EyeWorld Asia-Pacific December 2011 Issue

December 2011 12 EW FEATURE said. These may be patients whose vision has changed over time due to presbyopia. For those in the initial group, Dr. Lindstrom typically waits about 3 months in myopes for eyes to stabilize and a little bit longer for hyperopes. “In hyperopic patients I’ll often encourage them to wait 6 months,” he said. The exception here is the patient who for some unexpected reason is way off, which fortunately Dr. Lindstrom finds is a rare occurrence. “I’ve done a few enhancements even within a week or two of surgery,” Dr. Lindstrom said. “I’ve done this not just on my own patients but sometimes on patients referred in when lasers were programed improperly and they ended up with an outcome that they couldn’t tolerate and they were unable to wear contact lenses or get temporary glasses.” But given his druthers, Dr. Lindstrom would prefer to wait for a stable outcome. “Then we’ll be more likely to hit it dead on with the second procedure and not have to go to a third,” he said. Dr. Durrie agreed that the 3-month visit is optimal for myopic procedures and the 6-month one for hyperopic or PRK retreatments. For the majority of cases he strongly cautioned against extremely early retreatment. “We analyzed our data at one point in time and found that if we used the 1-month visit as a time to analyze whether the patient needed an enhancement or not, 50% of the people we would have done an enhancement on wouldn’t have needed it if we had waited for the 3-month mark,” Dr. Durrie said. “I find that when I quote that to patients, saying that it’s almost a 50/50 chance that if we tried to decide at 1 month whether some- one needs an enhancement we’d be wrong, and tell them we might as well wait, they always wait.” Post-IOL enhancements Likewise, if a patient needs an enhancement after having an IOL implanted, it is important to wait for the eye to stabilize. David A. Goldman, MD, assistant professor of clinical ophthalmology, Bascom Palmer Eye Institute, University of Miami, Fla., USA, finds that many of these IOL patients who need retreatments have undergone previous refractive surgery. “A larger majority of patients that we’re seeing referred in now are those who have had previous LASIK who then have cataract surgery and have refractive surprises because the Ks were so hard to measure,” Dr. Goldman said. If the error is large Dr. Goldman may consider piggybacking a lens or doing an exchange, but frequently will use laser retreatment instead. “Oftentimes there’s astigmatism involved as well, which is corrected with a sulcus intraocular lens and so we’ll move to laser vision correction,” he said. “Typically once they’re a few months out of surgery, and they’ve had a YAG capsulotomy and it looks like their refractive error is stabilized, I’m comfortable offering them laser vision correction to sharpen their vision.” In cases where IOL patients have had previous LASIK Dr. Goldman will typically do PRK retreatment. It’s important in such cases to make it clear that the results will not be instantaneous, he stressed. With a case involving an IOL retreatment, Dr. Lindstrom typically waits to do LASIK or PRK enhancements until the refractive outcome is stable, usually at the 2- or 3-month post-surgery mark. There are exceptions, however. “If you have a big miss, sometimes you find yourself fixing it right away, with an IOL exchange or a piggyback, or with small incision cataract surgery.” He pointed out that practitioners can actually do a LASIK or PRK retreatment quite early these days because of the use of self-sealing IOL wounds. Weighing enhancements options The length of time that has passed since the original LASIK procedure can alter the challenges CHAN Wing Kwong, MD Visiting Consultant, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Eye & Retina Surgeons #13-03 Camden Medical Centre 1 Orchard Boulevard, Singapore 248649 Tel. no. +65 6738-2000 Fax no. +65 6738-2111 wkchan@me.com M y own experience concurs with the article that the enhancement rate after LASIK is about 5% in general. It tends to be less than that for the lower myopes and higher than that for the high myopes purely as a function of the increasing standard deviation of LASIK outcomes as the amount of refractive error treated increases. Whatever the enhancement philosophy of the surgeon, it bears well to remember the adage “Treat the patient, not the refraction”. In other words, refractive surgeons should not just treat patients by the numbers. If the patient is happy seeing 6/12 with a -1.00 D residual refraction, one should leave this alone. Conversely, if the patient is 6/6 unaided and not happy despite an emmetropic refraction, we should look for the source of this dissatisfaction and correct it where possible. I absolutely agree with Drs. Lindstrom and Durrie that enhancements should not be undertaken earlier than 3 months after the initial surgery and it is recommended to have at least two refractions taken 1-2 months apart to ensure a stable refraction. Some high myopes and hyperopes may not have a stable refraction for 6 or more months. Patience, in both the patient and surgeon, is the key to a successful and final enhancement. With regard to the technique of performing a LASIK enhancement, like Dr. Lindstrom, I never recut a flap. I have lifted flaps 10 years after the original LASIK without problems. Flap recuts can result in an irregular stromal bed, whether done with a microkeratome or a femtosecond laser. Unlike Dr. Durrie, I do not see an increased incidence of epithelial ingrowth after flap relifts compared with primary cases. I pay meticulous attention to handling the epithelium at the edge of the keratectomy in a flap relift, taking care not to trap any epithelium under the flap. I also routinely use a bandage contact lens for 24 hours post-enhancement to ensure good flap adhesion to the stromal bed so as to encourage the epithelium to regenerate along the correct plane. These two practice points make my incidence of epithelial ingrowth no different in primary or enhancement LASIK cases. Post-IOL enhancements for residual refractive errors are uncommon. They are most likely in patients with previous corneal refractive surgery like LASIK and PRK. Awareness of the existence of such a post-refractive surgery cataract patient and biometry with laser coherence interferometry coupled with modern IOL formulas such as the Haigis-L will reduce the likelihood and magnitude of such errors. Another favorite formula that I use to increase the accuracy of the IOL power in such patients is the Modified Masket formula. If indicated, I prefer to treat these refractive errors with LASIK rather than surface ablation at 3-6 months post-IOL provided the corneal parameters are suitable for corneal refractive surgery. IOL exchange or a piggyback IOL is a last resort for me as the patient has to undergo another intraocular surgery. In conclusion, surgeons need to remember to treat the patient, and not the refraction. Time is the surgeon’s and patient’s friend and we need to patiently wait for a stable refraction before performing an enhancement. Editors’ note: Dr. Chan declared no financial interests related to his comments. Views from Asia-Pacific continued on page 14 Up - from page 11