Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

The Lounge A place to talk about almost anything but politics and religion.

Eyesight thread
Eyesight thread
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th December 2018, 07:04 AM   #1
Steve Luck is offline Steve Luck  New Zealand
diyAudio Member
 
Join Date: Sep 2012
Location: Wellington
Default Eyesight thread

As requested to move this away from the more serious health thread.

An explanation on what's been done to my eyes and how it works:

Rapidly developing cataracts in both eyes have left no choice for me(at present) other than to have both the lenses I was born with removed and replaced with man made lenses. Technology first developed when an English eye surgeon noted that a spitfire pilot with acrylic splinters in his eyes from his canopy could tolerate them without the body reacting to them.

Move on a few decades and the original lenses in my eyes where broken up with me fully conscious but numbed up using a ultrasonic probe under 2mm across. They suck it out and then insert a new rolled up lens through the same hole. Under body temperature it straightens out slowly enough not to cause damage to the eye.

In my case the new lenses are specified to correct the astigmatism I've got(front of of your eye isn't quite as round or is too round). Having carefully mapped my eyeball before they started they line up a couple of horizontal lines on the lenses (now inside your eye) with Inked lines placed on the surface of your eyeball and with images projected through the microscope the surgeon uses. Provided the lens doesn't move too much after surgery the astigmatism is almost wiped out.

Here's where the confusion starts - there are lots of different lenses by different manufacturers and some use the same buzzwords but work in different ways. There are lenses that are multifocal in that they project multipe different images on the back of your eye in different places that your brain can choose from. Think of lots of donut shapes for some lenses. Contrary to what you might think your brain doesn't need an image like a pinhole camera for you to see properly. It's more like a big CCD that can pick just the right pixels to assemble to make a focused picture.

The lenses in my eyes look more like bifocals than the donut rings seen on on some brands but like some of the donut variety claim the name EDOF extended depth of field.

In my case the theory was to set up my left eye with a lens that covers from newspaper/computer screen reading distance into the distance for pretty average vision (nothing bionic you understand) and the right eye just slightly shorter than that to cover finer print but not quite so far into the distance. I asked to be able to get the soldering iron out without glasses if possible. If i need to see mountain goats a couple miles away I'll get some binoculars out. You can swap this around though apparently pilots and golf players are happier with great distance vision and wearing glasses for most reading.

For me this creates a big overlap between the eyes with no compromise for the stuff i do everyday. But your brain can use the input from each eye to adjust the picture from the other. So with both eyes open I now have very good vision from fine print out to the pines on the hilltops in the distance. This method can still leave some patients needing reading glasses for very fine print. The advantage is that by not trying to guarantee I would be free from glasses for reading tiny print they can use lenses that almost eliminate the chances of problems with glare and halos from bright lights during the day or night time driving associated with some brands of multifocals.

Anyway for me it's working very well with eyesight better than I've had since my twenties (I was Fifty in July).

Hers some links:

YouTube

YouTube
  Reply With Quote
Old 17th December 2018, 05:40 PM   #2
tsmith1315 is offline tsmith1315  United States
diyAudio Member
 
tsmith1315's Avatar
 
Join Date: Jul 2003
Location: Doerun, GA
Steve, that's a great readable synopsis of cataract surgery.

Quote:
Originally Posted by Steve Luck View Post
Here's where the confusion starts -
No confusion here. From the other thread:

Quote:
Originally Posted by Steve Luck View Post
Definitely not monovision (snip)
True.

But it's not exactly stereo vision either, with one eye not best corrected at distance.

That's why we refer to it as a modified mono. Just semantics. We also do it with contact lenses using multifocals, or one multifocal & one monofocal lens, or one multifocal and one naked eyeball.

Every patient is different and the amount of disparity they need and can tolerate varies with task, biology, and even personality. It can be quite a balancing act.

Your surgeon did an excellent analysis of your corneal astigmatism via corneal topography. We also use that to fit specialty contacts, primarily rigid gas perms, keratoconus lenses, and therapeutic lenses that offer an alternative to refractive surgery.

