Replacement Eyeballs!

[AtomKraft]

Well, "a friend of mine" has a cataract in one peeper.

His local eye hosp offered to stick in a multifocal lens that will apparantly work fine at distance, but close up too.

His other eye is 6/6.

He is a Class one holder.

What to do for best?

[ShyTorque]

Strange how many "friends" have problems....

EASA allow single focus lenses only, with corrective specs.

From the CAA website:

2. Cataract Surgery

The assessment of individuals following cataract surgery should be done on a case by case basis. This should take into account clinical evidence on recovery times and outcomes from modern day surgery. A pilot can be assessed as fit following cataract surgery from 6 weeks post-operatively.
A report shall be provided from the consultant ophthalmologist who performed the procedure and should include the date of surgery and type of implant used, details of distance and near visual acuities, any post-operative complications, confirmation that the pilot has fully recovered from surgery and that there is no significant photophobia, glare or diplopia.
Note: multifocal and bifocal implants are NOT compatible with certification. Monovision is not recommended and pilot would require well-tolerated multifocal spectacles in order to meet the distance and near vision standards. Accommodating lenses may be acceptable following a review with a consultant aviation ophthalmology adviser.
For Class 1 pilots, an operational multi-crew limitation (OML) may be appropriate if there is evidence of co-morbid disease or procedure or complication that may increase the risk of visual incapacitation.

[Loose rivets]

Go for a fixed length which is at infinity in layman's terms. Some folk like one for close-up but to me the idea is a bit :ouch:

Following my vitrectomy and peel, I'm now going into the cataract phase having enjoyed 20/20 in both eyes for some months. Bloody tedious. Went through it all with the other eye some years ago, though I didn't have a peel! The cataract was more stressful than the vitrectomy but settled down in time and gives me bottom line with a little cylinder correction. No need for glasses most of the time.

Just for general interest, the post-vitrectomy cataract seems to always be the nuclear type. The quite bizarre effects come from the brain as it kind of multi-lenses in a frustrated attempt to look around an obscured central point - switching at high speed from one optic route to another.

I was fascinated by this during the first op., but can't find the data on this phenomenon this time around. That it happens is not that surprising I suppose as the change of 3D viewpoint timing on the wire frame cube is the same in most humans though much, much slower of course.

Here's a thing. I was disappointed I needed any correction at long distance but soon realized the astigmatism was the same as before the op. I conclude the cylinder distortion must be caused by the cornea.

I'm still a bit concerned about the risk-factor for LASIC, though the technology has improved enormously over the years since a surgeon told me that, In the UK, no eye surgeon or any member of their family, has had LASIC.

[ShyTorque]

Atom K, there's a p.m. for you.

[MarcK]

I think there is a difference between multifocal lenses (like transition eyeglass lenses) and accommodating lenses, that actually change shape to focus at different distances.

[pax britanica]

My wife who has had to wear ahrd contacts from 16-60 had her 'eyes'replaced last year by a Prof of Optical Surgury at Moorfields. In her case the front of the lenses was delaminating sue to hard contacts use and had incipient cataract in one eye.

In practice the surgeon replaces both natural lenses with artificial toric lenses -toric lenses allow focussing at different lengths in the same way toric antenna can receive many different frequencies simultaneously.

Made an incredible difference from virtually legally blind without lenses to somethinga bit below 20 20. but as Isay she was startiing froma very bad baseline.

Prof also made the point that yes do not work as most people think and that there is a great deal of 'signal processing ' done in the brain to interpret what the eye receives and not all of this is wholly understood but stated earlier the effects are that the brain can correct the images you 'see' by interpreting the data it receives from the eyes . In suitable terms for this site eyes do not work like a basic radar system but like one with complex signal processors that give an improved 'picture'

This si still fairly new treatment in Uk so you may need to consider that but while I do not know the legalities as regards licences it is remarkable treatment that can produce spectacular results-life changing in wifeys case

[ShyTorque]

The information needed by Atomkraft is in my reply at post #2.

The CAA have to be informed. The pilot's medical certificate is temporarily suspended. The CAA subsequent require a detailed report from the consultant surgeon, including the type of lens used. As I understand it, having the wrong type of lens inserted could cause permanent suspension of the medical. End of aviation career.

[mothminor]

I`m in a similar position.
I have a slowly growing cataract in my left eye and have soon to decide which replacement lens to have fitted.


I will go for single focus lens (distance) and am interested to hear from others experience as to how close to 20/20 did their surgeon manage.


Also anyone had one of the light adjustable lenses (adjusted by uv light to fine tune lens after fitting).


Best
J.J.

[Loose rivets]

Why would they suggest such a thing? Your iris should still work perfectly.


I think the thing about deciding on a distance has a lot to do with age. A lot of oldies find their focal distance goes out and out as they get older. Mine went past infinity. Just. Wearing reading glasses is just part of life and since I do lots of tekkie things like repair watches, I'm swapping them on a regular basis.

The little things that stretch the original lens work opposite to the way many people think. Trying to improve vision by exercise is like pushing a piece of string.

