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Consider wide range of options before recommending refractive procedure
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When evaluating the best refractive surgical procedures for their patients, optometrists should be aware of all the options available and the relative benefits of each. It is especially important for doctors to educate themselves on investigational procedures, such as phakic IOLs, the Intrastromal Corneal Ring Segments (ICRS, KeraVision) and laser thermal keratoplasty (LTK), said Cindy J. Baker, OD. Dr. Baker is the comanagement director at the Laser Institute of the Rockies in Englewood, Colo., who lectured on this topic at the annual meeting of the Optometric Refractive Surgery Society in Akron, Ohio.
Getting started
To present a patient’s best surgical options, the comanaging optometrist should research the accuracy of different procedures for different ranges of refractive error, Dr. Baker said. Other important considerations are the immediate and long-term risks and recovery time, as well as the benefits of each procedure for specific refractive errors. Optometrists also should discuss the recovery time for each procedure and the visual requirements for the patient’s occupation.
"One of the most important things is counseling patients ahead of time so they come in understanding the procedure and the reasonable outcomes," Dr. Baker said.
Patients also should understand that in almost every refractive surgery case there will be a trade-off in their postoperative visual acuity, said Stanley B. Teplick, MD, of the Teplick Laser Surgery Center in Beaverton, Ore.
"Let patients understand that their vision may not be as crisp and clear as it is pre-surgery with contact lenses," he said. "If they’re willing to trade off a little bit of crispness for the convenience and the ability to be independent, then they are going to be thrilled. If they continue to compare their results to their preoperative vision, particularly with rigid gas-permeable contact lenses, they are almost universally going to be disappointed."
Another potentially troublesome candidate is the presbyopic patient, Dr. Baker said. "Presbyopes require careful counseling regarding their refractive surgery options. Monovision generally works well for patients who are successful monovision contact lens patients. If a full distance correction is requested, patients should be carefully educated about the need for near correction after the procedure. Despite careful counseling, patients may still come in and say, ‘My near vision is horrible. Nobody told me about this,’" she said.
To protect the comanaging optometrist in these situations, Dr. Baker suggests developing a consent form, even if the surgery center has its own.
Optometrists also should remember that not every patient will be a candidate for surgery. "Be prepared to say ‘no.’ If patients’ expectations are out of line or we do not expect them to do as well as we’d like, we counsel them against refractive surgery," she said.
Presenting options
Advances and developments with laser in situ keratomileusis (LASIK) have made this Dr. Teplick’s procedure of choice for almost any degree of refractive error. While in the past the amount of myopia was the determining factor in selecting a refractive procedure in nearly all surgical cases, comanaging optometrists should consider the skill and experience of their surgical partner in discussing options with patients.
"Two years ago, I would have given you a nomogram: 0 to –2 D, radial keratotomy (RK); –2 to –6 D, photorefractive keratectomy (PRK); above –6 D, LASIK; above –12 D, lens extraction," Dr. Teplick said. "Now everything has changed because LASIK has become the operation that gets the kind of results that patients want, and gets them as quickly as patients want them."
Dr. Teplick performs LASIK on nearly all patients with 1 D to 14 D of myopia who have 4 D or less of astigmatism and on patients with up to 6 D of hyperopia. Despite his preference for LASIK, Dr. Teplick does explain RK, PRK, IOLs and ICRS as other options for the patient.
"Patients should know about all of these, but I think today’s patients are very sophisticated, and very rarely have they not done an enormous amount of research before they go to the doctor’s office," he said. "They know they are here to get LASIK, so I am not going to confuse them by overwhelming them with lots of technical information about their options. We tried that, and it is not constructive."
Treating myopia
The wide array of surgical options allows optometrists to investigate both conservative and aggressive approaches to refractive correction, said Louis J. Catania, OD, president of the Omega Institute, the educational affiliate of Omega Health Systems Inc., in Atlantic Beach, Fla.
In the low levels of myopia, from –1 D to –3 D, very few doctors still prefer RK because it is an inexpensive procedure with documented success, but Dr. Catania considers this a more aggressive approach. Conservative options with which optometrists may be more comfortable that achieve good results are PRK and LASIK.
Another possible correction for low myopia is the insertion of ICRS, which are still investigational. The Food and Drug Administration (FDA) will review the premarket approval application for ICRS, or the KeraVision Ring, this month.
"Conservatively, for patients with 1 to 4 D of myopia, the results [with ICRS] are excellent. Above 4 D, it becomes a more aggressive treatment," Dr. Catania said.
This option will most likely be used in patients with low amounts of myopia who previously would have been candidates for RK, Dr. Teplick said. It offers a relatively inexpensive, potentially reversible procedure, but the drawbacks are that its efficacy still has not been proven and it does not treat astigmatism, he said.
For –4 D to –10 D, LASIK is the current preferable method, but the recent FDA approval of a scanning PRK laser by Autonomous Technology (Orlando, Fla.) increases surgical options, Dr. Catania said.
"Scanning PRK has been shown by all the studies and the data to be pretty good from –4 D to –10 D. I’m not necessarily saying that we should go back to PRK, but with scanning PRK, you have an option again," he said.
In patients with more than 10 D of myopia and more than 5 or 6 D of hyperopia who have early lenticular changes, the best solution may be a clear lens extraction with a posterior chamber lens implant or a multifocal lens implant, Dr. Teplick said.
Clear lens extraction also is a consideration for patients with more than –12 D to –14 D of presbyopia, where accommodation is not a consideration and there has been success with multifocal IOLs, Dr. Catania said.
Patients with 15 D or more of myopia who undergo LASIK tend to have more problems with distorted vision, night problems and loss of clarity, making phakic IOLs a potentially attractive option, Dr. Baker said.