From what I see, the Lentis Comfort IOL's are aspheric implants designed for stereo distance vision with a 1.50D bifocal segment for intermediate vision. Most of the add powers I normally see are 2.00 and 3.00. Yours are toric as well to correct the corneal astigmatism. The surgeon went beyond that and selected a slightly more positive central vision power in the non-dominant eye, so that combined with the 1.50D segment, you would able to see at soldering distance. That increase is counterproductive for distance vision, and must be carefully balanced for your particular needs.

Besides precise, your surgeon is obviously very careful and intuitive to manage this balancing act with IOL's. It's trying enough to do it with contacts!



Quote:
Originally Posted by Steve Luck View Post
Anyway for me it's working very well with eyesight better than I've had since my twenties (I was Fifty in July).
And that's all that matters in the end. Most folks don't end up quite that well off, so it's fantastic that it has worked out so well for you.

I'm glad your year is ending on a high note!
__________________
Tim

Last edited by tsmith1315; 17th December 2018 at 05:58 PM.
  Reply With Quote
Old 17th December 2018, 06:06 PM   #3
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Eyesight thread
Thanx for this. I have cataract surgeries next summer. I have some vision issues caused by lack of oxygen to the eye during my life-saving operation 1 and half years back.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 17th December 2018, 06:07 PM   #4
Cal Weldon is offline Cal Weldon  Canada
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
Eyesight thread
Good to hear Steve. Being someone who had laser surgery to correct myopia and astigmatism back in 1993, I can appreciate how wonderful good vision is. While mine was nothing compared with yours, I am still very happy with it and am corrective lens free to this day. I am now 56 years old.
__________________
Cal Weldon Consulting.
http://www.calweldonconsulting.ca/
  Reply With Quote
Old 17th December 2018, 06:47 PM   #5
tapestryofsound is offline tapestryofsound  Scotland
diyAudio Member
 
Join Date: Jul 2017
Thank you Steve for this need to know information.

I cleaned up my act 10 years ago. I am now an über-healthy 63 and intending to live to 120 - so much to do, so much to see! My health in every respect has become vital - especially my sight and hearing.

I am so glad you got the very best treatment available.

ToS
  Reply With Quote
Old 17th December 2018, 07:08 PM   #6
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
Steve, that's a really interesting and informative post, and you sound content with the solution. Do you drive? If so, how does it seem?
When I close one eye on the road, it seems scary, but maybe you don't need a focused image for stereoscopic vision?
  Reply With Quote
Old 17th December 2018, 07:32 PM   #7
nezbleu is offline nezbleu  Canada
diyAudio Member
 
nezbleu's Avatar
 
Join Date: Dec 2009
Location: Halifax, Nova Scotia, Canada
Eyesight thread
I will be having a new lens in my left eye next month. The cataract on that lens has gotten pretty bad in the last couple of years. Unfortunately I have another problem with that eye, a large "floater" in the back of the eye. I gather there is some sort of membrane inside the eye which can break down and detach, and there is a big piece of it floating around inside my eye. sometimes it is edge-on and not too obtrusive, but other times it is like a large dark patch in the middle of my vision. I am concerned that the cataract surgery won't help with that, and the result will be a clear lens that I can't always see through.
__________________
"In the world of commerce and finance it is thought quite remarkable if a man is both clever and honest." -- Demosthenes
  Reply With Quote
Old 18th December 2018, 01:52 AM   #8
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Response originally to tsmith1315 in other thread

> getting most folks to purchase a task-specific pair of glasses is nearly impossible.

Well, maybe I've been frustrated since my accommodation faded. Part of my back-problem is straining to read a CRT (the first symptom was inability to read a calculator). For a decade I had "work bifocals": bottom around 1.5add to see the screen, top a half-D shy to see across the room and walk around a familiar campus. When I went to the parking lot I went back for the driving glasses. (Not essential, even legally, just more comfortable beyond 20 feet.)

ALSO..... I am comfortable paying $7 for single-vision spectacles.

SPH CYL Axis
0.00 -0.50 80
+0.25 -0.75 95
Frame Price $6.95
Lens 1.50 Standard Single Vision FREE
Standard Shipping ... $4.95

I'd forgot the 3/4d astig in one eye; that's why I prefer prescribed over plain readers for PC, and how I know Zenni read the Rx correctly.

> Steve's "modified monovision"...

