Managing Epithelial Ingrowth
The patient in this case was a 43-year-old information technology consultant with an original refractive error of -3.00 -1.50 X 90º in each eye. Best spectacle-corrected acuity (BSCA) was 20/20 in each eye, and a complete ophthalmologic examination was normal apart from myopic astigmatism.
The patient underwent uncomplicated, bilateral LASIK surgery (the surgeon employed a 160-µm cap). This was a patient of mine from several years ago, on whom I used the Automated Corneal Chaper™ (ACS) (Bausch & Lomb Surgical, Claremont, CA). The plate depth of 160 µm could have meant that a cap of anywhere as low as 90 µm may have been produced. At the time of surgery, there was no suggestion that the cap was unusually thin, or that the procedure would prove problematic. Initially, the patient did very well with unaided 20/20 acuity in each eye, with no measurable refractive error. At 4 weeks, the patient had a modest degree of regression to -1.00 in each eye. The patient was corrected to 20/20 in each eye and at 6 months, when documented stability was noted, an enhancement was suggested.
Enhancements
The enhancements were scheduled to be performed 1 week apart. At that stage, the surgeon's technique was to recut rather than lift, so a left enhancement was performed, again using an ACS with a plate depth of 160 µm. A new flap was cut without difficulty, an enhancement performed, and 1 week later, the patient was happy with unaided 20/20 acuity and no refractive error. At this point, a right enhancement was performed. Again, the ACS device was used to cut a cap using a plate depth of 160 µm. A free cap was created, and the cap was noted to be thin and smaller than 8 mm in diameter. The epithelium was intact, so the enhancement ablation was performed and the cap repositioned.
Complications Abound
Within 1 week, significant epithelial ingrowth was noted in the patient's right eye, causing irregular astigmatism and a reduction in BSCA. The epithelial ingrowth encroached toward the visual axis, so at 2 weeks following the recut enhancement, the corneal cap was lifted with a small edge left as a pseudohinge, and the epithelial ingrowth was removed from both the stromal bed and undersurface of the cap. The cap was repositioned and a bandage contact lens was applied. Despite what appeared to be an initial surgical success, a recurrence of epithelial ingrowth occurred. Again, this was significant, with a reduction in BSCA and epithelial cells evident in the visual axis.
Cap Removal
At 1 month following the original enhancement procedure, the patient returned for removal of epithelial ingrowth. At this stage, the cap was completely removed. The stromal bed and the underside of the cap were manually cleared of epithelial cells. It was noted that the cap was very thin, and a light PTK was applied to both the stromal bed and the undersurface of the cap in an attempt to destroy any remaining epithelial nests. The cap was then repositioned and sutured with eight 10–0 nylon interrupted sutures.
In the first few weeks after the procedure, the appearance of the cap under the slit lamp was extremely good. The sutures were intact and buried. The cap, although thin, was clear and free of recurrence of epithelial ingrowth. The patient's vision, however, was limited to best-corrected 20/100 due to central regular astigmatism, but it was envisaged that over the next 1 to 2 months, the sutures would be removed and the best-corrected vision would improve.
Severe Vision Loss
Prior to suture removal, however, the patient attended urgently with severe loss of vision in the left eye to best-corrected vision of count fingers. At this stage, the patient had had bilateral LASIK, bilateral enhancements, and two further procedures on the right eye for epithelial ingrowth, and the BSCA in the right eye was 20/100. The patient had been maintaining unaided 20/20 acuity in the left eye, which was now reduced to count fingers due to a retinal detachment. Retinal detachment surgery was performed, which was anatomically successful. Three weeks later, the detachment recurred, and further retinal detachment surgery was performed. For a considerable period of time, the patient was both functionally and almost legally blind.