Exceptions, contraindications
Although he has been dissatisfied with long-term fluctuation, haze and discomfort associated with PRK, Dr. Teplick said in rare circumstances it might be a better procedure than LASIK.
"Patients who have co-existing recurrent erosion syndromes, corneal dystrophies and myopia will benefit by going through the basement membrane with the PRK procedure to kill two birds with one stone," Dr. Teplick said.
Both laser procedures achieve good results for most patients with low levels of myopia, but optometrists should watch for certain signs, Dr. Catania said.
"In the lower ranges, the only patients who are contraindicated for PRK are the keloid formers or collagen vascular patients. These are frank contraindications for PRK, whereas with LASIK they are not contraindications," Dr. Catania said.
Contact lens-induced permanent corneal warpage also makes a patient better suited to LASIK than PRK, Dr. Catania said.
"With PRK, you tend to create the same variations in the distortion after the ablation that you had prior to surgery, whereas you get a little more forgiving results with the flap," he said.
Another consideration is a patient’s response to steroids. Patients who have a history of steroid responses fair better with LASIK, because steroids can almost be eliminated in LASIK follow-up, whereas they are essential in PRK post-surgical care, Dr. Catania said.
For the most part, LASIK has fewer contraindications, though there are other cautionary signs of which optometrists should be wary, Dr. Catania said. These include significant peripheral retinal pathology — because of the suction ring used — and corneas flatter than 41 D. A free cap is also a concern, though this is of greater annoyance to the surgeon than the patient. Patients with high degrees of myopia may be better suited to phakic IOLs.
"The combination of a high power prescription and a very flat cornea would mean that you would have to flatten the cornea substantially, going perhaps below 35 D," Dr. Catania said. "There is an increasing amount of evidence that says if you flatten the cornea lower than 34 or 35 D, you are actually producing a poor refractive quality on the corneal surface."
Patients with uncontrolled glaucoma, herpetic diseases or endothelial dystrophies are poor candidates for either PRK or LASIK, he added.
"The endothelium is not adversely affected by any refractive surgeries; however, you need a healthy endothelium to have the quality of the corneal stroma — properly hydrated — to get the optimal results with ablation," Dr. Catania said.
Hyperopia
Optometrists should make patients aware that, in general, hyperopic patients are slower to return to best-corrected visual acuity than myopic patients, and they should expect longer recovery times, Dr. Baker said. The optical zone of hyperopic patients also tends to be smaller, which could cause night glare problems.
Patients with up to 4 D of hyperopia have shown fairly predictable and reliable results following both LASIK and PRK, Dr. Baker said. Research indicates that in PRK there is greater epithelial hyperplasia, which may result in more regression. In trials, LTK has shown promise in treating hyperopia up to 3 D; however, there is still some concern about regression.
LTK has not developed much of a following during its investigational trials, and Dr. Teplick questioned its merits compared to the more predictable outcomes in laser procedures.
"It is not a good procedure in view of laser correction," Dr. Teplick said. "Laser correction seems to be much more predictable and is based on true measurements of the corneal curvature and true ablation of that curvature, rather than the application of heat to the cornea, which may or may not shrink the fibers this way or that."
In higher hyperopes, from 4 to 7 D, LASIK and PRK have been less predictable and carry a greater risk of loss of best-corrected visual acuity, Dr. Baker said. She tends to advise against these procedures for patients with higher degrees of hyperopia. For them, phakic IOLs may be a better solution.
Astigmatism
Many of the post-surgical concerns with higher levels of hyperopia also exist with higher degrees of astigmatism, Dr. Baker said. LASIK and PRK tend to be reliable up to 4 D of cylinder, but with 4 D to 7 D, patients will experience longer healing times, more fluctuation of vision and less predictable outcomes.
Another consideration in astigmatic patients is the amount of spherical correction needed to balance the ablation, she said.
"When judging how a patient with cylinder is going to do, you need to look at how much sphere there is to balance the astigmatism," Dr. Baker said. "If the patient is plano with 7 D of cylinder, that’s difficult, because the surgeon is operating to resolve only astigmatism. But if you have a patient who has 6 D of myopia and 2 D of astigmatism, you have more sphere to treat and that’s a much simpler type of correction with better outcomes."
The exact parameters of possible astigmatic correction may depend on the laser and the technique involved in the procedure, so optometrists should consult their surgery center to determine what degree of astigmatism is treatable, she said.
Overcorrections
LTK may be of use in overcorrected RK and LASIK patients, where previously there had not been a surgical solution, Dr. Teplick said.
"LTK is easy to do — you don’t have to make an incision, you can do it at the slit lamp and, for mild overcorrections, it may very well have a place. It’s relatively expensive technology if that’s all you’re using it for," he said.
The success of hyperopic LASIK also might eliminate this use for LTK, Dr. Teplick said.
"LASIK works very well for undercorrected RKs. I can’t see why it wouldn’t work well for overcorrected RKs," he said.
For Your Information:
- Cindy J. Baker, OD, comanaging director, can be contacted at the Laser Institute of the Rockies, 8400 East Prentice Ave., Ste. 1200, Englewood, CO 80111; (303) 793-3000; fax (303) 793-3008. Dr. Baker has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.
- Stanley B. Teplick, MD, can be contacted at the Teplick Laser Surgery Center, 9989 SW Nimbus Ave., Beaverton, OR 97008; (800) 422-7014; fax: (503) 520-0403; e-mail: teplick@europa.com. Dr. Teplick has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Louis J. Catania, OD, is president of Omega Institute, the educational affiliate of Omega Health Systems Inc., and can be reached at 2279 Seminole Rd. #4, Atlantic Beach, FL 32233; (904) 246-3900; fax (904) 247-8934; e-mail: catanial@omegahealth.com. Dr. Catania has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.