I was trying to figure that out. In my exam there was some discussion about putting me as-I-was, or making me "normal". I mulled and opted to be "normal" (good at infinity, readers for reading), K.I.S.S., all my friends do it. Doc was pleased. No discussion of multiple zones in different eyes. (And they already knew my insurance would cover the basics well; and I just-might pay for extras.)

So Steve got four different focal points? His eye/brain learns which eye and angle to use for the distance? Monocular he usually has a pretty sharp image in one eye; the brain discounts the other eye. In stereo he has one sharp and one fuzzy, which may well be ample for all everyday reach out and grab stereolocation.

> ...progressive multifocal lenses...

That stuff blows my little mind. The aberrations would seem to be atrocious, also annoying. That they are widely accepted means math far above the old optics books (or hand computation!). And as you say, cutting those insane curves.

> virtually no one listens to us professionals about this until it's too late.

Yeah, well, ashamed to say, while I have not yet poked an eye out, I used my New Eyes to arc-weld with a faulty helmet. I gave up quick, but not quick enough. Stars and dim lights I see off-axis can not be seen on axis: retina burn. I suspect this will show in my next eye-exam, the doc will be disappointed in me.
______________________

I posted a detailed tale on another forum, which some folks felt was helpful. If that forum is not Public, tell me, I'll copy it here.

Last edited by PRR; 18th December 2018 at 01:59 AM.
  Reply With Quote
Old 18th December 2018, 03:09 AM   #9
phase is offline phase  United States
diyAudio Member
 
Join Date: Oct 2004
Thanks for the details, gives me some hope!
  Reply With Quote
Old 18th December 2018, 04:54 AM   #10
tsmith1315 is offline tsmith1315  United States
diyAudio Member
 
tsmith1315's Avatar
 
Join Date: Jul 2003
Location: Doerun, GA
Quote:
Originally Posted by PRR View Post
For a decade I had "work bifocals": bottom around 1.5add to see the screen, top a half-D shy to see across the room and walk around a familiar campus.
This is the premise of computer/workstation/work area progressives. They are designed backwards, that is to say they give priority to the near vision area at bottom and work up the progressive channel/computer area as a vertical power digression.

Quote:
Originally Posted by PRR View Post
ALSO..... I am comfortable paying $7 for single-vision spectacles.
Comparable to cheap kits on ebay. As a licensed professional, if I did in our office some of what they do, I'd be prosecuted by our state board.

Quote:
Originally Posted by PRR View Post
So Steve got four different focal points?
Pretty much, and that's a great interpretation as to how they work together.
The brain is fabulously adaptive.

Quote:
Originally Posted by PRR View Post
That stuff blows my little mind. The aberrations would seem to be atrocious, also annoying. That they are widely accepted means math far above the old optics books (or hand computation!). And as you say, cutting those insane curves.
Yeah, 25 years ago, I could estimate the needed curves (all 2 of them) pretty doggone close in my head. There were a couple of times when I actually had to do it, either a computer down or the particular lens out of range for our system and didn't bother to use pencil or paper.
Now the multifocal powers are integrated into the distance Rx and the whole thing is cut onto the back surface. The lens area is divided up into thousands of different "points" and Rx can be optimized for angle & distance from the back surface of the lens to the eye, material index, frame fitting parameters, add power, etc for each point with iterative processes to refine the end result. In at least one design, hundreds of thousands of iterative calculations are performed for every Rx submitted.
Aberrations/unwanted astigmatism were atrocious and when I started 25 years ago, 50% adaptation rate was what I saw. With the new products, I think we had 3 non-adapts this year.

We're not going to talk about the welding incident.
__________________
Tim
  Reply With Quote

Reply


Eyesight threadHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Suggest add "Unsubscribe this thread" to Thread Tools Tromperie Forum Problems 4 5th May 2018 08:08 AM
How to change thread title or delete thread in Swap Meet tubesguy Forum Problems 3 11th March 2017 03:32 PM
Should a person who starts a thread have quasi moderator status on their own thread? erin The Lounge 15 23rd October 2012 11:41 PM
Editing thread first post title doesn't change actual thread title muckrake Forum Problems 2 15th August 2012 11:13 PM


New To Site? Need Help?

All times are GMT. The time now is 05:04 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki