Just one eye for intermediate monovision - monofocal or Eyhance?
Posted , 9 users are following.
At the beginning of this year, I was on the path to cataract surgery for my right eye but decided to wait because what I was reading online and what my doctor was telling me were two different things. Given this surgery is “once-and-done” I thought it best to take a step back. Now I’m trying to gather and little more information as I consider completing the surgery before the end of the year. I’m hoping you can give me some additional information for a plan forward that I’m still trying to figure out…
I am in my mid-50s with a significant but slow progressing subcapsular cataract in my right eye, which is my dominant eye, and also the eye that naturally sees best at a mid-range distance of 12” to 22”. My left eye is far-sighted and only has minimal cataract which the doctor says may not need replacing for many years. So while I have monovision, I currently wear glasses for computer and woodworking as well as performing music but they can’t correct the vision in my right eye to be able to see clearly enough for those intermediate task due to the cataract, and depending on the lighting situation it can be difficult to read the dash on the car, menus with small type, etc.
Though it would be great to achieve glasses independence from surgery, it is more important to me to experience minimal lens artifacts, so I am currently convinced a monofocal or extended monofocal like Eyhance would be the best match for me. I want to duplicate the intermediate focal distance that I naturally see with my right eye, with the clearest vision at 18-22” distance. My non-dominant left eye would continue to provide distance vision (without surgery). I would be fine with wearing glasses for reading items at a close range (<12”) distance.
The reason I stopped going forward with surgery was:
- the doctor said no mix-n-matching lenses, so if I use Eyhance (or a monofocal) I would need to do both eyes with that same product (presumably for best results), and
- if I use Eyhance I would need to go ahead and do both eyes in short succession
- doctor didn't seem that familiar with Eyhance (but does use Vivity) and didn’t think Eyhance provided a significant benefit over a standard monofocal lens and/or there could be increased artifacts similar to a EDOF lens
- doctor didn’t seem to think Eyhance could (or should, in my case?) be under-corrected for myopia (perhaps because this is my dominant eye?)
All of those were contrary to what I have been reading on this forum!
Hoping to get some clarification here. Thanks!
0 likes, 35 replies
jay3210
Posted
I finally had a followup consultation with my surgeon to move forward with inserting a standard monofocal IOL in my right eye. But i still have a couple questions i'd like to get an opinion about:
The goal is to mimic my eye's current natural ability to see intermediate range, and we agreed on 18" - 20" would be a good target. However, when i asked the surgeon what Diopter he would undercorrect with he said -1.25 (D) and what i've seen on the charts is that -1.5 (D) would be closer to the goal. When i questioned that number, he got defensive so i didn't pursue, knowing that he has done hundreds of these operations and should know what is best and that there may be other factors he is considering to get me to the target focal range. But i still wonder why the difference?
When i asked about my predicted astigmatism outcome he said that astigmatism isn't factored into the target for intermediate range, only for distance. I hadn't read that anywhere, so that took me by surprise. Is it true? (my sphere is -1.5 D my cylinder is -.5 D so i thought an addition -.25 D should get added to my target.)
thanks for your thoughts!
RonAKA jay3210
Posted
For the near eye, I think -1.25 D is kind of the minimum. I would ask what the lens power options are and their outcomes. Try to get him to pick one that is between -1.25 D and -1.5 D. And leave that -0.25 D spherical equivalent from the astigmatism in your back pocket. If you get sphere between -1.25 and -1.5 D with -0.5 D cylinder you should be pretty happy with the vision. Keep in mind there is alway some risk of a miss on the part of a surgeon, but those targets are about as good as it gets.
jay3210 RonAKA
Posted
thank you again 😃
jay3210 RonAKA
Posted
your reply does make me think that astigmatism should always be considered regardless of the vision target distance. correct?
RonAKA jay3210
Posted
Yes. Astigmatism affects both distance and close vision. I notice the astigmatism in my close eye the most.
greg59 jay3210
Edited
Might be a bit late but my 3 weeks of experience with Eyhance (just one eye so far) appears to be better than some defocus curves suggest. In some publications, the left portion of the defocus curve indicates that when you target/achieve -1D with Eyhance, you should see at 20/32 or so at distance. Other publications show the curve to be flatter on the left with 20/32 at -1.5D and very close to 20/20 at -1D. See Figure 2 in BMC Opthamology "A comparison of clinical outcomes and optical performance between monofocal and new monofocal with enhanced intermediate function IOL"
My surgeon hit -0.9D and I see at roughly 20/20 at distance in ideal conditions (J3 reading or functional vision from about 12 inches to infinity). Based on my experience and a few similar cases, the flatter left-side defocus curves might better approximate real world results, especially if you can get rid of astigmatism. Evidently my astigmatism was virtually all removed with limbal relaxing incisions done with a laser. Functional vision from 12 inches to infinity was better than my surgeon expected from the Eyhance but others on this forum have had similar results with -1D targets were achieved.
