Refractive Surgery | Jun 2005
Flap Melt After a Corneal Transplant
Elizabeth A. Davis, MD, FACS; D. Matthew Bushley, MD; Terry Kim, MD; Parag A. Majmudar, MD; and Herbert E. Kaufman, MD
A 48-year-old male presents with an ocular history of a corneal flash burn from a lightening strike and a corneal thermal burn in his left eye in 1986. He underwent phototherapeutic keratectomy (PTK) for the corneal scar in 1995 and received a corneal transplant for a penetrating injury in 1996. The patient underwent LASIK in 1999 to address his residual myopia and astigmatism, and he received a LASIK enhancement in 2004.
After this retreatment, the patient developed herpetic simplex stromal keratitis, mainly involving the flap with associated flap melt. After antiviral treatment and prophylaxis, his eye has remained quiet for 6 months (Figure 1). The corneal transplant remains clear, but tissue of the flap has eroded away from it. The patient's UCVA is 20/200 OS, and his BCVA is a poor 20/60 OS. The referring ophthalmologist placed punctal plugs in the patient's upper and lower puncta in an effort to maintain a quality tear film, which currently appears to be healthy. Attempts to fit contact lenses have been unsuccessful secondary to the irregular corneal surface after the corneal flap melt.
The patient's medical history is normal. Although his UCVA is 20/20 OD, his current line of work requires a UCVA of 20/40 or better bilaterally. The patient requests options for improving the vision of his left eye.
ELIZABETH A. DAVIS, MD, FACS
Because the patient is intolerant of contact lenses and desires improved vision, the only options are surgical. Additional laser ablation via LASIK or PRK is unlikely to be of benefit given the eye's irregular astigmatism and poor BCVA. Nevertheless, if it is possible to obtain a wavefront measurement, one could attempt a treatment with the excimer laser. Due to his previous history of a flap melt, I would prefer to perform PRK and use mitomycin C (MMC) 0.2mg/mL for 1 minute to prevent haze. I would have the patient continue oral acyclovir throughout the pre- and postoperative period. I might even consider a temporary lateral tarsorrhaphy to aid epithelial healing. Of course, this patient is at risk of a complete corneal melt, as I would be careful to warn him.
If it were not possible to obtain a wavefront measurement or if the map obtained contradicted objective findings such as the manifest refraction, I would consider amputating the flap, applying MMC for 1 minute, and allowing re-epithelialization. After 3 months, I would reattempt measurements in preparation for surface laser ablation, again coupled with the use of MMC.
If all of these efforts failed, I would consider a corneal transplant. A lamellar graft is an option given the apparently normal endothelial function of the current graft, but I would prefer to perform penetrating keratoplasties. Although more invasive, they eliminate the risk of interface haze with a lamellar graft. I would have the patient continue oral acyclovir pre- and postoperatively, and I would perform a temporary lateral tarsorrhaphy.
The goal of 20/40 UCVA in this eye is a bit lofty, considering the level of irregular astigmatism and the risk of recurrent herpes simplex virus after a surgical intervention. I would advise the patient that the likelihood of such a refractive outcome is low. Even if a corneal graft were successful, achieving a UCVA of 20/40 might require a subsequent laser keratorefractive procedure, again risking the recurrence of the same problem that led to this presentation.
D. MATTHEW BUSHLEY, MD, AND
TERRY KIM, MD
In light of this patient's history of multiple ocular traumas and surgeries, the current approach needs to begin with a comprehensive ocular examination to look for other potential causes of decreased vision (ie, cataract and macular pathology). Assuming the findings are normal, one might consider a repeat contact lens trial with an experienced fitter and expect it to result in vision that is 20/40 or better if the patient's central cornea is clear and the visual loss is secondary to irregular corneal astigmatism.
