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Should you have LASIK or LASEK on both eyes on the same day?

The norm in the USA and in much of Europe is to do LASIK on both eyes at the same sitting. i.e. treating both eyes whilst the patient is still on the operating table. There is obviously a lot of financial sense in this for the various clinics as it increases their throughput of eyes treated and hence their profits. However, what is best for the individual patient? The arguments are in 2 groups:

1. Safety:

    It goes without saying that if, in a planned bilateral operation, there is any intraoperative complication in the first eye then the second should be abandoned. In practice this usually means any flap problems. I would also include any marked epithelial loss or "slide" due to the passage of the microkeratome. This is because the incidence of the "sands of the Sahara" syndrome is 10 times higher in these cases and will not present until day 1 after the surgery if it occurs. Such epithelial problems are commoner in older patients.

    Any infection, inflammation, flap wrinkles etc. almost always show up on day 1 post op and by waiting 2-7 days between eyes one should avoid a simultaneous bilateral problem. However, these are unusual and most people opt for same day bilateral surgery. I had no bilateral LASIK complications last year.

The only real complication of surface laser, whether PRK or LASEK, is a delayed one of "haze", which is usually maximal about 6 to 8 weeks post-op. Haze is commoner in higher prescriptions or in people with delayed epithelial healing.  We used to do no bilateral PRK's for this reason, but now, as haze is much more uncommon, most people think that up to about -5 Dioptres on the same day is reasonable. I have personally not had a haze problem for the last 2 years, so feel more comfortable going even somewhat higher than -5 in some patients.

    LASIK/PRK is dependant on the technology of the excimer laser machine. These are gas lasers and are calibrated at the beginning of each day and several times during it. They are complicated machines but are generally reliable and have a lot of safety features. However, if there is a technical problem and both eyes are treated, it could affect both eyes adversely without the surgeon being aware of it at the time of surgery. The most likely fault could be a simple over or under treatment which could be corrected fairly easily in most cases. A worse case would be a beam irregularity. There are checks on all the common machines to pick this up but there has been a reported case in Canada of a mirror problem in a machine leading to irregular astigmatism in a group of bilateral patients. These patients were sorted out with a lot of angst and it was realised that the fault in the machine should have been picked up before the surgery. However, it is a salutary lesson!

 

2. Accuracy:

    The bigger the treatment, the bigger the spread of results as noted before. If you fall within the normal spread of results, then doing both eyes at the same sitting will not give any significant increase in accuracy than doing them apart. and this will be the normal experience of most patients. However, if you behave oddly, being at the extremes of the statistical spread, then doing the eyes separately allows the surgeon to alter the laser settings for the 2nd eye. Scientific papers disagree as to whether this really makes any difference, but the latest ones seem to indicate about a 20% improvement of accuracy. Hence on a -7 Dioptre correction with a standard deviation of 0.93 Dioptres, this would lead to a mean improvement of accuracy of about 0.2 Dioptres, which is a small amount.

 

 

3. Subjective:

Sometimes, especially in very high myopes, full recovery of vision can take up to 2 weeks. Thus if you have both eyes lasered on the same day, you may struggle to cope for this time. Similarly, you may find that the quality of vision after Lasik in one eye is not to your liking. e.g. You may have night vision problems  and not want to go ahead with the 2nd for this reason. For these and similar reasons you may prefer to do one eye at a time. (I operate weekly and usually do such patients 1 week apart).

 

In Summary:

   Doing LASIK or LASEK on both eyes on the same day is more convenient, but is a slightly greater risk then doing them on separate days. It is up to each patient to decide what they want to do, after consultation with their individual surgeon. In practice I seem to do well over 90% of patients with bilateral same day surgery.

Note: It is the same risk to do both eyes 2 minutes apart as to do them several hours apart on the same day.