Hollis Lasik

Monovision, a procedure of Perfection

D. Stephen Hollis, MD

I started fitting contact lens for monovision in 1977. Two years later I began to do radial keratotomy and immediately used monovision in patients older than 43. I would do mild monovision from 43 to 46 and full monovision starting at 47. I found from experience that patients 40 to 43 never adapt to monovision. They cannot understand why they want to have blurred distance vision in one eye, when they can see up close with both eyes.

A simple test of dominace is to hand a disposable camera to the patient with their glasses on. They will align the camera with their dominant eye. My method: I have them hold a sheet of prescription paper with a 1 inch hole torn in it. With both hands at arms length, and their glasses on, I have them elevate their hands to eye level (still at arms length) and look a the tip of my index finger held just below my right eye with my left eye closed. I am then looking at the dominant eye.

Typically I correct the dominant eye for distance and the non-dominant for near. But, in pretesting with contact lens, some patients prefer the reverse. I attempted monovision in most of the 20,000 cataract surgeries I performed. Sometimes, the non-dominant eye developed the cataract first and I would correct it for distance. At a later date the patient would develp a cataract in the dominant eye. I corrected the dominant eye for near and found that a few months later, the patient had switched dominance. Dominance is not fixed and iron clad.

I have never seen a man under 42 require a bifocle, but I have seen 1000 ladies need a bifocle prematurely. This has been over my 30 year carreer. The history will usually show they had a partial or complete hysterectomy 7 years before. I have had amazed women ask me “Does it show?” It does show in the eyes. A partial or complete hysterectom, induces an early presbyopia, and the requirement of a stronger than normal add. I have seen a 38 year old lady that needed a +2.50 add at 16 inches. The Berens rod is inaccurate in ladies after hysterectomies. In my experience, it takes 7 years to have this effect post hysterectomy.

Only 1 % of right handed men are left eye dominant. But, over 50 % of right handed ladies are left eye dominant. It will take you one day in your clinic to prove what I just said. I believe eye dominance is more related to which side of the brain we are using than it does being right or left handed. Right handed men that are left eye dominant, often in my experience have “feminine” skills such as cooking, painting, in touch with emotions, musical skills, etc.

If the correction is done perfectly, I find that 99 % of patients adapt to monovision. If at 6 weeks, they show interference (distance vision improves when covering the near eye), I recorrect them for distance at no charge.

I sometimes try soft contacts in the office to give someone the experience of what I want to do. One person said “I am nauseated”. That was a definite indication that they would not adapt. I have tried monovision in patients that had failed with monovision with contacts, espcecially if they have a diopter or more of astigmatism. Toric contacts give a rotation and a constant blur/clear vision, that does not work when one eye is for near the other for distance. Combined together, the patient can tolerate a little blur in one eye at a time. But disassociate the two eyes with monovision and when either eye is blurred the patient loses function. One cannot approximate monovision with toric contact lens. It is not possible. Single vision contact lens may be used if the astigmastism is no more than 0.75 diopters to approximate monovision. The result is seen 20 minutes later by talking to the patient, not over weeks as some have said.

Monovision does not work well when one eye is slightly amblyopic, eg. 20/30. I have tried it and could not get it to work. I do both eyes for distance and they need reading glasses. I have seen legal actions where doctors did not think it was proper to do lasik on amblyopic eyes. If glasses yields little improvement, eg. only 1 or 2 lines of vision improvement, this may make sense. I can see no reason to not do refractive surgery when the vision goes from hand movement to 20/60 or better. I have seen several patientes with refractive amblopia improve 2 lines, a year after full correction of their amblopic eye. This is some of the more exciting work I have done in my career, doing refractive surgery on mildly amblyopic eyes.

Misalignment of the eyes will often worsen if monovision is attempted. If the patient does not have double vision, and the misalignment of the eyes is not noticable, they may tolerate monovision. I inform them I am not sure, so if it does not work, they may require a reversal of the monovision. I will procede if the patient is well informed.

I have attempted monovision 40,000 times in my career. I have had patients come to me for monovision after having lasik done on both eyes before. They had not been offered the option of monovision. I tell my monovision patients they may need driving glasses at night to prevent the glare in the near eye. I tell them that this is the least onerous pair of glasses because they are in your car and you only wear them if you need them. Less than one percent of my patients use that option and seem to tolerate the glare.

I had a lady come in after monovision of -2.25 complaing of distance blur, 2 years ago. I do not know why, but I put a -0.75 contact on her near eye changing it to a prescription of -1.50. It changed her opinion completely. She said “I am no longer blurred in the distance and I can still see up close”. One of the biggest complaints I heard from monovision patients was that “I cannot get my computer screen close enough to me”. I believe that the use of computers has moved the near point of most of the population from 16 to 18 inches. Since I incorporated this change in my practice (the target of -1.50 for near, 18 inches), the complaints from monovision, and the success rate have drastically changed to the good. My endpoint for monovision in my cataract patients was a -1.75, which is close to my new preferred one. I attempted monovision in most of the 20,000 cataract surgeries that I performed.

I find it necessary to correct any error in the distance eye that totals -0.75. eg. Pl-0.75,

-0.75, -0.25-0.50, etc, combined with a complaint that the distance vision is not good enough. This is not spherical equivalent, add the cylinder plus the sphere, if it totals 0.75 and the patient is unhappy with their vision, I will correct it. This same error might have been acceptable if both eyes were corrected for distance. When you just have only one eye for distance, that eye must be better than our normal standards. Monovision is therefore a procedure of perfection.

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