Standard vs. HD procedure

Learn about terminology behind our procedures


Patients are often confused about all the terminology regarding LASIK and LASEK. Basically, the former is cutting, and the latter is non-cutting. A totally different issue is custom vs. standard. For clarity, here are all the terms that all indicate custom, meaning these terms are all synonyms: custom, wavefront, CustomVue, Hi-Def. The non-custom, non-standard type of treatment is usually referred to as “standard” (because non-custom or non-hi-def sounds bad to the customer). You should be very clear about what is the difference between these two options.

So what’s the difference?

standard procedure
Standard means the laser is correcting your prescription to the same degree of precision as glasses or contacts–namely, in increments of +/- 0.25 diopters. For example, your contact or eyeglass prescription is always given in quarter diopter increments, like -3.00 or -3.25, there is nothing in-between. If you’re observant and have looked at your prescription over the years, you’ve already noticed this, so if your optometrist gives you a prescription for new glasses that were -3.18, you would say something like, “Wow, I guess you guys have figured out how to grind glasses more precisely these days–that’s really cool!”

Unfortunately, that’s also not true. It’s basically impossible to make eyeglasses or contacts that accurate. More unfortunately, these days some contact and lens manufacturers are trying to market their products as “digital” or “custom” or “wavefront.” This is impossible, as when you look out of contacts or glasses, the contacts move in your eye, and your eye looks out of different parts of your glasses.  Therefore, even if the lens is “custom” you will wind up looking out of the wrong part of the lens, so you will not see any benefit from your “digital” lenses (that you paid more for).

In contrast, with LASEK, you can get a correction that is actually the precise one you need–not some average to the nearest quarter. Moreover, with the VISX S4 IR system, you will actually have 50 different prescriptions lasered onto your cornea accurate to the nearest hundredth!  This is why these days, after our Hi-Def SafeSight procedure, the majority of our patients are actually seeing better without glasses and contacts than they did with them–because it’s just a much more accurate prescription.

Furthermore, when Dr. Chynn was performing CustomVue LASIK, he wasn’t getting nearly this many people better than 20/20. The reason is that the CustomVue WaveScan is obtained before the cut in LASIK is made—yet many published studies have reported that cutting a flap distorts the WaveScan. Therefore, the surgeon winds up using a WaveScan to laser the cornea that is not 100% accurate–because it was obtained before the flap was made.

This is why when Dr. Chynn was performing CustomVue LASIK, he was only getting about 10-20% of his patients seeing better than 20/20.  Once he switched to LASEK, he immediately started getting 30-40% of his patients better than 20/20.  Now, it’s more like 50-60%. The reason his results are better now, with the same laser, is because by not cutting a flap, the WaveFront scan is 100% accurate, and not distorted by the flap, so the treatment is exactly what is needed, rather than what would have been needed if a flap hadn’t been cut (but was) in LASIK.

We understand that this explanation is somewhat complicated, so invite you to call our center, make an appointment for a free consultation, and then have Dr. Chynn or one of his 4 doctors (all true MD surgeons, not ODs or optometrists or “techs”) explain this in more detail.

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