Refractive Options: What Would You Choose?
Presented with varying scenarios for candidates for refractive procedures, top surgeons offer their strategies.
CASES PROVIDED BY PAUL S. KOCH, MD, EDITOR EMERITUS OF OPHTHALMOLOGY MANAGEMENT AND ERIC D. DONNENFELD, M.D., OM EDITORIAL BOARD MEMBER.
Refractive surgeons have never had so many options before them, and as a result, patient outcomes are better than ever. However, as technology advances and techniques change, selecting the technique to achieve the best outcome is also more complicated. With this in mind, Ophthalmology Management recently took the opportunity to speak to several refractive surgery specialists to find out how they are currently treating patients who seek refractive correction.
The design is simple: We presented the same five cases to each surgeon and then listened to what they had to say. In some instances, the answer is quick and easy. In many instances, alternatives and caveats are provided. Informed consent and preoperative evaluation, including careful consideration of K readings and corneal thickness, are commonly cited as key. To follow are the verbatims from our distinguished panel.
The panel:
Y. Ralph Chu, M.D., is founder and medical director of Chu Vision Institute in Edina, Minn., and is adjunct assistant professor of ophthalmology at the University of Minnesota. He is a consultant for Advanced Medical Optics and Visiogen. |
Thomas V. Claringbold II, D.O., is chief ophthalmologist for MidMichigan Physicians Group in Clare, Mich., and is associate clinical professor, department of Nuerology and Ophthalmology at Michigan State University and department of Sports Medicine at Central Michigan University. He has no financial interest in the information contained in this article. |
Eric D. Donnenfeld, M.D., is medical director of TLC Laser Centers in New York and Connecticut and a partner with Ophthalmic Consultants of Long Island. Dr. Donnenfeld is a consultant to AMO, Alcon and Bausch & Lomb. Dr. Donnenfeld is a member of the Ophthalmology Management editorial board. |
P. Michael Mann, M.D., is director and founder of the Mann Eye Institute in Houston, Texas. He has no financial interest in the information contained in this article. Dr. Mann is a member of the Ophthalmology Management editorial board. |
Jay S. Pepose, M.D., Ph.D., is medical director of the Pepose Vision Institute in St. Louis, Mo., and professor of clinical ophthalmology at Washington University School of Medicine and Barnes-Jewish Hospital. He is a consultant for Bausch & Lomb. |
Case #1 |
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Refraction: -10 D OD/-3 D OS @ 10° Pachymetry: 600 μm Topography: Normal. |
Y. Ralph Chu, M.D.: I use -10 D as a general cut-off for consideration of laser vision correction (LVC), so for this patient I would discuss a phakic IOL. To correct the astigmatism, I would recommend a limbal relaxing incision (LRI) at the time of IOL implantation. I will also talk to patients about the possibility of using LASIK or PRK to address any residual astigmatism after the phakic implantation. For older patients, I typically recommend PRK as an enhancement technique to reduce the risk of epithelial injury and dry eye postoperatively. I wait about 3 months after the first surgery for the refraction to stabilize.
The phakic implant that I choose depends on the size of the patient's eye. If there is enough room in the anterior chamber, I may use the Verisyse (Advanced Medical Optics [AMO], Santa Ana, Calif.), but many patients prefer the smaller incision that I am able to offer with insertion of the Visian ICL (STAAR Surgical, Monrovia, Calif.).
Thomas V. Claringbold II, D.O.: I have been treating up to -11 D with LASEK and use surface procedures for 100% of my LVC procedures. However, the age of the patient would have an effect on my choice. Going simply on prescription alone (no social factors, i.e., occupation or lifestyle) I would probably recommend the following: for patients 21 to 35 years of age, LASEK alone; for patients 36 to 50 years of age, either LASEK alone or a bioptics procedure (a phakic implant and LASEK) to correct residual refractive error; and for patients older than 50 years of age, a bioptics procedure.