Suture Removal
As the vision in the left eye (which had retinal detachment) slowly improved, the vision in the right eye, which had had the epithelial ingrowth, deteriorated because of a further recurrence of severe epithelial ingrowth. The decision was made at that stage to take out the sutures and remove the corneal cap entirely to allow re-epithelialization of the corneal surface. The corneal cap was removed and a bandage contact lens was applied with topical antibiotics (ciprofloxacin). The bandage contact lens was removed at day 4, and the corneal epithelium was intact. No topical corticosteroids were used. The patient continued to steadily improve.
One year following these events, the patient's vision is remarkably good with unaided acuity of 20/50 in each eye. With a relatively small hyperopic astigmatism correction at +1.50 -1.25 X 70º, the patient achieves 20/20- acuity in the right eye, and with a small myopic correction 20/25 in the left. The right cornea where the multiple corneal surgeries were performed and the cap has been removed, remains perfectly clear with no trace of haze.
Lessons To Be LearnedThis case illustrates an important lesson. I think that sometimes when the situation seems exceedingly bleak, both for the patient and surgeon, it sometimes, given the right combination of good management and a little luck, turns out for the best.
Recut or Relift?
Was it right to recut as opposed to relift when the enhancement was performed at 6 months? We have previously published studies1 to suggest that there is no real difference in efficacy or morbidity between recutting and relifting when performing enhancements. The technique of lifting a cap for enhancement is now so refined and successful (and the perceived problem of an increased rate of epithelial ingrowth so rare) that lifting is preferred to perform enhancements in almost all cases, certainly at 6 months and even out to 2 years or more. The recutting in this circumstance, given that the cornea was already slightly flat, may have contributed to the thin, free cap, and it is at least theoretically possible that the reapplication of the suction ring may have played some role in the development of the retinal detachment. It is possible that the whole sequence of events in the right eye would have been avoided if a modern epitheliorhexis lifting technique had been performed, rather than recutting.
Flap Quality
The creation of the free flap itself would not have been a considerable problem. If the flap is of good quality, ablation can still be performed and the flap repositioned without undue difficulty. It becomes more complex when the free flap is also thin and possibly irregular, which makes it harder to reposition. It means more manipulation of the flap, and the possibility of inducing epithelial defects with the secondary problem of epithelial ingrowth.
Combine Modalities
Managing epithelial ingrowth is a chapter in itself.2 When clinically significant, it needs to be removed, using at least a manual approach for the undersurface of the cap and bed, as the epithelium is rarely just on one surface. More difficult recurrences may require other modalities, such as a combination of PTK and dilute (10%) alcohol. Edge apposition, which is also crucial, was complicated in this particular case because of the thin irregular flap and the need to suture it. It is possible that the sutures themselves contributed to the recurrence of ingrowth by allowing a track to develop. These days, suturing is rarely required to deal with flap difficulties, but if required, an 11–0 nylon is preferred to 10–0, and early suture removal within the first 3 to 6 weeks is almost always possible.
A Positive Outcome
Lastly, the patient's outcome was quite successful despite the cap removal. There is no doubt that sometimes cap removal will lead to prolonged visual recovery with scarring of the corneal surface and a loss of BCVA, and not uncommonly, secondary flattening with hyperopic astigmatism (both regular and irregular). In this case, we were fortunate. After flap removal, the cornea healed promptly with no loss of corneal clarity and only very minimal induced hyperopic astigmatism. I think one of the factors contributing to this fortuitous result was that the cap itself was thin, and only a small ablation had been performed. Patients who have undergone cap removal that has subsequently led to significant scarring have tended to have caps of normal thickness, and have had larger ablations performed. This is not the whole answer as some corneas will tend to progressively scar even under the best circumstances, but it is worth keeping in mind if you are faced with the dilemma of ultimate cap removal.
1. Domniz Y, Comaish I, Lawless M, et al: Re-cutting the cornea versus lifting the flap; a comparison of two enhancement techniques following LASIK. J Refract Surg 17:505-510, 2001
2. Domniz Y, Comaish I, Lawless M, et al: Epithelial ingrowth: Causes, prevention and treatment of five different cases. J Cataract Refract Surg (in press)
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