CLINICAL COMMUNICATIONS: Clinical Cases
Laser in situ keratomileusis (LASIK) is the most commonly performed refractive surgery worldwide.1 With an ongoing improvement in technology, an increase in the number of LASIK procedures can be expected in the coming years. This would directly affect the potential pool of donor corneas in the distant future.2 There have been isolated reports in the past decade where donor corneas that have been subjected to refractive surgery were transplanted accidently into recipient eyes.3,4 In the past decade, lamellar corneal transplantation is being increasingly used to treat patients with anterior as well as posterior corneal pathologies.5 Although donor corneas with a history of refractive surgery are deemed suitable for posterior lamellar keratoplasty, the same cannot be entirely concluded for anterior lamellar keratoplasty.6 We present a case that underwent deep anterior lamellar keratoplasty (DALK) using a cornea with a previous history of LASIK. The LASIK flap was discovered on postoperative follow-up.
An 18-year-old male patient with bilateral keratoconus was referred to the Cornea Clinic of our hospital with the chief complaint of gradual diminution of vision in both eyes for a few years. The best-corrected visual acuity was counting figures OD and 6/18 OS at the time of presentation. Slit-lamp examination of both eyes showed corneal thinning with ectasia along with apical corneal scarring, Vogt striae, and Fleischer ring. The central corneal thickness measured with ultrasonic pachymetry was 220 µm OD and 460 µm OS. The corneal keratometry was 69.2/77.8 D OD and 41.8/61.8 D OS. The patient failed a hard contact lens trial because of intolerance to contact lenses. Consequently, the patient was consented for a deep anterior lamellar keratoplasty in his right eye.
Surgery was performed under general anesthesia using the diamond knife–assisted deep anterior lamellar keratoplasty.7 The center of the host cornea was marked first, followed by a 7.5-mm circular mark which was made with a disposable trephine blade (Madhu Instruments, New Delhi, India) whose edges had been stained with gentian violet. Intraoperative ultrasonic pachymetry (Sonomed, Micropach, Model 200P+) was performed on this corneal mark between 11 and 1 o’clock position. A diamond knife set at a depth 30 μm less than that of intraoperative pachymetry reading was used to make an incision of 2 mm at 11-12 o’clock position. Medium curved fine-blade scissors (Cindy Scissors; Bausch and Lomb, St. Louis, MO) were then used to extend the incision on either side circumferentially for 360 degrees. An open centripetal lamellar dissection was carried out using lamellar dissectors. The central stromal disc was then excised leaving a thin residual stromal bed.
The donor corneoscleral button was placed endothelial side up on a wet Teflon block.
The donor button was punched from the endothelial side and was oversized by 0.25 mm. The Descemet membrane (DM) of the donor lenticule was stripped after staining with 0.1 mL of 0.06% Trypan Blue (Visiblue; Shah & Shah, India). The donor lenticule was placed on the host bed and was sutured using 10-0 monofilament nylon sutures. Postoperatively, the patient received prednisolone acetate 1% eye drops four times a day, moxifloxacin hydrochloride 0.5% eye drops three times a day, and preservative free artificial tears four times a day.
One week postoperatively, the uncorrected visual acuity was 6/24 and the keratometry readings were 36.4/48.6 D in the operated eye. Slit-lamp examination showed a clear graft and a quiet anterior chamber. In addition to the graft-host interface in the deep corneal stroma, an additional interface was observed in the anterior corneal stroma (Fig. 1). An anterior segment optical coherence tomography (ASOCT; Visante) was performed on the left eye. The central corneal thickness was 500 µm and the residual stromal thickness was 62 µm. The ASOCT showed two distinct interfaces, one in the deep corneal stroma close to the DM and another interface in the anterior corneal stroma, 200 µm below the surface of the cornea (Fig. 2). Subsequently, the records of the donor were checked again from the Eye Bank. The donor was a 57-year-old male patient who had died of a road traffic accident. There was no record of any history of refractive surgery in the past.
The patient was informed about the presence of a LASIK flap on his cornea. Because the patient is asymptomatic, a decision was taken to observe instead of exchanging the graft.
