Ever since I can remember, I’ve been substantially myopic or short sighted. As a child, I would lie awake at night waiting for any kind of night-time creature to emerge from the blur and eat me, before I had a chance to see it and run. But luckily, when wearing the prescribed lenses, my corrected visual acuity has always been on the better side of average. This has meant that I’m quite acutely aware of what good sight look like, and what it looks like when it is bad.
Growing up, I remember each new prescription would snap the twigs in distant trees back into my consciousness. Something that most people walking around blissfully with uncorrected vision would never perceive.
So for the past 40 years, I’d woken up, put on my glasses, lived an entire life, removed my glasses, and gone back to sleep. But sadly, last year, something changed. I contracted the dreaded presbyopia disease. Presbyopia is not really a disease. But it is a sure sign that I was getting old. Really old. Old enough that for the first time in my life I needed to have reading glasses, as well as normal distance glasses. This is a major problem, as I was always walking around with the wrong glasses on my face.
So why not bifocal lenses, or for that matter graduated progressive or multi-focal lenses? Well for me it comes down to visual acuity. I am not at all happy to have parts of my vision obscured, and need to look at people down my nose, or whatever is needed to get the small piece of corrected vision between me and the object of interest. So, I needed a viable solution.
I’ve written here about obtaining my personal cyber eyes because there are plenty of medical reports and advertorial information sources out there, speaking highly of the outcomes. But, not very many individuals have actually written about their own experience of vision enhancement.
PRK or LASIK
For some time I’ve considered, and discarded, the idea of PRK or LASIK as being “a bit of a bodge” at best, and a long term science experiment at worst. In my view, scarring the cornea to adjust the optical characteristics of an optical device with a lens just seems in every way wrong headed. Adjusting the lens characteristics should be the essence of the solution. Reports of the reduction in dilated low-contrast visual acuity (i.e. the nighttime) from LASIK do not reduce my perception that it is a bodge.
Perhaps 15 years ago I considered the idea of getting intraocular lenses which, although being very expensive, seemed like the right way to solve my problem of myopia, with no other vision issues. So 6 months ago with this resolution in mind, off to the surgeon I went.
Intraocular Lens (IOL)
Following a very short discussion, the surgeon disqualified me as a candidate for the intraocular lens (IOL) procedure. This relates back to the original reason why I presented, being presbyopia. Simply put, there is no reason place an auxiliary lens adjacent to an old immobile human lens. For younger people the IOL is IMHO the right way to go, to preserve all of the options for future surgical advancement. But, there is another procedure that is prescribed for older presbyoptic myopia suffers, like me.
Cataract or Clear Lens Replacement (CLR)
Once you have the onset of presbyopia, then there is little that can be done with the existing human eye lens. Because of weakness in the muscles of the eye, it becomes a fixed focal distance device, that suffers from UV aging, and degeneration. At a certain age, most (all) people begin to suffer from changes to the lens through clouding, which is termed cataract. The signs of cataract development can be detected from when you’re about 50 in most people, although the symptoms in vision may not be apparent for another 15 to 20 years.
Following up on the discussion with my surgeon, his team had found the indication of impending cataract in my lenses. This means that at some stage within the next 20 years I would need to have cataract operations to correct my vision. So the question was simply, when?
Coincidentally, the conversation I was having at that point was around Clear Lens Replacement, which is a cosmetic surgery undertaken to remediate the vision of people without the signs of lens degeneration and cataracts. The surgical procedure for Clear Lens Replacement and Cataract Removal is identical (for all intents and purposes, noting I’m not an optical surgeon and there are certainly things I don’t know about).
The procedure consists of making a small 1.5mm to 2mm long slice in the edge of the cornea, with the iris fully dilated. The surgeon then slices up the old lens, and vacuums it out of the lens pouch. He then injects a self unfurling lens through the slit and tucks the edges safely under the iris. The operation takes about 20 minutes under strong sedation, and is not accompanied by any pain, or even discomfort (in my case).
Waking up from the snooze, it is incredible to actually see things sharply, though everything is clouded and somewhat unstable. Later it became obvious that the blur was mainly caused by the plastic pirate eye-patch I got to wear home (and at nights for a week).
In my case, it took nearly 3 days before the iris dilating drugs wore off, and my eye could function properly in the presence of strong light. This issue led to two symptoms. Initially my iris was so dilated that stray light was entering the optical pathway, and causing “lens flare”. Later, there was just a sensitivity to outside light intensity. By the 4th day this effect had worn off, and my vision was pretty much perfect.
