Intraoperative Microkeratome Complications in 47,094 Laser in situ Keratomileusis Surgeries

Flap Thickness and the Risk of Complications in Mechanical Microkeratome and Femtosecond Laser In Situ Keratomileusis: A Literature Review and Statistical Analysis

INTRODUCTION

A recent Cochrane review found no difference in visual acuity outcomes between femtosecond-assisted laser in situ keratomileusis (LASIK) and LASIK using mechanical microkeratomes (MMKs). This study compares the flap thickness and risk of complications related to flap creation using femtosecond lasers and MMKs.

METHODS

PubMed and the Web of Science are used to search the medical literature. An extensive search is performed to identify the flap thickness and complications of LASIK as reported up to 15 July 2021. The following keywords are used in various combinations: Corneal flap, femtosecond laser, laser in situ keratomileusis, laser-assisted in situ keratomileusis, LASIK, mechanical microkeratome.

RESULTS

After removing duplicates and irrelevant studies, 122 articles were included for review. Pooled differences for intended vs. postoperative flap thickness using MMKs and femtosecond laser were -4.07 μm (95% CI: -19.55, 3.24 μm) in studies on the MMK and 5.43 μm (95% CI: 2.30, 7.84 μm; p < 0.001), respectively. After removing the studies evaluating outcomes of the old generation Hansatome MMKs (which had a significantly greater variation of flap thickness), the pooled difference for newer MMKs was 4.97 μm (95% CI: 0.35, 9.58 μm; p < 0.001), but the results still favored the femtosecond laser. Uncommon and mild complications unique for the femtosecond LASIK are epithelial gas breakthrough, opaque bubble layer, transient light sensitivity syndrome, and rainbow glare. A single study reported a very low, but stastically different risk of postoperative flap slippage (0.033% for MMK LASIK, and 0.003% for femtosecond LASIK, respectively).

CONCLUSION

In both manual microkeratome and femtosecond LASIK, intra- and postoperative complications were uncommon. The evidence of the superiority of one technique in terms of complications over another cannot be indisputably stated.

Suction stability management in small incision lenticule extraction: incidence and outcomes of suction loss in 4000 consecutive procedures

PURPOSE

To report the incidence and outcomes of suction loss during small incision lenticule extraction (SMILE).

METHODS

The incidence of suction loss was measured over 4000 consecutive SMILE procedures and categorized by cause, the interface in which suction was lost and management (restart/continue SMILE, re-SMILE thinner cap, convert to laser in-situ keratomileusis [LASIK]). One-year outcomes were compared to the fellow eye where no suction loss occurred.

RESULTS

There were 20 cases of suction loss (0.50%): during the lenticule interface in seven eyes, lenticule side cut in one eye, cap interface in nine eyes and small incision for three eyes. Small incision lenticule extraction (SMILE) was continued in seven eyes, thinner cap SMILE in four eyes, LASIK in eight eyes, and the small incision was manually completed in one eye. Suction loss was caused by a Bell's reflex in 10 eyes, fixation light tracking in six eyes, patient anxiety in two eyes, a nociceptive reflex in one eye and false suction in one eye. There was no difference in results for suction loss and fellow eyes, respectively: uncorrected distance visual acuity was 20/20 or better in 100% in both groups, spherical equivalent was within ±0.50 D in 85% and 79%, one line loss of corrected distance visual acuity in 5% and 0%, and no eyes lost two lines.

CONCLUSION

Suction loss can be managed depending on the interface during which suction is lost. Treatment was completed on the same day in all instances. Visual and refractive outcomes were unaffected compared to the fellow eye in this series.

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis

PURPOSE

To determine factors associated with early flap misalignment following microkeratome-assisted laser in situ keratomileusis.

MATERIALS AND METHODS

This retrospective study included the right eyes of consecutive patients who underwent laser in situ keratomileusis procedure between 2005 and 2016 at Care-Vision Laser Centers, Tel-Aviv, Israel. Patients were divided into two groups according to whether or not they subsequently developed early flap misalignment.