My personal defocus curve changes with my pupil size with Eyhance (some publications indicate this might not generally be true for all.) At night, I get great vision and contrast sensitivity - way better than anything I've ever experienced (~5mm pupil.) During the day (3mm pupil) I'm roughly 20/20 outside. Right now, I have a bit more need for sunglasses than you might have with a less clear IOL. At dusk or in low light (4mm pupil), I'm probably only 20/30 at distance. Since I can see roughly 20/20 out of my corrected non-IOL eye, it's pretty easy to compare vision in different lighting and I can see better at dusk out of my non-IOL eye but much better at night out of my IOL eye. Given enough time to focus, the eyes are about the same during daylight.
I started with -5D sphere glasses in both eyes along with about -1D astigmatism. Right now, with only one IOL, I'm struggling with extreme monovision and can't really read screens well with both eyes. It takes my IOL eye a few seconds to focus sharply after I close the other eye. Hopefully, that will go away when I get the 2nd IOL in a couple of weeks.
I'm thinking the "crossed" mini-monovision targeting -1.5D to -1.25D for my other eye might be best for me. A bit better near vision. There seems to be very little to gain by targeting better distance vision in the 2nd (dominant) eye but I'd like to be able to walk around without readers. I'll likely have more residual astigmatism (-0.75D or so) from the 2nd eye so I might not get much help either near or far. Even if not, I'll be happy with what I can see out of the first eye and get a pair of prescription sunglasses for driving if necessary. I'll be wearing sunglasses outside most of the time anyway.
I could get a toric to deal with the astigmatism but I'm hoping to get 20-30 years out of the lens. One of the three surgeons I've seen recommended a toric but the others didn't. It's hard to imagine the astigmatism staying relatively constant over that time period. I believe that it should decline slowly over time. If the toric doesn't match my corneal astigmatism fairly closely over time, I can't imagine it doing much good and perhaps could even make correcting with eyeglasses more difficult.
I went with the Eyhance for the advertised high contrast sensitivity and excellent night driving. I'd say it delivered on the claim of 35% better contrast sensitivity than a monofocal at night with a 5mm pupil. It's not that great at dusk or dim light with a 4mm pupil and might have a bit too much contrast during bright sunlight but sunglasses will take care of that.
Overall, I'm extremely happy with the Eyhance so far. As suggested by the above publication, I think it may have a far flatter defocus curve to the left of the peak than many standard monofocals. That allows you to target -1D or -1.5D to gain functional or better near vision with minimal loss of distance vision. If you prefer near vision w/o readers and can get by with functional but not perfect distance vision, this lens could do the job if appropriate targets are achieved.
joan40698 jay3210
Posted
you seem to really understand the numbers which i am somewhat confused about i would appreciate it if you could clarify what they mean my surgeon wants to aim my right eye for -2.25 which she said would enable me to read my iphone without glasses and i believe it is considered near my latest perscription for reading glasses for my right eye is -1.00 so what is -2.25 is it intermediate or near? my left eye eas done 10 months ago for distance and i am satisfied with it i am just having a difficult time understanding what the -2.25 number means
RonAKA joan40698
Posted
A setting of -2.25 is going to give you very good close vision. The degree of myopia or -2.5 D is pretty standard when doing bifocal or progressive glasses. However, when you have bifocal or progressives you selectively use this part of the glasses to see close and then look up to see further away through a different part of the lens. When you do an IOL to -2.25 the whole lens is set to give you that much myopia. You are not going to see well at all in the distance. So when people do the close eye and distance eye trick called monovision they are more likely to select a more modest mini-monovision which is probably ideal at about -1.5 D. This should let you read your phone, use a computer, and watch TV without impacting your distance vision much providing your other eye has good distance vision.
.
The easy way to simulate what it will look like is to get some OTC reading glasses with a +1.5 D power. It is not going to work on your right eye, but putting them on and using your left eye which is set for distance, will convert that eye to -1.5 D of myopia. You could experiment up and down with some +1.25 and +1.75 OTC readers but most will settle for myopia of -1.5 D as a good compromise. I have -1.4 D in my close eye and like it a lot. I am essentially eyeglasses free except for reading very small print in dimmer light. For that I use some +1.25 D OTC readers.
.
Another way to simulate monovision is to see an optometrist and get a contact for your right eye which leaves you at -1.50 D. If it is at -1.0 D now, you would need a contact of +0.5 D to make that simulation. There are issues with this method however. Since your right eye has a natural lens it probably still has some ability to change shape to give you better near vision. This will give you better vision than you will get with a IOL. I did this kind of simulation and liked -1.25 D, but with the IOL lens I find -1.5 D better.