Eric D. Donnenfeld, M.D.: If the patient has a regular topography and the cornea is thick enough to perform LASIK, then considering the results that we are achieving now with custom ablation using wavefront technology and thin-flap LASIK, I'm happy to do patients up to the upper level of the FDA guidelines of 11.5 D of myopia. The FDA requires that at least 250 μm of tissue exists at the conclusion of a case. I think most ophthalmologists, myself included, are more conservative than the guidelines. I'd probably want to leave at least 275 μm behind.
Alternatively, I might also consider doing a bioptics procedure in which I implant a phakic IOL and do a postop LASIK enhancement for the 3 D of cylinder, which is too much for a reliable LRI. However, I think that phakic IOL implantation is a more invasive procedure and would most likely choose the thin-flap LASIK.
P. Michael Mann, M.D.: In my experience,�patients who need this level of correction typically get a better visual result with a phakic IOL. However, this patient has too much astigmatism to correct with an LRI so, assuming this patient has a normal topography, I would correct this patient with a bioptics procedure utilizing LASIK with IntraLase (AMO).
Jay S. Pepose, M.D.: Studies have shown that patients with over -10 D spherical equivalent generally obtain a better UCVA, gain more lines of vision, and have better contrast sensitivity with phakic IOL implantation compared with patients who have undergone LASIK. The placement of the phakic IOL closer to the nodal point of the eye than LASIK increases its effective functional optical zone to a diameter larger than the implant diameter itself when translated to the corneal plane, and larger than the functional optical zone obtained with LASIK for a similar correction.
With these potential advantages in mind, patients must still be evaluated to determine whether they are a good candidate for a phakic IOL. Relevant determinations include adequate endothelial cell count adjusted for age, and anterior chamber depth of at least 3.2 mm for Verisyse and 3.0 mm for Visian. Finally, topography that rules out forme fruste keratoconus is required if a bioptics procedure or a LASIK enhancement is to be considered. In this case, I would plan on a bioptics procedure and first create a corneal flap. Then, 2 weeks or later I would proceed with a phakic lens implant, orienting the entry wound along the steepest axis of astigmatism. Any residual refractive error would be addressed with flap lift and laser treatment after postoperative stability is achieved. If preoperatively, the patient had a markedly dry eye or particularly thin cornea, a phakic IOL followed by a LASEK or PRK enhancement, if needed, would be a reasonable approach to this patient's refractive error.
Case #2 |
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Refraction: -6.50 D OD/-2.00 D OS @ 80° Pachymetry: 498 μm Topography: Normal |
Dr. Chu: For corneal pachymetry under 500 μm, I usually consider surface ablation. For somebody who has this degree of near sightedness, we would use mitomycin C treatment. In this situation, even if the topographies were normal, I would still lean toward surface ablation over LASIK.
Dr. Claringbold: I would have no problem using LASEK for this case. I would not use mitomycin C, rather, I would prescribe oral 1,000 mg vitamin C q.d. from the time the course was chosen until approximately 4 to 6 months postop.
Dr. Donnenfeld: In the past I would have recommended PRK for this patient, however, I am now beginning to realize that for some patients, thin-flap LASIK is actually a safer procedure. For this patient, assuming that the topo�graphy was normal, I would discuss the options of either PRK or thin-flap LASIK and document with informed consent. While PRK is as an option, the risk of infection is greater with a surface procedure. Additionally, the risk of ectasia is so small in this patient that I would feel very comfortable doing thin-flap IntraLase LASIK. I would make an IntraLase flap of 90 μm to 100 μm, leaving a corneal stroma of approximately 400 μm. The ablation itself would be approximately 80 μm to 90 μm, leaving a bed of 310 μm, which I find acceptable. I would suggest a custom ablation as well.
Caveats for this case are that patient must have normal topography, unchanging refraction and be at least 22 years of age. I wouldn't do this for a younger patient.
Dr. Mann: This patient has a thinner cornea than average and a high level of correction — two risk factors for postop ectasia.�The age of this patient needs to be known in order to determine the best treatment option.�In a patient older than 45 years of age, I would consider doing advanced surface ablation with mitomycin. I would encourage a younger patient to either have a phakic IOL implanted with an LRI or wait for a toric phakic IOL to become available.
