Farewell to glasses
For about 6 months I have been cognizant that my vision has deteriorated. I also am aware that the deterioration is concentrated in my left eye. I have run through my ritual often: close my left eye and not much changes. Then close my right eye and everything is blurry, multiple images water colored on top of each other. With my glasses off, I can’t see far at all which is totally normal since I am nearsighted aka myopic. But I also can’t see near with my left eye and that is decidedly not normal.
Eye length and refractive error
I know a little about vision and I know that most refractive error is due to eye length. People whose eyes are too long are myopic and those with short eyes are hyperopic. Myopia is an incredibly common condition, particularly in genetically vulnerable populations. In some east Asian communities, a majority of children are myopic. It used to be thought that the was due to too much near vision – e.g. reading – but now it appears that exposure to the full spectrum of sunlight is a big factor and possibly the predominant environmental factor that places children at risk for myopia. [Whatever the case, the take-home message remains to send those kids outside to play, for ever so many reasons!]
Changes in refractive error in adults
Since eye length is the main predictor of refractive error and since adult eyes are not still growing, I wondered how the vision of myopic adults can continue to get more nearsighted. I asked an optometrist this once and he told me, “cataracts.” So I was forewarned. I was particularly forewarned since I have known for a couple of years that I had a centrally “blooming” (an incongruous word for the context) cataract in my left eye. [I am young to have a cataract due to age and sun exposure. It is likely that my cataract developed because of high dose prednisone that I took to treat a particularly bad case of poison ivy. I will spare you the pictures of my bubbling reptilian skin.]
So when I went to see my ophthalmologist, I was both expecting and hoping that my problems with vision were due to my cataract. To start with I saw the technician who did a standard eye exam. It was quickly apparent that I was failing way more than ever before. Not only was I failing while wearing my glasses but I was also not being helped by the offered lenses. he placed lens “one” or lens “two” in front of my eye repeatedly; nothing made the slightest bit of difference. My vision remained blurred and useless. Letters were just guesses.
That the cause of my blurred left eye vision was my “blooming” cataract was quickly confirmed. I also found out that I have a smaller but similarly centrally located cataract in my right eye. So cataract surgery. First the left and then the right.
My pupils were dilated and the cataract was fully visualized. With my pupils dilated, I also had an OCT, an optical coherence tomography scan, which is a way to visualize the retina, including the cell layers. The OCT scan will show any retinal problems such as macular degeneration which might be another cause of impaired vision. It is important to identify any issues that may impair vision after surgery so the patient – in this case, me – knows what to realistically expect after lens replacement.
Every time my pupils are dilated, I am reminded again of how important pupillary constriction is to near vision. Remember that near vision depends on the near triad which is entirely supported by the third cranial nerve aka the oculomotor nerve. The near triad includes 1) convergence of the eyes (both eyes look toward the nose, “cross-eyed”); 2) lens accommodation (the lens “rounds up” thereby increasing the refractive power of the eye); and 3) pupillary constriction. The advantage of pupillary constriction is that the cone of blur is greatly narrowed. Light has to travel straight down the chute so to speak to enter a small pupil. With a dilated pupil, every Abe, Ike, Jake, and Sam (my mom’s version of Tom, Dick and Harry) photon can get into the eye and that is reflected in very poor acuity near vision.
Contact lenses reappear in my life
I was thrilled. There was a clear answer. Surgery. Get the cataracts removed. BUT… what I did not realize was that it was not so simple. My ophthalmologist explained to me that I would need to wear contact lenses.
Taken aback, I asked, “Why can’t I just put a clear lens in the left eye of my glasses?”
“Because of your high refractive error, objects will look to be different sizes in the two eyes.” Aha, I see. I would not be able to merge images. Imagine looking at an object with a magnifying glass over one eye and both eyes open. Nope. Not going to work.
Well, this was a hiccup. At least for the three weeks between getting my left eye and then right eye done, I would need to wear contacts. Not my favorite thing in the world but okay, doable. I wore contacts for probably 20 years. Eventually lost all vestiges of vanity and went for complete convenience. Been happy with that choice for decades.
My ophthalmologist was not done with her surprises. When a cataract is removed, an artificial intraocular lens is put in place of my own opaque lens. She explained that there are two choices which we quickly narrowed down to two:
- Monocular correction. In this approach, one eye is corrected for near version and one for far vision. This is very commonly chosen. Presbyopia, you may remember is “old man vision” in Latin, refers to a stiffening of the lens that starts at birth and starts to interfere significantly with near vision starting at about 40 years of age. Presbyopia is a law that is up there with death and taxes; there is no escape. The effect of presbyopia is that lens accommodation takes longer and longer to occur until a point where there simply is no significant lens rounding. The effect of this is a loss of the ability to switch from far to near vision. Since most cataracts are found in older people, most have presbyopia and since myopia is so common, the intersection – a person who needs correction for both near and far vision – is incredibly common. And this is the category I fall into.
- Correct to a computer focal length. Both eyes are corrected to a diopter of -1. Since I am starting at a refractive error of >8, going to -1 (about 20/40 vision meaning I would be able to see at 20 feet what someone with normal vision could see at 40 feet) is a big change.
