Is the enVista hydrophobic IOL by Bausch + Lomb good for a myopic eye?

RonAKA, thanks for the reply.

My eyeglass prescription is as follows: L. (sphere) -4.00, (cylinder) -0.75; R. (sphere) -1.00, (cylinder) sph. I have used this prescription for many years and just lived with one pair of glasses for distance and near.

If I choose to correct my left eye for full distance, I guess I have to use lens from another brand. Is it okay to use the B+L enVista for the right eye and another brand lens for the left?

I am in British Columbia and the B+L enVista lens are not covered by our healthcare.

IOL diopters are not the same as eyeglass diopters. Eyeglass diopters are the amount of correction you need. IOL diopters are absolute power. The overall power of the average human eye at rest (lens + cornea) is 40 diopters. So if you are -4 myopic your eye is 44 diopters (too powerful hence the minus prescription to get you back to zero with the eye at rest). For an IOL though your power to get you back to zero might be more like 14-16 diopters (depending on the lens) since the cornea accounts for about 60% of your focusing power. Anyway, long story short, eyeglass prescriptions are not the same as IOL diopters. You can correct -4 myopia with just about any lens.

Thanks, david98963, for the clarification!

Back in the 70's before all this sophisticated eye measurement devices, computers and artificial intelligence, there was a simple formula used to calculate the IOL power needed for sphere correction. It was to simply add 18 to 1.25 times the eyeglass sphere correction. In your case to correct to full distance vision:

.

Left Eye: 18 +1.25*(-4.0) = +13.0 IOL power

Right Eye: 18 +1.25*(-0.75) = +17.0 IOL power

.

This is well within the power range of the Tecnis 1, AcrySof IQ, Clareon, and enVista IOLs, so there is no reason to mix brands of IOLs. Are any brands and models available in BC that are covered by healthcare?

.

Powers are no longer calculated by this crude method, although the power should be in the ballpark. If you ask your surgeon for the IOL Calculation data sheet and get the measurements for your eye you can calculate the power with a simple on line calculation method. I think one of the most accurate formulas is the Dr. Hill, Hill RBF 3.0 formula which you can find on line.

.

Has your surgeon given you an estimate for the predicted amount of residual astigmatism? If there is any interest in going eyeglasses free, it is best to correct astigmatism with a toric IOL if there is enough astigmatism to make it worth it. Generally 0.75 D or more of cylinder is worth correcting. This is not the eyeglass number however. Usually some of the astigmatism is in the lens which will be removed during cataract surgery so does not have to be corrected. The computer calculates the predicted residual based on the shape of the eye, and you would need to get that from your surgeon.

.

In Alberta the Tecnis 1 and AcrySof IQ are offered at no cost. The Clareon is an extra $300 per eye, and I am not sure about the enVista. Nobody offered that one to me here in Alberta. My brother is not paying anything for it in Manitoba. Of these my choice would be the Clareon, but there are some minor pros and cons to each. The Clareon may be most resistant to PCO, but it is always a risk.

Thanks for showing me the calculation.

The reason I am concerned about PCO is due to my retinal conditions. About a year ago, my retina specialist found that I had lattice degeneration and mild tears in the retina of both eyes. The tears were fixed successfully with laser, and I have been cleared for cataract surgery. However, if PCO formation requires YAG capsulotomy, the procedure may increase the risk of retinal detachment, as I understand.

This leads to my another question: in most cases of retinal detachment, it is very difficult to get your vision back 100%. So, if you have a more powerful IOL and better corrected vision, will you be better off post retinal detachment surgery?

The surgeon that did both of my eyes and also my wife's is Dr. Rudnisky who is a professor at the University of Alberta. He apparently has done some research on the risk of retinal detachment when doing YAG to mitigate PCO. He claims the risk is a bit overstated and is more likely about 1 in 200. Unfortunately it is a risk that many of us that have had cataract surgery will likely have to take. You can find a bit more information about his views and that of others on the issue if you google this.

.

PUBLISHED 10 MAY 2018 PCO: What’s Wrong With Doing a YAG?

.

That said, I am not a health professional and don't know to what degree your specific condition may increase risk. I however don't see how it could be influenced by the power of the IOL used. The powers you need are not unusual at all. Standard IOL powers range from +5 to +30 typically, and you are close to the middle of that range, especially for those who are myopic which is as I recall is about 90% of people. I think there may be some lenses for those who are really myopic that go into the minus range. Typically hyperopia requires lenses over +18 and myopia under +18.

.

