What's new
What's new

OT- Cataract replacement lenses... opinions on Trifocals ?

Milacron

Administrator
Staff member
Joined
Dec 15, 2000
Location
SC, USA
Mostly wondering if a trifocal contact lens would mimic a trifocal cataract lens as a test to see if I liked the concept before committing to the (irreversable) cataract lens.

My current situation is I have a monofocal lens implanted in my left eye years ago but just now needing a lens in the right eye. In a way I have the best of both worlds as I can see 20/20 long distance in left eye (but need reading glasses for close up) and excellent close up vision in right eye (but terrible long distance vision)...so it's tempting to just get a clear lens in the right eye and keep the status quo. Still, might be even better with trifocal in right eye but need to test out the concept first. Thoughts ?
 
Last edited:
I do not think they would be the same. Could be wrong. Ask your doc if a trifocal contact lens is three bands going across or is it concentric circles of different focal lengths.
I got this link in the email today. I am getting daily updates from the "cataract coach". Most are over my head or do not apply to me. I saw my 3rd doctor about my cataract needs this morning and asked him about the cataract coach and this last doctor said he likes "cataract coach" and watches his stuff regularly. The link shows a lens implanted with the concentric circles.
Link https://youtu.be/NebF1xtKf_8
You might look at the J&J Eyhance lens before you make any choices. Sort of a single focal length but with a spot that gives nearer vision. Came close to fitting my needs, but not quite.

Recent thread on PM: https://www.practicalmachinist.com/...ion-choose-396856/?highlight=Cataract+surgery
 
I wonder how a trifocal cataract lens would work.
It sounds like you'd then have a field of vision, where the lower third is for reading, the middle field is for machining and the upper is for driving.
But eyes have a focus point. Using bifocal glasses or even trifocal glasses exploit this by you moving your eyes to select the appropriate optical correction.
Contact lenses, or ultimately cataract lenses cannot do this.
I'd say, that a complete rearrangement of visual processing in your brain is also needed.

But try out the bifocal/trifocal contact lenses. It can't hurt (except your wallet), and let us know.
 
I asked my surgery coordinator about the similarity of trifocal contacts and implants. She said both have concentric circles of focal lengths. Maybe some equivalency for a trial. Myself I am going with the single focal length. Went for my pre-op this morning and they had an opening for Thursday for surgery. Do not have much time to get nervous. After all this waiting it is happening fast.

With 3 circles of light at different focal lengths there will be less light at whatever range you are working at. Watch out for snattlerakes in the dark.
 
I had my surgery 5 weeks ago, single focal length also. It's not much of an event, over real fast. The hardest part is following the rules to not exert yourself until the doc gives the ok. And remembering to put all the drops in faithfully. The difference in vision is astounding, i'm sure you've heard everyone say that. So much more light and color. I'll be doing the second eye as soon as i can afford the downtime.

Hope it goes smoothly for you Fred
 
My wife went with the advanced implants, Poor results. I had the standard Medicare approved cost and continue to wear my trifocals
Happy with the results ! Need glasses in the shop and have been wearing glasses since a teenage , no big deal to me..
 
Pulling up an old thread, but I have a closely related question: how do the trifocal lens implants work? My eye surgeon said they use a grating, but that was the end of the explanation. The grating causes some side effects, like flares around bright lights at night, but my main question is how acuity varies over distance. i.e. would the trifocal lenses be equally sharp when reading a book or looking at a computer monitor or watching TV? Do the three areas where vision is sharpest leave gaps in between where vision is not much improved.
 