The American surgeon that did my left eye tried very hard to get it perfect for me. They even bought out a magnificent bit of old kit that measured the lens to retina distance. I panicked a bit when it was first uncovered but it settled down okay. Again, I'll mention the original astigmatism remained. That was disappointing but hardly noticeable and no one's fault..
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[MarcK]

When I had my left eye done, single focus was the best technology. I came home with 20/15 (6/4.8) vision in that eye, gradually (3 years) now down to 20/25 (6/7.5). Right eye, when I need it, will probably get a newer lens type.

[AtomKraft]

I'm also not sure about 'accomodating' lenses, and their legality.

I've tried multifocal specs before, and they were a PITA
. These specs had various zones with different correction. So, you could look straight ahead through the part of the glass which corrected for distance, or look down and find yourself looking through a bit of the same glass which had a correction for reading. Ive seen ones which blended the areas of diffeent correction, and others that had sharply defined boundaries. Anyway, no likey.

The 'multifocal' intraocular lenses that 'my chum' is looking at have only one area of correction. There is no 'zone for reading' and 'zone for distance'.

Instead the offer seems to be that the artificial lens actually refocuses as you change from looking at distance, to say, reading.

This seems implausible to me as the new artificial lens would need somehow to physically change shape in response to the direction of ones gaze.

Can this be true?

They promise correction for distance, and no need for reading glasses.

Sounds too good to be true! Anybody got these???

[Loose rivets]

This gives a lot of information but I'm perplexed by the way round they describe the cilia forces.


Crystalens - Pros and Cons of Accommodating IOLs (http://www.allaboutvision.com/conditions/accommodating-iols.htm)


Ah, just reread it. I've made that mistake before. Don't confuse the muscle (singular) with the cilary zonules. They are relaxed counter-intuitively.

The lens and ciliary muscle are connected by a 360-degree series of fibers (called ciliary zonules) that extend from the ciliary muscle to the thin lens capsule (or "bag") that encloses the lens. The ciliary muscle, ciliary zonules and lens capsule keep the lens suspended in its proper position inside the eye for clear vision.

In a normal eye (without presbyopia or cataracts), this dynamic process of accommodation adjusts the focusing power of the eye by changing the thickness of the eye's natural lens.

But:

When the ciliary muscle is relaxed, the lens flattens to enable clear distance vision. When the ciliary muscle contracts, the lens thickens, becoming more curved for added magnification for clear near vision.

One is still suspicious and is searching further about this.

Ah, Okay. All is explained.

http://www.yorku.ca/eye/ciliary.htm

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:( Grrrrrrr to Edit thingies.

[oldpax]

Not a pilot but I had my eyes done here in Thailand ,right eye was 70%cataract and the left eye was just beginning to show so I had both eyes done .Interlocular lenses inserted after the bad lenses were sucked out!!Difference was amazing !However at night I still get a bit of spider web on lights but I can live with that .Procedure was painless and took about 15 minutes per eye(5 days apart!)

[Loose rivets]

There have been some worrying tales about poor results in the UK. My first one was a tad shy of perfection for the reason I stated but when I heard some of the correction needed after some UK ops I was very glad to be where I was. (in both senses.)

Worried I'd muddled the issue, I phoned a friend.

Yes. The ciliary muscle is like a torus surrounding the lens, and attached to it by means of radial filaments. Muscles cannot extend or expand, they can only contract, and the ciliary muscle is no exception. The lens "wants" to be thick to have a short focal length. When the ciliary muscle is relaxed it pulls on the radial filaments and flattens the lens, and thus increases the focal length. Contracting the ciliary muscle allows the lens to get thicker and focus on near objects.
With age, the lens tends to lose it's ability to recover its "thick" shape, so you cannot focus on close objects.

You can see how this goes against old concepts and why the aged tome (something like) 'Better sight without glasses' is based on muddled thinking.

That book has been going so long you have to interpret the 'old English' a lot of the time.

[mothminor]

ShyTorque - thanks for the pm.


It`s very difficult to get information on any residual refractive error after cataract surgery.


The Royal College of Ophthalmologists guidelines state that the expected level of accuracy of biometry is a postoperative spherical refractive error of no more than ± 1 dioptre in at least 85% of patients - potentially quite an error!
Also that the nhs do not routinely follow up patients to asses any residual refractive error.


Any more experiences, good or less so?


J.J.

[G0ULI]

Had a vitrectomy last year after a retinal tear caused by a blow to the head. Within three months a cataract started to develop. It progressed fairly rapidly to the point where I had the ability to focus on fine detail at a distance of a few inches, but anything more distant was a blur.

A couple of months ago the cataract was removed and the natural lens replaced with a single focus distance biased lens. Remarkably, I found that while I now had perfect distance vision, I could also bring the eye to focus well enough to read without glasses in reasonable light. So I now have 20/20 vision in both eyes and am free to drive or carry out other activities without needing to wear glasses. Weird after 30 years of automatically slipping a pair of glasses on every time I drove. The improved vision in the treated eye seems to have dragged up the performance of the slightly myopic untreated eye. Quite amazing.

The NHS were brilliant, no complaints. I had to wait a few weeks for an appointment for treatment, but it was all done for free. The operation is painless, but the intensity of the lights used by the surgeon can be uncomfortable. You knew there had to be a catch? ;-)