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Thinner flaps, corneal sculpting make LASIK viable in high myopia
Experts agree that new technologies have opened up a greater range of treatment.
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Advances in LASIK technology allow for successful LASIK procedures in higher degrees of myopia, two experts say.
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 Ioannis Pallikaris |
With the ability to create thinner flaps, LASIK is the procedure of choice in –4 D to –10 D cases, Ioannis Pallikaris, MD, PhD, said at the World Ophthalmology Congress in Hong Kong.
Dr. Pallikaris, an innovator of LASIK technologies, said femtosecond laser technology can be combined with surface ablation, using topography- or wavefront-guided treatment, to custom sculpt the corneal tissue. In almost all cases, it is possible to have residual corneal thickness of more than 300 µm, he said, but an ideal thickness of 130 µm is a recent topic of discussion.
Used together, these technologies allow “extremely high patient satisfaction,” Dr. Pallikaris said.
John S. Chang, MD, whose Hong Kong practice has treated approximately 50,000 LASIK cases, agreed that higher myopia cases are treatable with combined LASIK technologies.
“If you don’t see the high myopes, we’d all be out of business in Hong Kong,” Dr. Chang said at the WOC, adding that the average myope in Hong Kong is at –7 D.
Advantages of LASIK
LASIK for high myopes offers many advantages. It is safer than phakic IOLs, outcomes are more predictable than clear lens exchange, there is faster recovery, fine-tuning is easier, and cost is lower, Dr. Chang said. He credited technological advances, such as use of femtosecond laser, with optimizing LASIK in higher myopes.
“With the customized flaps today, we do excimer laser or customized shape and thickness at the edge of the flap. So in this way, we can have thinner flaps and we avoid the post-LASIK corneal ectasia,” Dr. Pallikaris said, noting that the many ways to customize LASIK depend on the patient and the procedure.
Low myopia vs. high myopia
Dr. Chang treated 2,536 high myopes ranging in severity from –8 D to –16.75 D and 2,804 low myopes with LASIK between 2002 and 2006 and presented follow-up data on these cases at the WOC.
In subjective questionnaires from 1,250 respondents, both high myopes and low myopes, Dr. Chang said that fewer high myopes (0.4%) were “very dissatisfied” with their results than low myopes (1%).
Overall, the percentage of highly myopic patients encountering severe symptoms of halo, glare and blurriness were small to minimal, 1% to 3%, similar to the rate found in low myopes. Other disadvantages of LASIK include smaller pupil zones, less stability, less tissue for future surgery and higher risk for ectasia.
“We spend less time with our low myopes telling them about the halo and glare,” Dr. Chang said. “Whereas when we had the higher myopes, we really [tried] to lower their expectations. And that’s probably why the severe symptoms were much less, I believe, in the high myopes.”
“Also in Hong Kong, we’re in mostly an urban environment,” he said. “Night vision is not so much of a problem because most people don’t drive. Therefore, driving at night is not really a serious problem.” In such an environment, LASIK is the viable choice, Dr. Chang said.
In Dr. Chang’s survey, convenience ranked about the same for both groups, but the need for spectacles was greater in the high myopia group, 3.7% compared with 2.2% in the low myopia group.
In either group, no eye lost more than two lines of best corrected visual acuity; one eye in the low myope group lost two lines and three eyes in the high myope group lost two lines. One percent of patients in each group regretted having the surgery.
The take-home message of the discussion between Drs. Chang and Pallikaris regards the safety of LASIK in treating higher myopia cases and how the indications for LASIK may be extended.
– Lucio Buratto, MD
OSN Europe/Asia-Pacific Edition Board Member
For more information:
- John S. Chang, MD, can be reached at Guy Hugh Chan Refractive Surgery Center, 2 Village Road, Happy Valley, Hong Kong, China; 852-2835-8885; fax: 852-2835-8887; e-mail: johnchang@hksh.com.
- Ioannis Pallikaris, MD, PhD, can be reached at the University Hospital of Heraklion, Ophthalmological Clinic, P.O. Box 1352, Voutes, Heraklion, CR-71003 Crete, Greece; 30-81-3923-51; fax: 30-81-39-46-53; e-mail: pallikar@med.uoc.gr.
- Pat Nale is an OSN Staff Writer who covers all aspects of ophthalmology.