Scarring and Irregular Astigmatism After Trauma to LASIK Flap

By David R. Hardten, MD; Mitchell A. Jackson, MD; Gaston O. Lacayo III, MD; George O. Waring IV, MD; and Elizabeth Yeu, MD
 

A 42-year-old woman suffered a scratch to her left eye from a tree branch 5 months ago. Prior to this event, she had a UCVA of 20/15 OU after undergoing LASIK for myopia 10 years earlier. Either epithelium or vegetable matter was visible under the flap (Figure 1A). High magnification showed a full-thickness linear scar in the LASIK flap and white material (epithelium with or without vegetable matter) to the left (Figure 1B).

Because the patient’s vision was markedly blurred, the surgeon took her to the minor room, lifted the flap, removed the debris, and placed a bandage contact lens, which remained on the eye for a month. A full-thickness paracentral laceration was clearly visible in the lifted LASIK flap. Scarring was evident in the laceration with residual epithelial cells (Figure 1C and D).

At the current examination, the epithelial cells have died, leaving a scar. Her BCVA is 20/25 OS with the same refraction listed on topography (Figure 2). A paracentral island is causing irregular astigmatism and ghosting of vision.

How would you proceed?

—Case prepared by Kenneth M. Goins, MD.

DAVID R. HARDTEN, MD

Unfortunately, this patient has significant scarring and irregular astigmatism after trauma to the flap. A nonsurgical option would be to try a rigid gas permeable (RGP) contact lens, although I suspect that the patient’s vision would still be suboptimal. Because the scar is quite dense and fully transects the LASIK flap, phototherapeutic keratectomy (PTK) to remove the scar would be quite deep, and it would be difficult to maintain refractive neutrality during a PTK procedure.

Because the scar was found to be only in the LASIK flap when it was lifted and not to involve the deeper stromal bed, my initial approach would be to remove the flap, perform a light “dusting” with PTK (4-6 μm broadly to all areas), and use a diamond bur to polish down the area of the hinge. I would apply mitomycin C (MMC) 0.2 mg/mL or 0.02% solution to the bed for 60 to 90 seconds. I would have the patient use steroids frequently postoperatively. Nine to 12 months later, when the refractive error was stable, her residual refractive error could probably be treated with wavefront-guided excimer laser correction,1 because there is likely to be some residual astigmatism and ametropia, especially if the LASIK flap was not created with a femtosecond laser.

If this intervention did not provide adequate vision, the patient could again attempt to wear an RGP contact lens. If the result were still suboptimal and further laser treatment were not expected to help, then a deep anterior lamellar keratoplasty could be performed. I would think, however, that the patient could obtain adequate vision without keratoplasty.

MITCHELL A. JACKSON, MD

The presenting patient brings many challenges to the surgeon in that her expectations will be high. Patients somehow forget the original trauma as the cause and remember only their last surgical procedure. Adjusting her expectations to a reasonable level before any further treatment will therefore be of the utmost importance to reduce the surgeon’s risk of a malpractice lawsuit.

I approach cases such as this one very conservatively at first. Because the patient is at least of early presbyopic age, if her injured eye is nondominant, then she may find her myopic spherical equivalent of -2.25 D tolerable as a monovision setup. Typically, near vision is better than distance vision in early presbyopes with irregular corneas, so this option may be realistic. If not, the next conservative approach would be to conduct a contact lens trial (especially if the affected eye is nondominant) to achieve a distance BCVA of 20/25, as reported here. This result might be tolerable with bilaterally functional vision for distance.