This is the first case report of post-LASIK cornea being accidentally used for a DALK. Previous studies have recommended the potential use of corneal topography and pachymetry for screening of Eye Bank corneas for refractive surgery.8–10 However, it is not desirable to screen all corneas using these methods. ASOCT has been also been used to identify the characteristic features of flap interface of post-LASIK donor corneas.11–14 Lin et al. showed that ASOCT is able to provide thickness and topography maps of donor corneas through the sterile eye bank containers.14 The authors believe that the anterior surface refractive power was the best predictor of LASIK compared to non-LASIK donor corneas. Corneal thickness mapping on the other hand was not found to be a sufficient test, possibly resulting from variable swelling during corneal preservation. However, ASOCT could not detect the flap interface in these corneas. Another case study recommends performing ASOCT in donor corneas stored in organ culture between 9 and 12 days postmortem.11 Priglinger et al. created LASIK flaps on donor eye corneas before storing them in organ culture medium.12 The authors performed ASOCT between 1 and 6 months of storage and concluded that it was possible to detect LASIK interface in the donor corneas. In the light of these findings, there are no guidelines from the Eye Bank Association of America for screening of refractive surgery in donor corneas.15
The use of post-LASIK donor corneas may be associated with intraoperative problems related to the use of suction trephine and suturing. Some surgeons have experienced a split of the donor corneal lamellae intraoperatively during corneal transplantation.2 Postoperatively, a wide variation can be expected in refraction and keratometry readings depending on whether the donor cornea was subjected to a myopic or a hyperopic LASIK. There may be potential problems associated with wound healing. Most importantly, these eyes are at a potentially high risk for blunt trauma–related damage because of the presence of a LASIK flap on the surface of the eye. Long-term follow-up of these cases is essential to see if it is safe to leave these corneas sutured on instead of replacement with another healthy cornea.
A careful history of any previous ocular surgery should undoubtedly be one of the most useful ways to know if the donor had undergone any refractive surgery. Wolf et al. have reported a case where a mention of a history of laser treatment prompted the authors to look for a LASIK flap in donor cornea on optical coherence tomography.11 This may, however, be missed by the eye bank team as well as the relatives of the deceased. Furthermore, a normal sit-lamp examination and endothelial cell counts cannot rule out previous refractive surgery. It was definitely easier to spot radial keratotomy cuts on the surface of donor corneas in the past as compared to now when most cases undergo advanced surface ablation or a thin-flap LASIK. The difference in corneal thickness measurements in central and peripheral cornea may provide some evidence in support of a previous refractive surgery procedure. ASOCT seems to a promising technique as evidenced by the past and recent literature.13 It would be prudent to improve the techniques of ultra-high-resolution ASOCT so that the LASIK flap interface can be detected even with variable storage media and storage times that are being used in different eye banks around the world. This would potentially cost a lot more in terms of money and manpower. Also, if such a practice has to be implemented, the eye bank technicians would need training from clinicians to use the ASOCT for donor screening.
In an event of accidental transplantation of post-LASIK donor cornea, the patient should be informed immediately. The eye bank personnel should be consulted so that transplantation of the fellow eye cornea could be stopped in time or the recipient of the fellow eye cornea could be traced. If a graft exchange has to be planned in this situation, it is easier in a DALK compared to a full-thickness penetrating keratoplasty. In our case, the graft was clear and the visual acuity was good. The patient opted for observation instead of a repeat corneal transplantation. A long-term follow-up would be needed to observe any changes in the morphology of the LASIK flap in our patient.
Our case report highlights the accidental transplantation of a post-LASIK donor cornea during a DALK. Although rarely reported, it is possible that such occurrences are missed in the postoperative follow-up visits. With the increasing popularity of laser refractive surgery, clinicians have to be more careful when transplanting corneas especially from young donors. Eye bank donor screening questionnaire should specifically list a history of laser refractive surgery. Donor screening procedures can include a routine ASOCT with the help of ocular imaging experts in cases with high index of suspicion of previous refractive surgery.
Rasik B. Vajpayee
Centre for Eye Research Australia
University of Melbourne
32 Gisborne Street
East Melbourne, Victoria 3002
The authors declare no proprietary/financial interests, financial disclosures, or conflict of interest in any products/techniques mentioned in the text.
Received October 8, 2013; accepted October 21, 2013.
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Keywords:© 2014 American Academy of Optometry
deep anterior lamellar keratoplasty; LASIK; flap; donor cornea; complication