In my last blog concerning the right time for LASIK, I wrote about some of the advances in the technology of the procedure itself. Today I want to focus on the advances in the evaluation of a patient and determining whether he/she is a good candidate for laser vision correction (whether it be LASIK, PRK, LASEK, or epiLASIK). Patients especially in New York, New Jersey, and Connecticut seem to be very unsure what makes a person a bad candidate for LASIK or PRK. Most think that if they have astigmatism they aren’t good candidates. That’s not true, even large amounts of astigmatism can be treated now.

One of the great advances in the evaluation of a patient came with the invention of the High Resolution Pentacam – a diagnostic machine which provides a beautiful and complete picture of the entire front of the eye. Before this we were limited to corneal topography which only shows us the front surface of the cornea. This is good in detecting some corneal diseases but usually not until these diseases have progressed to often an advanced state. The goal has always been to detect the early stages of these conditions so LASIK can be avoided or PRK or other surface treatment substituted if indicated.

An early attempt in going beyond the anterior surface of the cornea was the introduction of the Orbscan. But this machine suffers from a variety of inadequacies and doesn’t give a true and reliable picture of the posterior surface of the cornea. The visualization and analysis of the posterior surface of the cornea is critical in determining whether a patient is a good candidate for LASIK or PRK/LASEK – for many corneal diseases start by altering the back of the cornea.

With the introduction of the Pentacam and now the High Resolution Pentacam, a true picture of the cornea, anterior and posterior surfaces, is obtained. The analysis of this data is also at a high level making the assessment of the corneal health and structure easy and reliable. This translates into a better and more accurate determination of the patient’s candidacy for laser vision correction. Subtle characteristics of the cornea which can affect the results of the procedure can now be seen. The planning of the surgery can be finessed and the visual results improved.

Also, our knowledge of how systemic disease can affect laser vision correction has advanced over the past 10 to 15 years. We now know which medical conditions would prevent a patient from getting good results, which conditions we used to think would provide bad results but now have no effect on the results, and other conditions which should be treated first and then LASIK performed. It is very important to discuss any medical condition you might have with the surgeon during your lasik consultation.

For most of us in the tri-state region and especially New York, PRK or LASEK or epi-Lasik seem to be less-than ideal vision correction procedures simply because the healing time is longer than with LASIK. Most people want to enjoy the benefits of laser vision correction as quickly as possible and return to their regular routine promptly, so if they are candidates for LASIK that is what they choose. However for many reasons surface ablation techniques like PRK, LASEK, and epi-Lasik may be preferable. When we talk about any of these three procedures we are really talking about essentially the same thing with very minor differences in the actual surgical technique giving rise to the different names. For the consumer, they may be considered one in the same – a procedure in which no true corneal flap is made and so the laser pulses are applied to the ‘surface’. (In LASIK a corneal flap is made and the pulses are applied to the ‘middle’ of the cornea and then the flap is repositioned.)

After the PRK, LASEK, or epi-Lasik procedures, the surface epithelium (skin) of the cornea has to grow back and so the first few days can be uncomfortable and the vision variable. (In LASIK, this layer is preserved.) As healing continues the vision generally improves over the first few weeks and months. Usually by the third to fifth day the vision is good enough, and the patient comfortable enough, to return to work, school, or other normal activities. (It is sometimes hard to convince New York, New Jersey and Connecticut workers to take a few days off.…) Advanced surface ablation techniques like these are used for people with thinner corneas, in some situations where the corneal shape is less than ideal, or where the patient prefers not to have a corneal flap. These techniques leave a thicker base to the cornea after laser correction since the treatment starts at the surface. This is important in thin corneas.

PRK/LASEK/epi-Lasik are not always indicated in people with large prescriptions because there is an increase in the possibility of corneal haze formation, which can cause a decrease in vision and increased side effects like glare and halo. With the use of mitomycin C , along with the newer scanning spot lasers, their incidence is decreased.

LASEK and epi-Lasik were developed in the hope of avoiding the major drawbacks of PRK: the discomfort and long healing time. This proved not to be the case. However, because the corneal base is left thicker and there is no flap made, PRK/LASEK/epi-Lasik may be safer. However, in experienced hands, the risk of flap complications in LASIK with the newer microkeratomes (flap makers) is minimal. Fortunately, the final visual results with PRK, LASEK, epi-Lasik and LASIK are equivalent and the major disadvantages of the surface ablation techniques can be minimized.

The past 25 years or so has seen the advancement in technology, techniques, and knowledge about laser vision correction that allows consistently great visual results, few if any side effects, and unprecedented safety. Whether an individual decides to have LASIK, PRK, LASEK, epiLASIK or any similar Advanced Surface Ablation or Laser vision correction, the results should be excellent. For the average person there is nothing new on the horizon that should make a person wait to have laser correction of their vision. I will discuss just a few of the advances in the last few years that have made a significant difference.

The advent of newer and safer flap-making devices (microkeratomes) has eliminated many of the potential risks to LASIK surgery, especially if used by an experienced surgeon. With the addition of laser microkeratomes (Intralase and Ziemer) the ability to make thin, accurate, smooth, and large flaps (the first step in the LASIK procedure) with minimal chance of complications has improved overall results.

With advanced surface treatments (LASEK, EpiLasik, PRK) the risk of haze formation and subsequent visual complaints has been decreased with the use of the application of a mitomycin C solution for a few seconds after the laser treatment. And it appears with the newer scanning spot lasers with their smoother treatments, the healing time for surface procedures is decreased, giving a quicker recovery – this is in addition to their creating less visual side effects.

I think the greatest advance has been in the laser that does the reshaping of the cornea and the correction of the vision. We are now at a point where excellent visual results should be commonplace. The Allegretto laser developed over ten years ago in Germany and the first laser to do a Custom laser treatment has set the bar for all other lasers to try and match in terms of visual results. No other laser maintains the natural shape of the cornea (the normal curvature of the front of the eye). Every other laser will distort the shape – in nearsighted patients, the lasers flatten the center of the cornea. By maintaining the normal shape, the Allegretto actually improves the quality of the vision after laser correction and instead of creating glare and halos like all the other lasers, can even improve them if the patient has glare and halos to start. Most patients feel their vision is better after Lasik with the Allegretto than it was before with their glasses or contact lenses. The routine improvement in the quality of the vision after laser correction has been the standard result for which refractive surgeons have always strived – and is now attainable.