April 28, 2015
Over the past 25 years, there have been many exciting advances in the field of refractive surgery, giving patients visual freedom from glasses and contact lenses. Laser-in-situ-keratomileusis or LASIK, is the most common refractive procedure performed today. However, refractive surgery also encompasses presbyopic vision correction in cataract surgery, with the advent of intraocular lens implants that correct for both distance and near vision.
LASIK has been shown to be a safe and effective procedure to correct nearsightedness, farsightedness and astigmatismin for patients who are good candidates for the procedure. I personally perform a full evaluation of each patient in the clinic so that I can better determine if a patient is a good candidate for the procedure. Reasons for which a patient may not be a good candidate for LASIK usually are due to a glasses prescription that is too high in nearsightedness, farsightedness or astigmatism.
The amount of glasses prescription a patient needs is correlated with the amount of cornea (a clear tissue in front of the eye) which needs to be removed and shaped for the patient to be free of refractive error. If too much tissue is removed from the cornea, then a condition called ectasia can occur, which is an instability of the cornea structure. This can lead to a decrease in vision.
Another situation where a patient may not be a candidate for LASIK is when a patient is predisposed to a condition called keratoconus, which is a bulging of the cornea. Patients who are predisposed to this condition should not have LASIK. This is a good reason for a LASIK surgeon to evaluate each patient personally.
The LASIK procedure involves the making of a LASIK flap, which is a thin sliver of tissue on the cornea. In the past, we employed a mechanized blade that would cut this LASIK flap, but with the advent of the IntraLase TM femtosecond laser, we are able to get more consistent flap thickness as well as use less tissue to make a lasik flap. This means more patients are candidates for lasik surgery, as there is more tissue remaining for the laser treatment. In my clinical opinion, it also provides for a safer, more accurate procedure than a mechanized blade.
Now patients looking for excellent results can have higher confidence in LASIK, because the IntraLase laser adds an extra measure of safety. Complications from a lasik flap complication can lead to a decrease in vision and this sophisticated device provides a micron-level accuracy and a dramatically increased degree of control for the refractive surgeon.
After the LASIK flap is made, the flap is lifted and an excimer laser (which would be the second laser used in all-laser, no-blades LASIK) shapes the cornea (a laser ablation) to correct a patient’s vision. Newer generation excimer lasers such as the Alegretto by Wavelight Inc., which I currently use for the patients in my practice, offer a greater degree of accuracy and a wider laser ablation to decrease night-time glare in patients with large pupils, when compared to older lasers of the past.
Another advancement in LASIK surgery is wavefront technology, which can provide greater contrast sensitivity than the laser ablations formerly used. There are wavefront-guided laser ablations where a wavefront measurement of a patient’s eye is used to guide a laser ablation. There is also a wavefront-optimized laser ablation that delivers more energy to the peripheral cornea during an ablation to provide for a more consistently tapered edge of the laser ablation. Wavefront technology is used to increase contrast sensitivity after LASIK, yet it is generally accepted among refractive surgeons that it doesn’t provide for an improved visual acuity. Still, wavefront technology is an important advancement in LASIK surgery.
More than half the people over age 55 have lens opacities called cataracts and more than 70 percent of those over age 75 have this condition. Cataracts can impair vision and treatment is necessary to allow for good functional vision. While natural aging is the most frequent cause of cataracts, others include injury, chronic eye inflammation, steroid use and diabetes.
In the majority of cases, surgery can successfully remove cataracts and restore vision for patients who have developed these clouded lenses that obstruct vision. Today, we remove the cataracts by using ultrasound technology that literally breaks the opacified lens into small pieces, which we then suction out with a surgical vacuum through a 3mm ocular incision. Once the cataract is removed, an intraocular lens implant (IOL) is inserted into the eye folded, and then unfolds in the area of the now removed natural lens. These implants are usually made of silicon or acrylic material that is clear.
What’s really exciting is that we can now offer a new IOL technology which can correct presbyopia, which occurs around the age of 45 in most people. Presbyopia is when a person’s lens is no longer able to focus on near objects due to the aging process. In the past, we only had a monofocal IOL that would allow cataract surgery patients to see clearly without glasses either near or at a distance, but not both.
A new generation of intraocular lens implants has provided greater independence from glasses or contacts in cataract patients. Most work by using technology to create different areas of distance and near focusing in an IOL, thus they are multifocal lenses. Another type of IOL that is used in cataract surgery for presbyopic correction makes use of accommodative ability and attempts to work in a way similar to the natural lens. This IOL however, has had mixed results.
Currently, I use the Restor lens by Alcon, a multifocal IOL, for presbyopic correction in cataract patients, as well as patients who wish to have a refractive lens exchange (non-cataract patients). Candidates for the Restor lens are chosen carefully, as this lens tends to work best in patients who have low astigmatism. Also patients who do a lot of night driving are informed of the possible increased glare symptoms that are associated with multifocal lenses.
If you’re considering having eye surgery for laser vision correction or cataracts, I suggest that you do your research. Find out everything you can about the procedure you are considering and about the surgeon who will perform the procedure. Generally, it is sound to work with a surgeon who has done at least 1,000 procedures in refractive and cataract surgery. It is also good for an ophthalmic surgeon to have had formalized training in corneal and refractive surgery and is certified by the American Board of Ophthalmology. Having published in peer-reviewed journals can also give an idea of a surgeon’s efforts to contribute to the field of ophthalmology, and more specifically, to refractive surgery.
I am optimistic that even greater advances in the field of surgical vision correction are ahead. Currently, researchers are studying alternative, more advanced solutions to the problem of presbyopia, the loss of focus for up-close reading vision that occurs around the age of 45.
While there are presently some functional solutions for presbyopia in patients who have cataract and clear lens replacement surgery, these lenses require further advancement and refinement, in my opinion, for excellent results in a more widespread patient population.
There has been an evolution of surgical vision correction over the past two decades and never before have patients been afforded such high levels of safety and excellent outcomes. Laser vision correction is a safe and effective procedure to free people, who are good candidates, from glasses and contact lenses. Presbyopia correction will continue to advance to where patients will no longer need to lament about the loss of seeing clearly to read at the age of 45 and older. We will have greater options to correct these vision problems, to allow us to live and perform in our daily lives.
David M. Choi, M.D., is a Board-Certified Ophthalmologist with Riverside Medical Clinic who sees patients in two RMC locations, Riverside and Canyon Springs/Moreno Valley. Dr. Choi earned his medical degree from the University of Illinois, Chicago and completed his residency at the University of Florida. He also completed a Fellowship with Corneal Consultants of Indiana. He has published in peer-reviewed ophthalmology journals and serves as clinical staff in the Department of Ophthalmology at Loma Linda University. He joined Riverside Medical Clinic in 2002. You can reach him for a consultation at (951) 321-6356.
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