CASE PRESENTATION
Six years ago, a 34-year-old female underwent LASIK for 11.00 D of myopia (Figure 1). During the procedure a Moria M2 (Antony, France) microkeratome was used to create a 125-µm flap (calculated with subtraction pachymetry) and an Allegretto 200 Hz laser (Wavelight Laser Technologie AG; Erlangen, Germany), with a planned 6-mm optical zone, was used to conserve tissue. Total treatment centrally was planned to 130 µm. The residual cornea bed measured 320 µm. For 5 years after the surgery, the patient was satisfied, and plano, with 20/20 visual acuity. The patient now presents 20/40 UCVA and 20/20 BSCVA, with eyes measuring -1.50 D and -0.75 D. No ectasia is evident on the topography and Oculus Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany). Central cornea thickness is approximately 460 µm (Figure 2).
What will be your treatment plan, if any, in this patient?
Jorge L. Alió, MD, PhD
I would consider a LASIK enhancement, but only on the condition of studying the structure of the flap by anterior segment optical coherence tomography or very high-frequency ultrasound Artemis II measurement (Ultralink; St. Petersburg, Florida).
If the stromal bed is larger than 270 µm—which is likely—I would follow with flap elevation and LASIK. I would also consider creating a customized treatment because this patient should have spherical aberration electron as the first treatment. A customized treatment usually uses more cornea than regular standard treatments, and depending on the residual stromal bed, this must be handled carefully. I would not consider any other treatment modality. Alternatively, I would try to correct this residual sphere over the flap by transepithelial ablation and then use straightforward ablation to correct the eye with -1.50 D. I would use mitomycin C for 30 seconds in this case.
I have relatively extensive experience in cases like this, as I have seen many patients treated for high myopia in the past. None of my cases have developed any corneal ectasia. Additionally, a vast majority of these patients are happy and without complications after follow-up of more than 1 year.
A. John Kanellopoulos, MD
I have seen this type of LASIK regression many times in the past and have addressed the problem several different ways.
In some cases, I have relifted the flap to do an additional enhancement, after measuring the flap thickness intraoperatively in order to avoid significantly reducing the postenhancement residual stromal bed. (Since 2000, I have tried to adhere to the guideline of 270 µm for residual stroma following LASIK.)
Another potential method of treatment for this patient would be to perform a customized retreatment with asphericity adjustment as an additive (Wavelight 400 Hz Allegretto Wave Eye-Q laser). I would include a treatment goal of -0.50 D for the Q-value (asphericity), in order to reduce spherical aberrations that are typically induced during the correction of high myopes. The hope is that the postenhancement Q-value would be less positive. Through past experience, we have learned that correction of -10.00 D shifts the 30º asphericity of the cornea from an average -0.30 D to ±2.00 D, therefore inducing significant spherical aberrations.
In the case of this patient, I chose not to use either of the previously mentioned options. Considering that the cornea was stable, I pulled from my experience with UVA collagen cross-linking (CCL) as a means to rehabilitate ectatic corneas after LASIK. I proposed that the patient was experiencing a late biomechanical shift of the thinned cornea. The patient and I discussed the option of cross-linking the cornea and then enhancement, if necessary. I determined that performing an enhancement first may not be successful if the refraction continued to regress in the future. We, therefore, decided to proceed with collagen cross-linking with the PriaVision device (PriaVision, Menlo Park, California) for 30 minutes in conjunction with 1% riboflavin solution applied every 2 minutes to the surface of the deepithelialized cornea.
Initially, the patient was unsatisfied and experienced pain and discomfort for the first 10 days while the epithelium healed. That changed at 1-month follow-up, however, when we discovered her UCVA was back to 20/20 and her refractive error was -0.25 D. In the end, our patient achieved a visual acuity of 20/15. As seen in the comparison map of the posterior cornea surface (Figure 3), the left image is the pre-UVA CCL posterior cornea surface, which is devoid of any signs of ectasia. The middle map is the same posterior surface 1 month following UVA CCL. It is evident that there has been a flattening change in the mid-periphery of the posterior cornea.
I would, therefore, use this case to confirm previous reports on the biomechanical changes of the cornea following LASIK, and establish a significant biomechanical effect of the UVA cornea cross-linking to the operated cornea—with a change in the posterior cornea contour centrally and paracentrally. I believe this case shows that any surprise regressions noted—even years—after LASIK could be biomechanical changes of the cornea, and could be treated by this minimally invasive alternative.
Rui Martinho, MD; F. Falcão Reis, MD, PhD;
and Amandio A. Rocha-Sousa, MD
Primary consideration for this case must include the refractive stability of the patient, since we only would consider treatment once that is achieved. If refractive stability were achieved, we would treat the patient's right eye with LASIK. Our option is based on the actual corneal thickness of 460 µm.
We would use the Schwind Esiris (Schwind eye-tech-solutions, Kleinostheim, Germany) to treat the -1.50 D, with a corresponding ablation of 15 µm to 16.5 µm (considering an optical zone of the same 6 mm). Using the same 125-µm flap after the ablation, the residual thickness should be 319 µm, which is thick enough for the procedure and better than the inferior limit of 250 µm. The corneal aberrometry should also be considered. We assume that the Pentacam evaluation does not show abnormalities in the field, so we do not recommend a customized ablation (eg, ORK-CAM [Schwind eye-tech-solutions]). We also think that the same flap could be relifted for this second LASIK procedure.
