Where can you find defocus curves?
Posted , 4 users are following.
The surgeon I've talked to has recommended Alcon monofocal lenses. The only "defocus curve" I've been able to find online is on Alcon's website with a discussion of the lens, and the curve has a disclaimer that it's simulated for "illustrative purposes only." (RonAKA has also kindly submitted a graph that I will be digging into shortly.) So where can I find the "official" defocus curve? Is it something the layman can access?
On a lighter note, I've been seeing the diamond eye issue with Alcon lenses discussed a few places. My understanding is that it's cosmetic, so not an issue and could be a source of endless entertainment. Found a photo someone posted showing the effect, and my husband said "It looks like the Westworld robot eye (Yul Brenner version.) So my sweetie will be a robot--I hope for good and not for evil." Heh heh heh--I intend to go full evil robot on him if it ever happens.
0 likes, 6 replies
RonAKA lucy24197
Posted
You can find the defocus curve of the monofocal in the Vivity information. They use the standard lens as a comparison to show the extended range of focus of the Vivity compared to the standard lens. The SN60WF is the Alcon AcrySof IQ Aspheric monofocal lens, and the lens I have in my right eye now.
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Google this phrase to find a presentation on the Vivity and see page 11 for the Defocus Curve comparison.
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Clinical Outcomes of a Novel Non-Diffractive Extended Vision IOL CATHLEEN MCCABE, MD
lucy24197 RonAKA
Posted
Oh, that helps tremendously. The curve is a lot flatter than the "simulated" curve in the online description of the lens. Gives me help that there might be a reasonable outcome in all this.
RonAKA lucy24197
Posted
Yes, I think sometimes cataract patients get the impression that they will be totally blind up close with a monofocal lens, and that intermediate vision is somewhere around 6 feet or so. The monofocal does very well at 6 feet and only start to get less crisp at 2 feet or possibly a little less. It is really no different that presbyopia due to ageing. The artificial IOL has no accommodation just like an older eye loses accommodation ability.
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The flatness of the defocus curve is important. As you can see from the curve you get the same 20/20 (0.00 LogMAR) visual acuity for distance if you are at -0.25 or +0.25. Where it makes a big impact is on your close vision whether you are at -0.25 or +0.25. A miss by the surgeon on the + side significantly hurts close vision, where a "miss" on the - side is a help to near vision. A miss with the Vivity is even more impactful as the curve is flatter still. That may be the reason that there is quite a bit of variability in the satisfaction with the Vivity. A miss with the Vivity to the + side would make a significant reduction in reading ability.
bob38868 lucy24197
Posted
As I mentioned in a previous post, I ended up +.25 dominant and -.25 non-dominate with the Eyhance lens. I'm 20/15 distance both eyes however even though the intermediate is very good...the world of inside the house is so much better with my +.5 glass lens readers on. Food prep is clearer, the laptop is very clear, my iPhone is easy to read and text with and the small text street names on my Chevy Volt navigation screen are easier to read at night. Very little in distance detail is given up when wearing the readers. Turning the readers sideways so just the non-dominate eye gets the extra +.5 (making it .75 myopic) gives me the same near detail and retains the distance focus. It is amazing how such a small amount of correction can affect functional vision when one looses the muscle accommodating lens. The .5 of micro mono-vision is helpful however 1 would be much more useful in this case. I would suspect it would need to be 1.5 or better with a standard mono-focus lens.
My near might have been better if I would have retained some of my astigmatism however the toric lens corrected it so well letters are extremely sharp on screens and pages with no haze or fuzz. Its the best vision of my life.
The only hassle so far has been when I try to work on something that requires an strange head angle and closeness where even the 1.5s I have don't work well as I either need to look over or under them. Progressives have more of a problem as they have a limited sweet spot...not sure what to do.
lucy24197 bob38868
Posted
I hear you about head angles. I only wear glasses for driving, so with my near/far eye combo, my problem now is if the cats knock something under the couch or if I'm looking through a deep gap--like between the side of the refrigerator and the wall--I have to approach it from the side of the "correct" eye so I can focus on things. I invariably guess wrong as to whether I need near or far with things under the couch, so it's lie on the floor, peek under the couch one-eyed, say many dirty words, stand up and lie down the in other direction so I can see what I'm looking at with the other eye.
Night-Hawk bob38868
Posted
The new Tecnis Eyhance Toric II IOL info looks great!
Thats now my top choice for whenever I need cataract surgery in my left eye which has about 2.0d astigmatism.
I might plan to target it with a slight -0.5 to -0.75D nearsight after astigmatism corrected for mini monovision to at least get me good computer monitor and smartphone intermediate vision as well as decent distance vision, to go with my right eye that has a Tecnis toric monofocal that gives me about 20/25 distance vision (has a small residual astigmatism <1d, so correction only need to get better than 20/20)