If the contact lens fitting is unsuccessful, the next option is surgical intervention to address the irregular astigmatism, variable corneal thinning, and LASIK flap melt. Because only the flap is involved in the corneal melt, we would amputate the flap, apply MMC 0.02% for 30 seconds to reduce the risk of haze, and taper topical steroids over several months. Visual results in patients with LASIK flap amputation have been reported to be variable with the possibility of significant irregular astigmatism or surface irregularity.1 Rigid contact lens wear or possibly one or more PTKs may be necessary to achieve the desired visual acuity. Alternatively, one could initially consider an anterior lamellar keratoplasty procedure with either a microkeratome or a femtosecond laser, but we feel that it would have a limited visual outcome based on the opacification of the interface. A last resort would be a repeat penetrating keratoplasty.
Prior to any procedure, we would ensure that the patient's eye was quiet for 6 to 12 months and would have him begin topical prednisolone acetate preoperatively to control inflammation and vascularity. Postoperatively, we would add a systemic antiviral agent (acyclovir 400mg orally b.i.d.) for 1 year and fit the patient with spectacles (polycarbonate lenses) or a contact lens to achieve the desired visual acuity of 20/40 or better.
PARAG A. MAJMUDAR, MD
Although a contact lens fitting was not successful due to surface irregularity, knowing the patient's BCVA with a rigid gas permeable lens would help to establish the visual potential in this eye. Because the tear film appears healthy, it is unlikely that the patient's intolerance of contact lenses is a consequence of dry eye syndrome but rather is due to the corneal irregularity. One might try fitting a Boston Scleral Lens (The Boston Foundation for Sight, Needham, MA). Because this lens is sclerally supported, the corneal curvature may play a lesser role in the patient's adaptation to the lens. If a contact lens fitting of any variety is not possible, a surgical solution is all that remains.
There are three major surgical options. The least invasive course is a wavefront-guided PRK procedure, assuming that the wavefront aberrometer can capture this irregular cornea. I would use MMC prophylaxis (0.02% for 30 seconds) to prevent haze. If the aberrometer could not adequately analyze this cornea, amputating the flap might be an option. This patient would require close observation for the development of haze. Another graft would be a last resort.
Before any surgical intervention, the patient should undergo a thorough informed consent discussion that addresses the possibility of herpetic reactivation. Prophylaxis with oral and/or topical antivirals is indicated, preferably 2 weeks prior to surgery and for several months postoperatively.
HERBERT E. KAUFMAN, MD
Lightning strikes often coagulate the epithelium rather than burn the stroma. These coagulations can completely obscure vision, but they can be rubbed off as the epithelium rubs off and leave good visual acuity. Because this patient clearly had dry eyes and has had an unhealthy tear film, it is questionable whether he had herpes simplex stromal keratitis or whether the flap melt may have been associated with exposure and drying. When the eye is really dry, almost any treatment can be beneficial because it provides moisture. In addition, based on the topography, he has good predicted visual acuity with spectacles and perhaps with Alphagan (Allergan, Inc., Irvine, CA).
The ocular surface is not dry at present, but possible intermittent drying from lagophthalmos could be the problem. If the cornea seems dry after the placement of bilateral upper and lower punctal plugs and the tear film seems reasonable, the ophthalmologist should suspect lagophthalmos, which must be managed with ointments or occlusive goggles. I would want to rule out any possible surface exposure before deciding on an additional therapy. If the patient does not have lagophthalmos, I would still aggressively treat his ocular dryness.
There is little penalty in removing an irregular flap. The cornea below is usually smooth, and, when it re-epithelializes, it is generally capable of providing excellent vision. If the patient still could not see well after removal of the flap, I would try fitting some of the more sophisticated contact lenses (eg, scleral-supported lenses). With the patient's history of a penetrating injury, moreover, it is important to know that his vision as corrected by contact lenses is in fact better than 20/40, even if the contact lens can be worn only with difficulty. The good predicted visual acuity from topography and the poor achievable acuity make it necessary to rule out retinal damage from the perforating injury.