The interim two weeks with just one eye corrected were quite difficult. My eyes had nearly 4 dioptre difference in prescription, and the eye with the stronger prescription was operated on first. I tried to use my normal glasses with one lens popped out. This meant that that my brain had to accommodate an 8 dioptre change in retinal image size in my corrected eye with the image presented by the uncorrected eye, to be able to integrate binocular vision. Basically, I couldn’t do it. So for reading I used a piece of cardboard in my reading glasses to obscure sight in my corrected eye, and for outdoors I just left my uncorrected eye to fend for itself. Possibly using a contact lens in the uncorrected eye may work if needed, as a contact lens impacts the retinal image size to a much lesser degree than glasses.
Well it is now one month since my first operation, and two weeks since my second. And I have to report that the procedure was a success. My visual acuity is sufficiently high that I don’t need any distance correction. I can read two lines below the 6/6 (or 20/20 in Imperial) which is the equivalent of 6/4, the vision of a young person.
My surgeon was aiming for -0.25 dioptre in both eyes, as the margin for error from the mechanical calculation is 0.5 dioptre. Better surgeons will use their experience to temper the calculation and prescription and have a higher chance of getting a good outcome. My right eye (after two months) has settled down from -0.5 immediately after surgery to -0.25 dioptre. My left eye is at +0.25 after a month, and its resolving capability has been slightly improved. This is a very good outcome, and the surgeon is very happy with himself.
So how do my eyes work in the short range with effectively a fixed focus? Well this was the big question that I was worried about before this whole endeavour. Would I be able to see the speedometer whilst driving? Could I read my wristwatch, or see my phone? Well there the answer is mostly, yes. It is amazing (to me at least) how closely the human eye resembles a pinhole camera in practice, and doesn’t need to be actively focused. Although, there is no escaping the need to use reading glasses for detailed close work.
My eyes had quite different prescriptions, so my surgeon installed products of quite different types, from different manufacturers. I’m sure my experience is not typical so I’ll note down the issues I’ve seen over the past few weeks.Right eye was corrected for substantial myopia, with a PhysIOL MicroPure aspheric lens with a square edge. The square edge is to prevent the regrowth of lens cells from interfering with the replacement lens surface.
I find this square edge causes total internal reflection and halo effects in darkness with strongly off centre lighting. An example of the issue is down-lighting in a lift. I’m told this halo effect will disappear within 6 months, as the eye assimilates the lens (I presume), and reduces the interface TIR effect.Left eye was corrected for astigmatism and myopia, with a Zeiss AT Torbi 709M toric lens. The lens is very comfortable and doesn’t have the same reflection issues as the right eye, but potentially I’ll have to watch for regrowth of human lens cells which would obscure my vision.
An acquaintance experienced cell regrowth. He noticed cling wrap being layered across his vision from about 20 months post operation. The resolution is to blast the regrowing lens cells with a femtosecond laser to burn them away. This is done in the surgeon’s chair. During the original operation some human lens cells are left to support the new lenses in a pocket, but after the new lens has been grown or scarred into place, these old cells can be safely blasted out of the way. Vision is actually improved by removing them entirely.
Within 24 hours of left eye operation, I noticed a colour perception effect, where my left eye was seeing colours much (somewhat) colder than my right eye. A bit like the difference between a daylight globe and a warm-white globe. I was worried I was “seeing things.” It was only after I obtained the technical details of the lenses the surgeon had used, it became clear that the right eye has a UV and blue light filtered lens, but the left eye lens is unfiltered.
There is no clear preference among surgeons as to which is better, with unfiltered vision potentially leading to better sleep, but blue filtered vision being more closely aligned to young vision. I actually prefer my cold eye colours, but I also prefer daylight globes in my home. In normal daily binocular vision, there is no discrepancy to speak of. In all cases, sunglasses are recommended for outdoor vision, anyway.
One of the goals for this procedure was to enable me to use $5 supermarket reading glasses, and not be bound to special prescription lenses. In fact, that is the outcome I’ve obtained.
There is a handy formula or hack that my surgeon disclosed. The dioptre measurement on the supermarket readers is equivalent to the inverse of the focal distance at which they work best (assuming you’re perfect at infinity, which I am now). So a +1 dioptre lens will focus at 1/1 metres. A +3 dioptre lens will focus at 1/3 metres or 33 centimetres.
This then is a perfect result. I can (or have already) purchased many $5 glasses and left them where I need them, with the right focal length. +1 for the computer screen, +1.5 for reading, and +3.5 for electronics inspection. If my reading glasses get lost or old, who cares? In fact, after being used to wearing the same pair of glasses for several years, it is quite entertaining to be able to buy new glasses every week, just to have a fresh look!
To anyone who has lived with significant near or farsightedness throughout their life, just hope for the day that you can be diagnosed with the indications of cataract disease, and go with the replacement as soon as you can. There doesn’t seem to be a downside for doing this. But there are substantial upsides to achieve:
- Yes, the shower floor is very grimy.
- And yes, that’s a spider on the bedroom wall over there.
I’m going to be hanging on waiting for my upgrade to HUD, and integration with Alexis or Siri, so that I can finally remember names.