Dr. Pepose: I would offer this patient surface ablation with prophylactic mitomycin C treatment. I would carefully examine both eyes of the patient and the corneal topographies for any signs suggestive of keratoconus or forme fruste keratoconus. While this is part of the standard evaluation for all refractive patients, those with central pachymetry below 500 μm deserve special attention and scrutiny. If such signs were found, I might still consider an off-label laser surface ablation with prophylactic mitomycin C or, alternatively, a phakic IOL followed by a customized astigmatic surface ablation to minimize tissue removal. This would occur after an extensive discussion with the patient about the inherent risks and benefits, including but not limited to the possibility of developing frank keratoconus with or without any surgical treatment. This informed consent process would be thoroughly documented.
This patient's cornea may be too thin to comfortably perform a wavefront-guided LASIK procedure, even planning for a very thin or an ultrathin flap. It is safest to allow for two times the standard deviation of the flap thickness variation created by the femtosecond laser or the latest generation microkeratome employed. This could lead to a flap bed approaching or below 250 μm in this case, potentially increasing the risk for ectasia and limiting the possibility of enhancement if needed.
Case #3 |
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Refraction: -9.25 D sphere Pachymetry: 475 μm Keratometry: 43.0/43.0 Topography: Normal |
Dr. Chu: This case would require more discussion with the patient concerning their thin cornea — 475 μm — and flat Ks, both which could result in potential problems in terms of quality of vision, i.e., loss of contrast, post-LASIK or post-PRK. I would discuss with the patient the option of no surgery. If surgery was the desired option, then I would educate the patient about phakic IOLs and, depending on the patient's age, other types of lens implants.
Dr. Claringbold: Again, age may influence my decision for this patient, but I most likely would do LASEK. Assuming normal topography, after nomogram adjustment for LASEK I would only be treating -7.5 D and from the corneal measurements provided I would be left with over 300 μm.
Dr. Donnenfeld: For this case, assuming that the ablation would be somewhere around 140 μm in depth, with my current laser, it would leave me with a residual bed of 335 μm, which is too thin for me. I would not be comfortable with a PRK in this patient, and because this patient has minimal astigmatism, this patient is an ideal candidate for a phakic IOL.
Dr. Mann: Regardless of the age of this patient, the best visual outcome would result with a phakic IOL.
Dr. Pepose: In my opinion, this patient is best suited for a phakic IOL, assuming that they meet the other criteria for this discussed previously. I do not consider LASIK in any patient with central corneal thickness below 480 μm. The risk of developing corneal haze is slightly higher with deeper ablations (over 100 μm or 18% of corneal thickness) and can occur despite the use of prophylactic mitomycin C. Wavefront-guided laser treatment of this case would remove on the order of 135 um for a 6-mm optical zone treatment and this represents removal of around 28% of the corneal thickness. Comparative studies suggest that a phakic IOL may produce better contrast sensitivity and a larger effective functional optical zone than LVC of this magnitude.
Case #4 |
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Refraction: +4.5 D Keratometry: 44.00/44.00 Topography: Normal Notes: Trace nuclear sclerosis and BCVA of 20/20 Age: 52 years |
Dr. Chu: I would consider clear lens extraction in this case. We have found that even it we can get a patient with this degree of hyperopia to 20/20 with LVC, quality of vision is better with an IOL. This patient has early cataracts and is in the right age group for a presbyopia-correcting IOL. This could be done as a clear lens extraction. If the patient has visual complaints consistent with their cataract lens changes and there were other objective signs of visual loss (glare testing), then this patient may be considered for cataract removal with lens replacement. The patient would always have the option of waiting for the lens changes to worsen before considering any surgery.
Dr. Claringbold: Clear lens extraction is what I would offer this patient. My official cut-off for hyperopic LASEK is 3 D. I had a similar patient who was 25 years of age. We did treat 3 D hyperopia with LASEK and she is easily able to accommodate the remainder and is 20/20 uncorrected. We did an extensive preop consent on what she is to expect as she approaches 40 years of age.