Not sure what grating means, but the photos I have seen of the multifocal length lenses show concentric circles of different diopter regions. Each will focus an image on the same region of the retina as I understand it. Your brain will have to determine which more in focus part of the image to pay attention to, none of the different images will have all the available light so your night vision will be not as good. This link has several lens exchanges in showing different techniques:
About 2:25 I see a lens with the multifocal circles being removed to be replaced with another lens probably a single focal length.
I have seen several of this guy's videos where multi focal lenses were replaced with single focal lenses. Reasons go from not being able to see the individual's brain not being able to pick out the desired image to halos and flares at night while driving. My first doctor wanted to use the way more expensive multi focal lenses. I read the manufacturers info before the surgery and saw that night vision would be severely hampered. Again hunting pigs and varmints at night with snattlerakes out there made that a stupid choice. The surgeon I that finally used did my left eye and used a lens that has a bevel around the OD at 5mm. I told him before the surgery I was afraid of that lens because of my excellent night vision. He did not listen and put it in and said afterwards that my pupil would not open wide enough that it would be a problem. He was wrong and it is a problem and I have scarring behind the lens that makes flares while driving at night. he wanted to laser out the scars but that will leave holes in the rear capsular bag that will make an exchange in the future very difficult. If you are already used to bifocal or trifocal glasses, you will probably be better off with a single focal implant and keep the glasses for working at different distances. Whatever you do find a doctor that will LISTEN to your needs and not go with something that makes him more money or that he likes best.

Just to give you an idea of the financial incentive to use the multifocal lenses, if you have them installed the surgeon will charge you about $4500.00 more than Medicare will cover for the lens or lenses. I do not remember if it was each or for a set. I am fairly well set financially so that would not have been a problem if the outcome would have been better, but it is plain stupid to pay that much for what will probably be a worse outcome.
 
Last edited:
I think the doctors said grating referring to refraction grating. And the halo effects are somehow related to light reflecting off corners of the grating.
 
What happened to the double lens implants that came out years ago? Those supposedly used the eye's normal focusing mechanism.

The multi-ring lenses seem like a bad compromise.

I've got to have the left eye done, still, so I'm looking at options. The right has a single focus type.

I'm not, however, sure if mixing types is a good idea. it's bad enough with them being different as it is (one done, one not)
 
I think the adjustable focal length lens that was attached to the focal muscle did not work in practice. i asked about it and it died many years ago because of poor outcomes.

A lot of calculations go into choosing the correct curvature of lens to use. Many times different "powers" are used on the same person for specific needs. I just found this link that I had deleted yesterday, where the author used a multi focal lens in one eye and an Eyehance in the other eye for a doctor.
Most important to get a doctor that listens to your specific needs and will make the calculations for the right lenses.
 
Mostly wondering if a trifocal contact lens would mimic a trifocal cataract lens as a test to see if I liked the concept before committing to the (irreversable) cataract lens.

My current situation is I have a monofocal lens implanted in my left eye years ago but just now needing a lens in the right eye. In a way I have the best of both worlds as I can see 20/20 long distance in left eye (but need reading glasses for close up) and excellent close up vision in right eye (but terrible long distance vision)...so it's tempting to just get a clear lens in the right eye and keep the status quo. Still, might be even better with trifocal in right eye but need to test out the concept first. Thoughts ?

By trifocal do you mean diffractive plus refractive? Anyway, here is the link to an explanation of the differences, used for marketing to hurried doctors.

I don't know that I would go for mis-matched lenses in the two eyes. Some people can adjust, many cannot.

https://us.alconscience.com/sites/g...ing-IOLs-An-Optical-Lesson-US-REF-1900001.pdf
 
I should explain how refractive plus diffractive (wave interference also used) implanted lenses work.

Start with a single-focus implantable lens and engrave one surface with a set of ~ circular grooves in a complicated pattern intended to diffract some of the light to focus somewhat nearer than the refractive focus, and some to focus somewhat farther away than the refractive focus.

Whatever the person is trying to look at will be seen best, and the other focuses will be ignored by the visual centers of the brain. (We do assume possession of a functional brain.)

That's the theory, anyway. But many people cannot ignore the currently disfavored foci, and end up with confusing scenes, especially when driving at night, especially if it's raining.
 
I had the trifocal lenses installed, the second one two weeks ago. My initial reaction is that there are many situations in a machine shop where the second image makes it difficult to do the job. E.g. measuring using a steel rule, the second image lines right up with the next mark on the rule. Depending on the lighting, the second image may be just as strong as the first, in a high contrast situation. OTOH, I can easily read small print and I don’t need glasses for TV, in those situations the eye compensates and you don‘t notice so much.
 








 
Back
Top