As for surgical options, the highest probability of success would be with truly topography-driven excimer laser surface ablation, a procedure not yet available in the United States. The closest option, approved by the FDA as a humanitarian device exemption in December 2001, would be the use of the Visx Custom Contoured Ablation Pattern treatment (C-CAP; Abbott Medical Optics Inc.). Used for surface ablation in a transepithelial fashion, the C-CAP method is designed to treat offcenter ablations that appear as paracentral islands, as in this case. I would apply MMC 0.02% after the ablation was complete to minimize the risk of further postoperative haze/scarring. I would also prescribe cyclosporine ophthalmic emulsion 0.05% (Restasis; Allergan, Inc.) for at least 6 months postoperatively to serve as an immunomodulator in an effort to minimize corneal haze.

A more aggressive surgical option, which could be considered a last resort, would be to create a free cap and perform an autorotation to try to remove the scarred area from the visual axis. In my opinion, this procedure would be extremely difficult and dangerous due to the traumatic, full-thickness laceration of the flap. Any rotation would therefore most likely splay that weakened area farther open and create more irregularity in the corneal surface. A final but plausible surgical option would be to amputate the flap and wait for full surface re-epithelialization, with the use of MMC 0.02% and cyclosporine to prevent corneal haze postoperatively. After a minimum of 3 to 6 months for healing, the surgeon could then decide on the next step for the patient.

GASTON O. LACAYO III, MD

The primary issue is managing the irregular astigmatism induced by the corneal trauma. An evaluation of the Nidek OPD-Scan (Nidek, Inc.) shown in Figure 2 reveals a paracentral area of irregular astigmatism just nasal to the visual axis. If the LASIK interface is stable and there is no progression of epithelial cells or scarring, I would consider multiple options for rehabilitating the patient’s vision. First, I would offer a contact lens. An RGP lens should reduce the irregular corneal astigmatism and help achieve her BCVA. Alternatively, a scleral lens could improve her vision by reducing the effects of the corneal opacity. A soft contact lens would also be an option to reduce the refractive error, but it usually cannot correct ghosting.

If a contact lens were unsuccessful or the patient preferred a more aggressive approach, I would consider surface ablation. Although it would be the ideal procedure to reduce the irregular astigmatism in this case, topographyguided surface ablation treatments are not currently available in the United States. A full-thickness laceration and scar could be treated like a buttonhole LASIK complication. I would apply 20% ethanol on a circular sponge for up to 60 seconds and carefully debride the epithelium over the defect. Next, I would treat the manifest refraction on the OPD scan and apply MMC 0.02% after the treatment over the residual stroma for 1 minute. The patient would then wear a bandage contact lens for 1 week and taper a steroid drop over 4 to 6 weeks.

GEORGE O. WARING IV, MD

Fortunately, the patient did not develop an infection, and it seems as though the epithelial ingrowth has been managed. A further diagnostic workup should include high-resolution optical coherence tomography to better define the etiology of the irregular astigmatism (ie, scar of the lamellar flap, stromal bed irregularity, residual epithelial ingrowth, interface fluid). Scheimpflug photography and tomography with elevation maps would also be useful.

A discussion of surgical and nonsurgical options would ensue. I would perform an RGP lens overrefraction and trial for both diagnostic and therapeutic purposes. A scleral shell contact lens would also be worth considering if a standard RGP lens did not work. If the patient were highly motivated for surgical correction, pending the results of the aforementioned workup, I would carefully outline for her the risks, benefits, possible need for additional surgery, and—most importantly— what reasonable expectations she should have. I would document this discussion in her chart and informed consent.

Once a therapeutic surgical approach were chosen, I would recommend amputation of the flap with a minimum healing period of 6 months. After achieving stable serial refractions and topographies, I would perform advanced, customized, wavefront-guided surface ablation with an extended application of MMC or a limited topography-guided PRK (once this procedure is available in the United States). If the patient were still symptomatic, an RGP or scleral shell lens could be attempted again to address residual astigmatism. If this were insufficient, a deep anterior lamellar keratoplasty could be considered.