For the patient in the case presented, I would choose clear lens extraction and implant a premium IOL.
Dr. Donnenfeld: My decision for this case depends on the informed consent, the visual needs of the patient and the keratometry readings. There are three options that I think are good. For reduced dependence on glasses, a multifocal IOL may be appropriate, but if the patient wants to have the least invasive procedure, LASIK would be a reasonable alternative. If the patient wants the clearest distance vision and does not mind reading glasses, then I would recommend clear lens extraction and implantation with an aspheric IOL.
I use a modified Dell questionnaire with patients to help determine what is the best option for them. I talk to patients about what their needs are and about their aversions to risk are. Some patients won't even consider an intraocular procedure and others prefer to eliminate the risk of getting cataracts down the road.
Dr. Mann: In my experience, a clear lens exchange with a premium IOL is the best choice of treatment in this case. I have performed LASIK on these type of patients, and the visual outcome can often be affected by dry eye syndrome. It is important to educate the patient about the expected outcome from the premium IOL in order to achieve the patient's expectations.
Dr. Pepose: I would assess the functional impact of the early cataract, test high and low contrast visual acuity with glare and evaluate the quality of the centroids on wavefront analysis. While LASIK is an option, the potential for progression of the cataract and regression of the LASIK effect needs to be carefully considered, particularly given the substantial hyperopic treatment. After a thorough discussion about the potential risks, benefits and alternatives of intraocular surgery, I would offer clear lens extraction, which generally results in high quality vision with a greater long-term effect. This would include the option of implanting a premium IOL, which would afford a greater range of functional vision.
Case #5 |
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Refraction: +0.75 D, -1.25 D @ 70° Notes: Post-multifocal IOL, desires correction of residual error Age: 65 years |
Dr. Chu: I would recommend LVC. For a patient of this age, I would lean toward conventional PRK. Because of the low degree of refractive error and the potential of difficulty achieving an accurate wavefront analysis, a custom treatment would not be necessary.
Dr. Claringbold: In my opinion, an LRI is not precise enough for this case. I prefer to use an LRI at the time of cataract surgery and then address residual cylinder postop with the laser. I have had good results with conventional LASEK and would not recommend custom ablation because the registration capture for custom can be difficult with the multifocals. By using conventional surface ablation, I am confident that I will not induce aberrations for this case.
Dr. Donnenfeld: For this patient, who has already had a multifocal IOL with a spherical equivalent of 0.1 D postop, the easiest, most cost-effective procedure is an LRI.
I would let the patient know that LASIK or PRK would offer more precise correction and, based on the adhesion of the epithelium, these procedures would also be appropriate. However, if an LRI doesn't produce the desired results, we can always go back and do an LVC later. All things considered, I would choose an LRI as my first option.
Dr. Mann: I would first carefully evaluate this patient for dry eye and start this patient on topical cyclosporine A (Restasis, Allergan) and a mild steroid ointment at night for 4 to 6 weeks, then re-evaluate this patient to set his expectations for a post-LASIK outcome. I would then perform LASIK with the IntraLase and the Allegretto Wave (Wavelight, Erlangen, Germany) with wavefront-optimized technology. In my experience, patients with similar profiles have been very happy with this method of treatment.
Dr. Pepose: Patients who have had a multifocal lens implant expect good unaided vision postoperatively. In this patient with mixed astigmatism, the results of LVC, in my hands, are more predictable than LRIs. I would assess the patient's ocular surface, corneal thickness, topography and dry eye status. If the patient had dry eye, rapid tear breakup, a thin cornea, or atypical topography, I would favor a surface laser ablation. Otherwise, I would proceed with LASIK, given the more rapid visual recovery. Because not all wavefront analyzers have been optimized or validated for measurement of eyes with different multifocal IOLs, I generally utilize conventional ablation profiles in most cases. OM