From the Istanbul Eye Hospital (HZB); and Sisli Etfal Education and Research Hospital (GG), Eye Clinic, Istanbul, Turkey.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to H. Zeki Büyükyildiz MD, PhD, Istanbul Eye Hospital Neyire Neyir sk. No. 3 Bahçelievler Istanbul 34590, Turkey.
Laser in situ keratomileusis (LASIK) has become the most common refractive surgery technique for correction of refractive errors.1–3 Some intraoperative and postoperative complications can occur in LASIK surgery. The most common intraoperative complications are associated with cutting of the corneal flap with the keratome.4 To our knowledge, a LASIK complication due to excimer laser firing failure has not been described previously. In this paper, we present such a case and its management.
A 30-year-old man was scheduled for LASIK surgery. Preoperatively his uncorrected visual acuities (UCVA) were 20/60 and 20/50 with a manifest refraction of −2.50 × 180 and −1.75 × 180 in the right and left eye, respectively. The best-corrected visual acuities (BCVA) were 20/20 in both eyes. The cycloplegic refraction and the treatment profile were −2.50 ×180 for the right eye and +0.50 −1.75 × 180 for the left eye. Central corneal thicknesses (CCT) measured by Orbscan® (Bausch & Lomb, Rochester, NY) pachymetry were 507 and 515 μm in the right and left eye, respectively.
The surgery was performed by HZB using a Hansatome® Excellus microkeratome (Bausch & Lomb, Rochester, NY). The corneal flap was superiorly hinged. The flap depth was 160 μm, the flap size 9.5 mm, and the optical zone 6.0 mm. Both eyes were treated with a conventional laser ablation profile and the depth of the excimer laser ablations were 47 μm in the right eye and 37 μm in the left eye.
Surgery on the right eye was completed uneventfully. During surgery of the left eye a regular corneal flap was cut and excimer laser treatment was initiated with the aid of the eye tracker. However, at 34% completion the excimer laser (Technolas® 217z Bausch & Lomb, Rochester, NY) suddenly stopped firing for no apparent reason. The flap was covered on the cornea, and the patient was sent to the waiting room. The laser technician was called and he resolved the problem within 20 mins. He stated that the problem was called a zyboot error, which happens due to fluctuation in the pneumatic pressure that is critical for the zyrobot card system in the Technolas® 217z. Then, the same preoperative treatment profile was loaded into the instrument, and 34% of the laser treatment was applied to a piece of paper. The patient was brought to the operating room, the corneal flap reopened with a cannula, and the remaining (66%) laser treatment was applied but without using the eye tracker. The surgery was completed without any further problems.
The patient was examined the first day, the first week, and the first, fourth, and sixth months postoperatively. On the first postoperative day the left cornea was clear and the UCVA was 20/20. At the end of the first week the UCVA was 20/16 with no refractive error in the left eye. The UCVA and the refractive error remained unchanged during the 6-month follow-up period. The CCT, which was 515 μm preoperatively, measured 438 μm at the first day postoperatively and 466 μm at 6 months (Figure).
Figure. The Left Corneal Topographic and Pachymetric Measurements (A) Preoperatively, (B) at the Next Day, and (C) at 6 Months Postoperatively, Respectively.
Although LASIK has become a popular technique in refractive surgery, intraoperative, and postoperative complications can occur. Intraoperative complications include epithelial injury, keratome failure, suction loss, and flap complications. Some complications such as an incomplete flap may prevent the surgery from being finished. In our case, the LASIK surgery had to be abandoned due to excimer laser firing failure. In such challenging circumstances it is important to remain calm and not panic. If the failure is not due to an electrical power problem, then the Technolas excimer laser instrument continues to display how much of the treatment was completed. In the present case, this value (34%) was recorded and the treatment was completed after the technician fixed the laser problem. Re-initiating treatment simply required uploading the refractive values of the patient to the machine and applying the initial 34% treatment to a blank piece of paper and the remaining 66% to the patient’s left eye.
If the laser firing problem is not likely be resolved within the operating session time, then in our opinion the patient should be re-treated no sooner than 1 month after the aborted treatment. The refraction of the eye must be stabilized after the initial incomplete treatment.
We found no reports in the literature of complications related to laser firing failure during LASIK. After consulting with our colleagues, we learned that some of them had experienced similar complications in the past. In 2002, Ofluoglu had to stop surgery in one case due to laser firing failure after having completed treatment of 3 of 4 zones. After the laser instrument was repaired, Ofluoglu applied the fourth zone treatment to the eye after delivering the initial three zones’ radiation onto a blank piece of paper. He related there were no postoperative refractive complications (A. Ofluoglu, Deutsche Krankenhaus Eye Clinic, Istanbul; personal communication).
Cetin experienced a similar complication twice. In 2000, he had to stop LASIK surgery after he applied 2,396 pulses with a Technolas 217z because its screen became ‘frozen.’ One day later, after entering the same refractive values into the machine, he applied the first 2,396 pulses to a blank piece of paper and the remaining treatment to the eye. He added that there were no problems in the postoperative follow-ups. In a second case, Cetin again had to stop the surgery after completing 12% of treatment with an Allegretto wave Eye-Q (Wavelight AG, Erlangen, Germany). After the machine was fixed, he applied the first 12% of treatment to a blank piece of paper and completed the treatment without any postoperative complications. He added that the patient’s UCVA was 20/20 postoperatively (T. Cetin, Sisli Government Hospital Eye Clinic, Istanbul; personal communication).
Ayoğlu, also, encountered a similar problem with a Technolas Kerakor 216 (Bausch & Lomb, Rochester, NY, USA) excimer laser instrument after completing 40% of the treatment. She took the patient to another clinic with the same laser machine and completed the treatment in a similar manner without any refractive problems postoperatively (B. Ayoğlu, Istanbul Surgery Hospital Eye Center, Istanbul; personal communication).
Azizagaoglu said that he had to stop LASIK surgery after completing 32% of the treatment due to a Zywave card holder error in the Technolas 217 instrument. He completed the treatment without any further problems after firing the first 32% onto a blank sheet of paper. He related that he had had another experience with a Visx S4 IR instrument (AMO, Santa Ana, CA) due to a fluoride sensor warning. After the instrument was fixed he completed the surgery without any further problems. An advantage of the Visx S4 is that it stores the treatment parameters and continues the surgery from where it stopped if the treatment was not completed, even if the machine is turned-off. He advised to cover the stromal flap to prevent uneven drying of the stromal bed if the waiting period is likely to be long (H. Azizağaoğlu, Bayrampasa Eye Hospital, Istanbul; personal communication).
We described an unusual intraoperative complication during excimer laser surgery. Although many flap-or keratome-related intraoperative complications have been reported in LASIK surgery, to our knowledge this is the first case of a complication due to excimer laser firing failure. If the laser problem can be resolved expeditiously, then the remaining laser treatment can be applied in the same operating session as a practical solution. We suggest that a crucial point is to complete the surgery with same type of instrument.
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