One of the biggest decisions facing middle-aged people who are contemplating Lasik, other than whether to do Lasik or not, is whether or not to go for "monovision”. For those unfamiliar with the term, this literally means “seeing with one eye”. What we actually mean by monovision is that each eye is treated differently by the laser so as to make the dominant eye perfect (i.e. plano – no spherical or cylindrical errors – seeing 20/20 or better) for distant vision, but leaving the other eye somewhat nearsighted, say 20/30 to 20/50 or so.

Why do this? Well, as we get old, we find it gets harder to focus on things up close. For people who are nearsighted and wear glasses, this is not so bad. They can simply take their glasses off and read. For those who had good distant vision all along, or for the nearsighted folks who wear contacts, they will now have to start using reading glasses. Lucky them if they are out someplace and they cannot read because they left their glasses at home. For those who were farsighted all along, well, their increasing farsightedness will make up-close activities even more difficult.

(I might add that for nearsighted people with astigmatism, this “taking their glasses off” doesn’t work. I had over –3 diopters of astigmatism in my non-dominant eye and couldn’t focus on anything at all, and barely on things with my other eye, which had –1.5 diopters of astigmatism.)

Nearsighted people who have Lasik and are corrected to 20/20 or better will no longer be nearsighted. When they reach their 40’s, before they know it, they will find they are starting to have trouble reading the fine print in dim light. Over time, they will have trouble reading anything and they will need reading glasses to help out. This is a normal part of the aging process. For me, buying my first pair of -1.00 readers at the flea market is as memorable as, well, we won't go there!

Consider one who is nearsighted and, at age 40 or so, has Lasik and is corrected to 20/20 in both eyes. He will have perfect distance vision but within a year or so, when he goes to read the morning newspaper, he may find he has trouble focusing. What has happened? Presbyopia has caught up with him. Had he not had lasik (and if he didn't have lots of astigmatism), he would find that if he took his glasses off, he would be able to read just fine. But, with Lasik, since he is no longer nearsighted, he can’t focus on things up close as well. So, he finds he now has to get a pair of reading glasses. Will he be happy about this? Probably not, as he has given up his distance glasses, and several thousand dollars, so he can wear reading glasses.

Had he not had Lasik, he may or may not have had to eventually get reading glasses. If he wears contacts, he will, as his contacts correct the nearsightedness, but if he wears glasses, me may find that simply by removing them, he will be able to see for many years to come. You see, as we continue to age, presybopia continues on. After a period of time, however, the eyes will again stabilize, usually after regressing -2.5 to -3 diopters. Thus, as you age, you will start out with -1.00 readers, then over the years, go to -1.50's, then -2.00's, etc. By age 60 to 65, you should reach stabilization.

When Lasik is done on a person in their 40's with myopia, he will be able to see distant things without corrective lenses, which will be thrilling. However, he may be in a state of shock to discover that he now needs readers. He may feel that he wasted his money on Lasik as he is stuck with having to use glasses. I mean, picture this. Everyone at the office knows he just spent $4,400 to have Lasik so he could throw away his glasses. So, they come by afterwards and, gee, what do they see – he is staring at the computer wearing glasses granny glasses. People will make fun of him and he will be a tad upset and frustrated.

One solution that people have used since the early days with glasses and contacts is to go for monovision. Thus, you correct one eye to be plano, so you have good distance vision, but you keep the other eye nearsighted, so you can read. Thus, when you are outside, you use your dominant, distance-corrected eye to see by and, when indoors reading, you use your non-dominant, nearsighted eye.

This sounds a little screwy. With monovision, you can never really see anything totally perfectly – vision in one eye or the other will always be blurry. But, with some time to adjust, many people find it preferable than to keep a pair of reading glasses handy at all times. For example, suppose you go to the grocery store and you want to read the ingredient lists of a can of soup. Without monovision, you would have to pull out a pair of reading glasses (or wear bifocals all the time). With monovision, your brain automatically kicks in the right eye to see with. Likewise, when you go outside, your brain automatically kicks in the dominant eye, and you see great.

So, monovison seems to be a great tool in that you can see both up close and distant objects without needed glasses all the time. When monovision is done on patients in their presybopic years, they will not have the immediate shock of needing reading glasses.

But there are issues to deal with.

In my case, my non-dominant eye seems to be stablizing at around -.5 to -.75 D of myopia (with a comparable amount of astimgatism, but we will neglect that). So, right now, I can read great. Whereas I was in -1.00 readers pre-Lasik, I now need no corrective lenses to read, except the smallest of type. However, as I continue to age, my vision will continue to get worse for up-close things, and the mild amount of monovision I have will cease to be effective. Whenthat happens, I will find that I will have to get readers. Bummer. I will then need to carry around with me reading glasses. So, my left eye will be not only weak for distance, it will be weak for reading, too.

At that time, I will have a few options. As I just mentioned, I can carry around readers. For best results, I would have each eye corrected so I could read equally well from either eye. Second, I could wear a contact lens (or bifocal glasses) in the left eye, increasing the degree of monovision. Third, I could get an enhancement of the left eye to make it more nearsighted, thus increasing the degree of monvovision. Fouth, I can hope that the technology to treat presbopia will be developed and be widely and economically available. That would be great!

