ]

Good luck with your surgery.  I really don't think that you'll lose the edge, and you'll be able to use your old glasses as a paperweight.

[MrAstro]

Just an edit on the lens type - I made a typo

It's an Acrysof IQ Toric Lens. I'm a fumble fingers these days on the keyboard...

[MrAstro]

I wondered what they meant by eye glint - it's kind of cool that now that I'll be eligible to star in the next exorcist film :-)

I rang surgeon after I wrote my first post to identify the exact lens they are going to use rather than just guessing. It's a Acrysof IT Toric Lens. I'm happy with all the features of the lens itself with one noteable exception of course :-)

I'm also happy they seem to think it has good rotational stability - as long as they get the positioning right in the first place.

It's a good hint re: the Lasik touch up - I must remember that just in case and hope they won't have to of course.

I found this brochure that shows their range of lenses and some of them were clear - just not this particular type. I think I'm going to have to suck it up and take it - I don't think I like the alternatives very much - it's just such a shame about the tint.

Deep sky astronomy is all about hunting faint galaxies on the edge of perception. It's quite competitive in terms of whether you can see what your fellow observers are looking at. It's a crying shame I'm going to lose the edge that I could have otherwise had and inherit the yellowed eyes of an elderly person at such a young and spritely age ie. 43 lol :-)

[JodieJ]

Don't laugh--but when I first read the research that constituted the "scientific" basis for Alcon's blue light blocking, I wondered whether the idea originated in their marketing department.  What a sales pitch--an IOL that prevented age-related macular degeneration!  And no one could prove that the yellow tint didn't work--at least not for many years.  

Strangely, I believe that an older version of Alcon's ReStor was available in 2 versions:  both with and without blue light filtration.  I seem to recall reading that the version without the tint was marketed to people in certain professions who needed exceptional color discrimination ability!  (If you do some extensive online research, you can probably find the reference.  Or you could try calling Alcon's customer service.)

My Acrysof lenses are aspheric (without astigmatism correction), and there's only one feature that I don't like.  In certain lighting conditions, my IOLs have a visible glow to onlookers.  (It's similar to the glow in the eyes of the alien children in the old horror film "Village of the Damned".)  I believe that all the yellow tinted Acrysof lenses share this feature.  Lenses from other manufacturers (such as the one-piece Tecnis monofocal) don't emit a glow.

I don't know what your goals are for your post-surgery vision.  For a refractive lens exchange, you could probably find a surgeon willing to provide a no cost LASIK touch-up to eliminate astigmatism and any residual refractive error.  This option would eliminate the need for a toric IOL, and it would probably provide your best uncorrected vision.  Alternatively, limbal relaxing incisions at the time of surgery might also work well, depending on the skill of the surgeon.    

[MrAstro]

Thanks Jodie,

I know it probably isn't an issue for most people but it annoys me that Alcon effectively cripple their prosthetics. It's really sad and depressing you can't get them without the tint ie at least get a choice in the matter.

From what I've read I would agree with your analysis that in other respects they are the best on the market. I just wish you could order them with this accursed tint - it seems to be a solution in search of a problem - given the lack of hard evidence on the benefits.

[MrAstro]

And another reference to the issues I'm referring to. I hope the surgeons don't have a learning curve with other products or are resistant to obtaining different  lenses due to vendor relationships or suchlike.

http://www.eyeworld.org/article.php?sid=2123&strict=&morphologic=&query=

[MrAstro]

I thought it might help to show some citations rather than just merely saying 'I found some references on the subject'

http://www.nick-lane.net/blue%20blockers.pdf

http://www.eyeworld.org/article.php?sid=2122&strict=&morphologic=&query=

http://www.amo-romania.com/Document_Files/HealthyBlueLight_87rjgj.pdf

[MrAstro]

I've done some research and it does suggest possible reduced contrast in low light - in the blue end of the spectrum - so I'm now in a quandary about whether to pull out of the surgery unless the surgeon can find me an equivalent lens that isn't blue blocking.

I've got a huge investment in visual astronomy equipment. Some of my lenses cost $1k alone and I spent a year building a 16" newtonian reflector - so I'd be gutted to find out that I lost sensitivity on the faint extended astronomical objects rendering my equipment useless.

I bet the studies with regards to patient satisfaction don't have many astronomers working in scotopic conditions - it's not simply walking around at night on a lit street.

[John C Hagan III, MD, FACS, FAAO]

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[MrAstro]

I wasn't worried about colour perception per se. I was worried about how tinting affects the eyes low light contrast sensitivity in what I believe is termed scotopic conditions. Astronmers use averted vision which mostly activates the rods (don't cite me on that - I'm no expert).

[John C Hagan III, MD, FACS, FAAO]

FIRST LET ME CORRECT a mistake. The father of the IOL is Sir Harold Ridley MD not Dr. Choyce. The latter designed a very successful anterior chamber IOL.

The tints are to protect the retina/macula from ultraviolet and infrared light which can cause macular degeneration and which the human lens does.

I have never read an article that states that blue or yellow lens alters color perception but I would encourage you to do your own research and discuss with your surgeon.

JCH MD