Before going into the advantages and disadvantages of these two choices, you may ask yourself why I would not simply correct to perfect far vision, in other words to 20/20 vision. The answer lies more in behavior than in optics. I have worn glasses since I was in the third grade and in all that time, I have been able to see up close really well. As my presbyopia developed, I got into the habit of looking over my glasses to look at near objects. [Comically I continue to look up once I had the contact lenses in…. Both funny and telling as to the power of behavioral habit.] If I were corrected to 20/20 I would not be able to see close at all, at all. I would not be able to read a map, work at a computer, or pick berries without reading glasses. And my far vision would still not be perfect since I have an astigmatism that is not corrected by the intraocular lens.
To decide between the two choices above, I received two sets of contact lenses which would approximate the two options. First I wore the monocular correction set. I adapted to the two lenses by relatively suppressing my right eye for near vision and then suppressing my left eye for far vision. It did not take too long to adapt, maybe an hour or two. But I was very aware that my vision was not great. One big problem with evaluating this approach is that my left eye had a contact lens corrected for near vision. Since near vision involves a constricted pupil, light is forced to traverse the cataract (see Figure below). So vision is compromised no matter what. In far vision, the pupil can be dilated (as long as ambient light is not too bright) and light could find a path to the retina that does not involve the cataract.
When I took off the monocular contact lens set, there were several minutes of disorientation, a feeling of being at optical sea. Everything looked floaty and weird and I did not feel grounded.
The next morning I put in the binocular contact lens set. This set felt instantly right. I needed absolutely no adjustment time. Were they perfect? No. But as far as distance vision, they looked really good. For near vision, there was definitely a blur factor. But I could see the computer and I could read my phone at near arm’s length. I think I would even prefer to forgo a bit more distance vision to get a tad more near vision.
Sayonara glasses! Adieu mes lunettes!
The whole time that I was wearing contact lenses, I felt facially naked. It is a weird feeling to be without my glasses. And not an entirely positive one. In fact, it is more unpleasant than pleasant.
After testing both options, I took out the contact lenses and put on my glasses again. I have worn my glasses ever since. As of tomorrow night, all of my glasses – and I have many pairs (bifocals, sun, reading, computer, and many previous prescriptions) will be useless to me. I gazed at them with some fondness and regret. This is a huge change and not entirely joyous. It is a little scary, a little uncomfortable.
Will I buy new glasses for far vision? Glasses that correct that last bit of refractive error and also my astigmatism. Do I care more about perfect far acuity or about convenience? Will I get bifocals to optimally correct both my near and far vision? Or will I finally just get inexpensive sunglasses and reading glasses as so many people with normal vision do? I lean toward the drug store glasses choice but I really don’t know what I will do. Having the option of not wearing glasses is a strange reality for me.
And then there are truly difficult choices
I went back and forth over the choice of which lens to put in my eye. I am confident about this surgery but it is a one-go chance and there are no re-dos. Whatever choice I make is what I will live with for the rest of my life. Should I go for the convenience that monocular vision provides? In this case, I would not need any correction for anything. Or should I go for far vision correction since I am truthfully more comfortable with glasses than without? I have pretty much decided to do the latter (I still have a few more hours to change my mind).
My decision matters to me but I will be fine either way. I will adapt. Yet, this whole experience made me think about people who have to make truly momentous decisions about their health care. Take the 32 year-old woman described by Henry Marsh in his book, Do No Harm: Stories of Life, Death, and Brain Surgery (Picador, NY, 2014). She had an aneurysm in one of the main cerebral arteries of the brain (the middle cerebral artery). Aneurysms are outpouchings of blood vessels where the vessel wall thins. The bigger the aneurysm, the thinner the wall and the thinner the wall, the more likely it is to burst. The woman described by Dr Marsh had an aneurysm that was 7 mm in diameter. Available information suggested that this was relatively small and had only a 0.5% chance of rupturing each year. However if it did rupture, there was a good chance she would die immediately (15%), within the next few weeks (30%) or in the years thereafter (4% compounding each year).
Compounding the decision was the fact that the location of the aneurysm precluded the simple operation – an endovascular coil that is threaded up into the affected artery from the groin. This is essentially a vascular procedure. For this patient, no coiling would be possible. The only treatment would be a full neurosurgical procedure in which the cranium would be invaded to allow the neurosurgeon to place a clip on the outside of the base of the aneurysm. The opening of the balloon had to be closed off. The procedure to clip an aneurysm carries a risk of stroke that is non-trivial: 4-5%.
At the time that the aneurysm was discovered, it was causing no problems. So here is a healthy young woman without symptoms facing a momentous choice. She could decide to have the doctors continue to monitor the aneurysm with regular scans to check size OR she could have neurosurgery to clip the aneurysm. That is a difficult choice. The woman asked Dr Marsh what he would do. He answered that he would not get it clipped, adding that he “would find it quite hard to forget about it.” She responded, “I want the op. I don’t want to live with this thing in my head.”
Now that is a hard decision. And an important one.