But, as that last option is not yet viable (there are studies and things show promise), let's look some more at stronger monovision, which is another issue I have with having monovision done. Notice that when you look through a pair of glasses used to correct for nearsightedness that things seem further away? This is because it takes a negative lens to correct nearsightedness, which is like looking through a pair of binoculars backwards. (Looking through glasses that correct for farsightedness, which reading glasses do, makes things look closer – they magnify, as they are positive lenses.) (Contact lenses do not have this problems – things look the normal distance away. This is why, if you change from contacts to glasses, you trip over things for a while as you get used to seeing things being farther away than what they really are.) Here is the major problem with strong monovision, as I see it. If you have –2D of nearsightedness to correct in one eye, and you use glasses to make the correction, there will be some major problems, as your brain has to reconcile the different images it is seeing. One eye seems things at one distance, while the other sees it as being a bit farther away. You may get used to it, and it may cause headaches, but it will be difficult. (I think that about -2 to -2.5 degrees of difference in the eyes is about all one can tolerate, but this amount, fortunatly, is near the upper limit for correction you will ultimatly need as you age.) Thus, I would think that if you get strong monovision, then you would need to wear contacts when you want to drive at night or when you really need good vision from both eyes. If you have mild monovision, then this is not a problem, but you will need to wear readers sooner.

The main issues with monovision, to summarize, are that while it helps you read, the benefits are temporary unless, perhaps, you have stong monovision, which you may have problems dealing with.

Thus, the only advantage I see with monovision is that it will delay the need for reading glasses for some number of years. But by having monovision, the price you pay for avoiding readers for a while will be that you will have mismatched eyes, and you will need distance glasses in order to attain the best distance vision, which you may need especially at night when driving.

Is monovision really worth it? If we in our 40’s (and older) don’t have monovision, yes we will be quickly thrown into readers, but isn’t that actually normal? The people in the 20’s and 30’s will have to go through this, too, so is it so bad? Is monovision via Lasik something that might only temporarily appease us patients who thought we could throw our glasses and contacts away? Though we may like monovison now, will we like it later when we not only have to go out and buy readers, but we find that we need yet another pair or glasses in order to have the best distance vision?

As I said, I had monovision and I basically like it now, but will I be glad I had it in 10 years? I don’t know. I don't look forward to having to have an enhancement in a few more years to increase my monovision. I hope that there will be a treatment for presybopia that will be feasible so I can treat both of my eyes and see like a 20 year old with 20/20 vision.

At this point (mid Feb, 2000), my left eye has a sufficient amount of residual astigmatism that I could probably get an enhancement to eliminate most of it. It is my understanding that for every 1D decrease in astigmatism, there is a corresponding decrease of .5D in myopia. Thus, if I correct my -.75D of astigmatism, I will lose some .25 D of my myopia, changing my sphere from -.5 to -.25 D of myopia. This would effectively kill off my monovision. I suppose they could then re-correct the myopia to make it worse to give the monovision back (i.e. take the .25D of myopia back to maybe -1D), but I think that would require a technique they use for farsightedness, which I am not sure I would want. So, I may be facing the question of getting rid of the astigmatism and needing readers, or living with the astigmatism and get by without readers for a few years.

I have no idea yet what I will decide. I think I would lean towards getting rid of the astigmatism. Heck, if I had perfect vision all along, I would be needing readers anyway, so why buck nature?

Certainly, as my ramblings have shown, monovision is confusing. I think it is confusing because there are no clear cut, "yes or no" answers to our questions. Plus, monovision is a compromise that we both love and hate at the same time.

As for my advice on whether to have it done or not, I am too confused to give any clear response. It think it is great for a short term solution, but you have to realize that you will continue to age and, unless you get strong monovision, perhaps, your vision will be compromised in that your monovisioned eye will soon be somewhat useless without corrective lenses.

I have been hearing from lots of people on this issue. It is a recurring theme on the bulletin boards and I hope this article has been of some help, though I am afraid it might add even more noise to the subject. But, please, give my your thoughts and inputs on this.

Well, as you can tell if you read the rest of this site, I did go for an enhancement of my left eye. It was not to get rid of the monovision, but to try to eliminate the fuzzy vision I was having inside when looking down long halls on in place like Walmart. An unfortunate result of the enhancement was to overcorrect me by about .5D. This not only got rid of my left eye's nearsightedness (and its great ability to read the fine print for the first time since I was in grade school), it pretty much destroyed my ability to read with it at all without correction. My plano right eye still does a pretty decent job, but not my left eye (which also still has a touch of astigmatism), can only read large print now.

Since the enhancement, I have seen a slow but steady progression of presbyopia. While I still get by with +1.00 to +1.25 readers, I need to dig them out more and more often, and in all but fairly bright light, I need them to read a newspaper. Had I not had the enhancement, I think that my left eye would still be able to pick up the slack and keep me out of readers. I guess I will still have to wait a while longer to see how bad my presbyopia gets to determine at what point, if any, I would have had to get readers had I not had the enhancement.

So, I still have no clear-cut answers on the question of getting monovision. I think I am a little fortunate in that, at age 47, I can still function pretty good without readers, whereas others who are younger than me can't function at all without them. If this means I will not end up needing +3.00's to read, or if I might stabilize at +1.50's, I don't know. If the former, then I will be glad I got the enhancment. If the latter, then I will realize I made an error.

My best advice at this point is to speak with your regular eye doctor about it, think about it, ask others about it, maybe try it out with contacts, then tell your surgeon what you want. I don't think you can make a "wrong" decison either way you go though, again, with monovision, you will always need corrective lenses to get the best vision, whereas without it, you will only need correction to read.