It is hard to determine how much is manufacturer hype and how much is fact, but the Alcon AcrySof lenses gotten a reputation for being more resistant to PCO than other IOLs due to the material used and the edge design. The Clareon version is said to be a further improvement that reduces the risk of PCO. I have an AcrySof IQ in one eye and in my second eye I got a Clareon. However, I hope it will be many years and too late for you to give you feedback on which one is better! So far I have no indication of any issue. The AcrySof IQ has been in for two years now, and the Clareon since February 23 of this year.

.

Google this to find a paper which compares the Clareon to the AcrySof lenses. I think it is probably credible, but take note that in the Conflict of Interest statement near the end, one of the authors "is a member of the advisory board for Alcon".

.

Comparison of Visual Outcomes and Patient Satisfaction Following Cataract Surgery with Two Monofocal Intraocular Lenses: Clareon® vs AcrySof® IQ Monofocal Smita Agarwal, Erin Thornell

.

I found it interesting that they found that the Clareon "may induce more positive dysphotopsia than AcrySof® IQ lenses" while the AcrySof has higher incidence of negative dysphotopsia. I have some minor positive dysphotopsia in my AcrySof lens, and neither negative or positive in my Clareon lens. Positive dysphotopsia is a flash of light which is probably a reflection off the edge of the lens. I see it with my AcrySof lens when I am in a very dark area and there is a point source of light off to my left. It looks a bit like an arc shaped flash of light on the very right side of my right eye. In the scheme of things it is a very minor and somewhat quirky thing, but nothing to be concerned about.

.

Hope that helps some,

Thank you for sharing your knowledge and experience.

I am now thinking of targeting intermediate, and will see what my surgeon has to say. I probably will do the left eye first and wait for another three to six months before the second surgery. This should be enough time for my left eye’s vision to settle and stabilize. Then I can decide what to do with the right eye, targeting distance, intermediate or near.

The problem with intermediate is that you may be left in no man's land - not able to see well in the distance and also not well close up. I think a target of intermediate requires the acceptance of needing glasses. I still think that mini-monovision is the way to go. The close eye is targeted to -1.5 D, and the distance eye to -0.25 D. When the surgeon is calculating what power of lens to use they enter a target in diopters. Just near or intermediate is a little vague and may lead to a misunderstanding between the patient and the surgeon depending on how they define near and intermediate.

.

The other standard when doing mini-monovision is to use the dominant eye for distance and the non-dominant eye for near. It can be done the other way and that is actually what I have. It works, but I am not sure it is the best way of doing it. I also think it is best to do the distance eye first. If the surgeon does not get good distance then you can change plans and potentially go for distance in the second eye so you are assured of distance. You are wise to wait between surgeries to see what you really get in the first eye.

By intermediate, I was talking about the range of 20'' to 40'' with a focal point at 26''. This should allow me to work on my computer and do some casual reading.

Anyway, I probably will go for distance first with my left eye, and then decide if I want do mini-monovision. Does mini-monovision sometimes cause eye strain in just one eye? As I have this uneven vision for almost my entire adult life, my weak eye suffers from eye strain from time to time.

I don't notice any eye strain. A -1.5 D target theoretically gives peak visual acuity of 1 meter divided by 1.5 or 66 cm (26"). That is about what I have in my near eye. Not sure I would like it in both eyes though. In that case I suspect I would end up wearing progressives full time, just like I did before cataracts and surgery.

Thank you again, Ron!

Thanks, Lynda111, for the suggestion of targeting Intermediate vision. I will certainly discuss it with my surgeon.

Personally I would do the dominant eye first targetted for plano or first minus (-0.25 can still give you 20/20 and has more "safety margin" for not overshooting than aiming for 0.00). Then just see wnat you have after 6 weeks. You might be pleasantly surprised. We can get so hyper focused on IOLs that we forget that the IOL is just one small component of a much larger system. Your cornea actually does 60% of the focusing. How well your range of vision turns out can depend on many things and it can vary a lot from person to person. A bit of astigmatism can give you some near benefit without too much bothersome distortion in overall vision. Pupil size plays a big role too, If you have a small 2mm pupil you might get better near than the next person. Also just the way your brain processes the data can make a difference too. And of course macular health, etc. So many variables. My point is there is always a chance you might get more usable intermediate than you expect even with a monofocal targetted for distance. So I would start there and depending on where it lands you could adapt the plan for the second eye to get a bit more close vision. Some people get intermediate and are very happy with it but there's a reason it is SO rarely done. Studies have shown that most people are happiest with good unaided distance vision.