If corneal opacification remained after amputation of the flap, I would remove additional superficial cornea with a microkeratome and either glue or sew on a microkeratome-cut piece of donor cornea.2 If the corneal bed were insufficient, I would undermine the edges of the flap bed and attach a thicker (0.3µm or greater) microkeratome-obtained lamellar piece or a lathe-cut piece of donor cornea (Cryo-Optics, Houston, TX) and use interrupted sutures. This technique gives strength to the cornea that a LASIK flap without sutures lacks, and its smoothness is comparable to that after PTK.
The advantage of using a microkeratome, Intralase FS laser (Intralase Corp., Irvine, CA), or cryolathe for the donor is that the donor cornea is smoother and gives better vision than can easily be obtained with a hand-cut lamellar donor. When I perform a penetrating transplant on a patient with previous herpes, I prescribe prednisone 60mg/day (his health permitting) beginning 1 or 2 days before surgery, continue this regimen for 2 weeks after surgery, and then taper the medication in order to avoid the flare-up and severe iritis occasionally associated with the grafts of herpes patients. I would have this patient begin Valtrex (Glaxosmithkline, Research Triangle Park, NC) 500mg t.i.d. before surgery and continue this dosing until decreasing the oral prednisone. I would then maintain him indefinitely on 500mg Valtrex q.d. If I use topical steroids (usually Pred Forte [Allergan, Inc.]) after surgery, I add Viroptic (Monarch Pharmaceuticals, Inc., Bristol,TN) drops with equal frequency to the corticosteroid drops. If I performed a graft for optical purposes in this case, I would minimize the distortion using a single running adjustable suture with suture bites that were not too long in the donor cornea. I would adjust the suture with a qualitative keratometer (a circle of lights adapted for the slit lamp) on the table and then again periodically in the postoperative period.
Considering the patient's long history of refractive surgery and a stromal-bed thickness of 290µm, I would try to avoid additional refractive surgery if possible.
Section editor Karl G. Stonecipher, MD, is Director of Refractive Surgery at Southeastern Eye Center in Greensboro, North Carolina. Dr. Stonecipher may be reached at (800) 632-0428; firstname.lastname@example.org.
D. Matthew Bushley, MD, is Clinical Associate, Cornea and Refractive Surgery Services, Duke University Eye Center in Durham, North Carolina. He states that he holds no financial interest in any product or company mentioned herein. Dr. Bushley may be reached at (919) 681-3568; email@example.com.
Elizabeth A. Davis, MD, FACS, is a partner at Minnesota Eye Consultants in Bloomington, and she is Adjunct Assistant Clinical Professor of Ophthalmology at the University of Minnesota in Minneapolis. She states that she holds no financial interest in the products or companies mentioned in her comments. Dr. Davis may be reached at (952) 885-2474; firstname.lastname@example.org.
Herbert E. Kaufman, MD, is Boyd Professor of Ophthalmology and Pharmacology and Microbiology at Louisiana State University Health Sciences Center, LSU Eye Center, New Orleans. He states that he holds no financial interest in any product or company mentioned herein. Dr. Kaufman may be reached at (504) 412-1200; email@example.com.
Terry Kim, MD, is Associate Professor of Ophthalmology, Cornea and Refractive Surgery Services, Duke University Eye Center in Durham, North Carolina. He states that he holds no financial interest in any product or company mentioned herein. Dr. Kim may be reached at (919) 681-3568; firstname.lastname@example.org.
Parag A. Majmudar, MD, is Associate Professor of Ophthalmology, Cornea Service, Rush University Medical Center in Chicago. He states that he holds no financial interest in any of the products or companies mentioned herein.
Dr. Majmudar may be reached at (847) 882-5900;
1. McLeod SD, Holsclaw D, Lee S. Refractive, topographic, and visual effects of flap amputation following laser in situ keratomileusis. Arch Ophthalmol. 2002;120:1213-1217.
2. Kaufman HE, Insler MS, Ibrahim-Elzembely HA, Kaufman SC. Human fibrin tissue adhesive for sutureless lamellar keratoplasty and scleral patch adhesion. A pilot study. Ophthalmology. 2003;110:2168-2172.