Relifting the flap may be done easily within 2 years of a previous refractive surgery.1 A new LASIK flap, however, is required in cases with previously complicated surgery. Relifting the flap for LASIK retreatment is an effective and safe procedure. Two recent clinical cases show that the proper even management of the trauma and LASIK dislodged flap (from a surgery that occurred 7 years ago) may restore excellent visual acuity.2
Carlos M. Moedas, MD
Based on our present knowledge, the patient should have had a phakic IOL implanted, instead of undergoing LASIK for a -11.00 D correction. It seems that in this case, the LASIK procedure was used beyond the advisable limits.
Because this case is missing important data, like the initial K- or pachymetry readings, I wonder about this patient's present quality of vision. Any additional subtractive surgery (ie, LASIK, PRK) is not advisable, and alternatives, like phakic IOLs, are not available for such a low degree of ametropia.
As the other eye is only -0.75 D at the moment, I would suggest this patient wear spectacles or contact lenses, or opt for no correction. I would also tell the patient that her previous surgery has caused her cornea to become unstable and that her dioptric error will probably continue to increase.
As soon as that occurs, I would implant a phakic IOL on the right eye. Depending on the patient's anatomy and preferences, I would choose from either (1) a posterior chamber sulcus-supported ICL or (2) an anterior chamber iris enclavated IOL (Artiflex; Ophtec, Groningen, the Netherlands). Both lenses can be implanted under topical anaesthesia through a 3.2-mm incision. The patient should have at least 2,000 cells and a relatively deep anterior chamber (at least 2.8 mm). There are minor complications that prevent us from performing an ICL implantation, (ie, a weak zonula, because the patient was initially measured at -11.00 D). Additionally, a convex iris can cause chronic iris rubbing and is a contraindication to implanting an Artiflex lens.
Patient preferences and activities are also an issue, because some patients dislike seeing the lens on the anterior chamber. The patient in this case presentation may opt for an ICL, but she should be informed about the low risk of developing cataract.
Joaquim C. Murta, MD, PhD
Even with microkeratomes that create thin flaps and excimer laser programs that preserve corneal tissue, we should not treat 11.00 D of myopia with an excimer laser. With this in mind, I would not consider an enhancement (ie, LASIK, PRK, Epi-LASIK, other another modality), despite no apparent ectasia on the topography and Pentacam, and a central cornea thickness of 460 µm.
If the patient had developed 1.50 D of myopia within the last year, I would wait at least 9 months to 12 months, to know if this process is stable. Highly myopic patients develop cataracts earlier than the normal population, which could be the cause for this myopia change. If the refraction was stable after 9 months to 12 months, no alterations were observed at the slit lamp examination, and the patient firmly wanted to correct the -1.50 D, I would consider correcting her mild ametropia with two 0.25-mm intracorneal rings (Intacs; Additional Technology, Inc., Des Plaines, Illinois), implanted horizontally. This option is appealing because it is a reversible, noninvasive procedure.
Furthermore, implanting a phakic IOL could be an alternative procedure. Because the degree of myopia is small, however, I believe that it would not be worthwhile to take the risk of an intraocular surgery.
The patient has a UCVA of 20/40 in one eye and should have 20/30 or 20/25 in the other eye with a binocular UCVA of at least 20/30. Because this is not very disabling, spectacles or contact lenses are always possibilities.
Jorge L. Alió, MD, PhD, is Professor and Chairman of Ophthalmology, Miguel Hernandez University, Alicante, Spain and Medical Director of VISSUM Corp., in Spain. Professor Alió is a consultant and receives grant support from Schwind-eye-tech-solutions. He may be reached at +34 96 515 00 25; jlalio@vissum.com.
A. John Kanellopoulos, MD, is Director of Laservision Eye Institute in Athens, Greece. He is Attending Surgeon for the Department of Ophthalmology at the Manhattan Eye, Ear, &Throat Hospital in New York and Clinical Associate Professor of Ophthalmology at New York University Medical School. He is a member of the CRST Europe Editorial Board. Dr. Kanellopoulos may be reached at +30 21 07 47 27 77; laservision@internet.gr.
Rui Martinho, MD, and Amandio A. Rocha-Sousa, MD, are consultants at S Jo„o Hospital at the University of Porto, in Portugal. F. Falcão Reis, MD, PhD, is Professor and Head of the Ophthalmology Department at S Jo„o Hospital. Dr. Rocha-Sousa may be reached at arsousa@med.up.pt. Both did not supply financial disclosure information.
Carlos M. Moedas, MD, is a Consulting Ophthalmologist at the Hospital Particular, in Algarve, Portugal. Dr. Moedas states that he has no financial interest in the any of the products or companies mentioned. Dr. Moedas may be reached at +35 19 68 19 44 95; cmoedas@mail.telepac.pt.
Joaquim C. Murta, MD, PhD, is an Assistant Professor at the University Hospital Coimbra, in Portugal. Dr. Murta states that he has no financial interest in any of the products or companies mentioned. He may be reached at +352 239 701182; jmurta@netcabo.pt.
Jérôme C. Vryghem, MD, is from the Brussels Eye Doctors in Brussels, Belgium. Dr. Vryghem is a member of the CRST Europe Editorial Board. He states that he has no financial interest in any of the prodcuts or companies mentioned. He may be reached at +32 2 741 69 99; j.c.vryghem@vryghem.be.
Up Front | Apr 2007
Retreating a Highly Myopic Patient
Jorge L. Alió, MD, PhD; A. John Kanellopoulos, MD; Rui Martinho, MD; F. Falcão Reis, MD, Phd; Amandio A. Rocha-Sousa, MD; Carlos Moedas, MD; and Joaquim C. Murta, MD, PhD