ELIZABETH YEU, MD

I would perform an overrefraction with an RGP contact lens to see if it improved the patient’s BCVA; it should since the central visual axis appears to be clear. If this were effective, medical options could include an RGP lens or BostonSight Prose (Boston Foundation for Sight), possibly with a miotic agent such as pilocarpine or brimonidine tartrate ophthalmic solution (Alphagan; Allergan, Inc.) to help alleviate the ghosting of images through pupillary constriction.

Before considering any surgical intervention, I would wait at least 6 months from the original lifting of the flap and scraping to make certain that the epithelial downgrowth did not recur. The densest part of the scar appears to be at the 6-o’clock position. This may or may not be the greatest contributor to the ghosting of images that the patient is experiencing. Topography demonstrates that the actual “body” of the laceration, which is temporal to the corneal center, is causing most of the irregular astigmatism and elevation.

Surgical treatment will likely be a staged process—first potentially to remove the source(s) of the irregular astigmatism and problems with image quality and, second, to treat the residual refractive error. Anterior segment optical coherence tomography would help determine the depth of the scar, including the densest area inferiorly. If the scar is not too deep overall and a wavefront-guided scan could be captured (which seems doubtful), staged surgery might be an effective option.

Topography-guided PRK (or PTK) might be another initial option to smooth over the irregular elevation. An overall myopic treatment might be required to remove a greater depth of the dense scar tissue itself. MMC 0.02% should be used intraoperatively for 30 to 60 seconds to prevent the formation of haze from the recently activated keratocytes/fibroblasts. I would then wait at least 6 months before performing any hyperopic PRK for visual correction.

If the patient continued to complain about the quality of her vision as a result of some residual scarring, the surgeon could eventually consider amputating the flap or performing a lamellar keratoplasty to remove the scar in its entirety. These, however, are fairly drastic options.

Section Editor Stephen Coleman, MD, is the director of Coleman Vision in Albuquerque, New Mexico. Section Editor Parag A. Majmudar, MD, is an associate professor, Cornea Service, Rush University Medical Center, Chicago Cornea Consultants, Ltd. Dr. Majmudar may be reached at (847) 882-5900; pamajmudar@chicagocornea.com.

Section Editor Karl G. Stonecipher, MD, is the director of refractive surgery at TLC in Greensboro, North Carolina.

David R. Hardten, MD, is the director of refractive surgery at Minnesota Eye Consultants in Minneapolis. Dr. Hardten may be reached at (612) 813-3632; drhardten@mneye.com.

Mitchell A. Jackson, MD, is the founder and director of Jacksoneye in Lake Villa, Illinois. He is a member of the speakers’ bureaus for Abbott Medical Optics Inc. and Allergan, Inc. Dr. Jackson may be reached at (847) 356-0700; mjlaserdoc@msn.com.

Gaston O. Lacayo III, MD, is in private practice at the Center for Excellence in Eye Care in Miami, and he is an assistant professor with the Department of Ophthalmology at Rush University Medical Center in Chicago. He acknowledged no financial interest in the product or company he mentioned. Dr. Lacayo may be reached at (305) 598-2020; gaston_lacayo@rush.edu.

George O. Waring IV, MD, is the director of refractive surgery for the Storm Eye Institute and an assistant professor of ophthalmology at the Medical University of South Carolina in Charleston, South Carolina. He is also the medical director of Magill Vision Center in Mt. Pleasant, South Carolina. Dr. Waring may be reached at georgewaringiv@gmail.com.

Elizabeth Yeu, MD, is an assistant professor of ophthalmology for the Cullen Eye Institute at Baylor College of Medicine in Houston. She acknowledged no financial interest in the product or company she mentioned. Dr. Yeu may be reached at (713) 798-5143; eyeulin@gmail.com.

Sun R, Hardten DR, Lindstrom RL, Davis EA. Treating stable corneas: wavefront-guided treatments for irregular astigmatism. In: Wang M, ed. Irregular Astigmatism: Diagnosis and Treatment. Slack, Inc.: Thorofare, NJ; 2008:149-162.

 

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