RESULTS

A total of 14,582 eyes (mean age of patients: 32.4 ± 10.3 years) were included. Post-laser in situ keratomileusis early flap misalignment developed in 158 eyes (1.1%). Misalignment was more frequent during the spring (32.3% vs 22.8%, p = 0.003) and in a higher operating room temperature (23.34 ± 1.06 vs 22.98 ± 1.26, p < 0.001). In addition, in the misalignment group, there was a higher rate with the of use of the a Moria M2 microkeratome (rather than sub-Bowman's keratomileusis microkeratome) head (55.2% vs 40.5%, respectively, p < 0.001). In a multivariable analysis adjusted for surgeon and year of surgery, high operating room temperature (odds ratio = 1.22, p = 0.006), treatment zone of 9.0 mm (as opposed to smaller treatment zones, odds ratio = 1.54, p = 0.04), and springtime (odds ratio = 1.58, p = 0.02) were associated with flap misalignment. There was a significant difference in misalignment rates between surgeons (p = 0.02).

CONCLUSION

This study found that larger treatment zones, higher operating room temperature, operating during the spring, and the use of Moria M2 microkeratome were associated with increased flap misalignment rates. The association with operating room temperature and seasonal variation is of interest and merits further research.

Short-term complications of femtosecond laser-assisted laser in situ keratomileusis cuts: Review of 1210 consecutive cases

PURPOSE

To evaluate short-term complications after femtosecond laser cuts for laser in situ keratomileusis (LASIK).

SETTING

Department of Ophthalmology, Goethe University, Frankfurt, Germany.

DESIGN

Retrospective consecutive case series.

METHODS

Consecutive femtosecond laser cuts (1210 cuts in 624 patients) from LASIK performed with the Intralase FS60 between 2006 and 2014 were analyzed. The analysis looked at intraoperative and postoperative complications at 1 day, 1 week, and 1 month and factors with potential impact on the complication rate, such as ablation depth.

RESULTS

No irregular, incomplete, or thin flaps, buttonholes, gas breakthrough, or free caps were observed. Intraoperatively, incomplete side cuts were observed in 4 cases (0.3%). Three of the 4 occurred during the first year of femtosecond laser usage and were explained by a software problem. Epithelial defects, limbal bleeding, and decentered flaps without negative impact on outcome were observed in 45 (3.7%), 12 (1.0%), and 5 (0.4%) eyes, respectively, on the treatment date. Diffuse lamellar keratitis (DLK) stage 1 was observed in 69 (5.7%), 36 (3.0%), and 3 (0.2%) eyes at 1 day, 1 week, and 1 month, respectively, and DLK stage 2 in 20 (1.7%), 6 (0.5%), and 2 (0.2%) eyes, respectively. An increase in total ablation depth resulted in a higher incidence of microstriae (P < .01 at 1 day, 1 week, and 1 month). An increase in the optical zone resulted in a significantly higher incidence of epithelial ingrowth at 1 day and 1 week (P < .01).

CONCLUSION

No major cut-related complications were observed. The femtosecond laser is a safe option to create a flap in LASIK.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Histological analysis of a cornea following experimental femtosecond laser ablation

Corneal photorefractive surgery is currently performed by ablation of corneal stroma under the stromal flap. A stromal flap is created using a femtosecond (FS) laser or mechanical microkeratome, although the FS laser procedure is considered safer and more accurate. This review assesses and compares the use of FS laser versus mechanical microkeratome ablation for corneal stromal characteristics mainly examined by histology and cellular biological responses. Supporting data from our studies, using corneas of enucleated porcine eye globes, are included in this review. Histological analysis and experimental studies of cellular/tissue responses to FS laser irradiation should be further investigated, and the equipment used to perform these techniques should be improved.

Intraoperative and early postoperative flap-related complications of laser in situ keratomileusis using two types of Moria microkeratomes

The purpose of this study is to describe the incidence, management, and visual outcomes of intraoperative and early postoperative flap-related complications of laser in situ keratomileusis (LASIK) surgery using two types of Moria M2 microkeratomes. This retrospective analysis was performed on 806 primary LASIK cases. The intraoperative and early postoperative flap-related complications were identified and categorized according to type of Moria microkeratome. There were 52 intraoperative and early postoperative complications--one case of partial flap (0.124 %), one case of free flap (0.124 %), one case of small flap (0.124 %), 13 cases of epithelial defect (1.61 %), 12 cases of flap striae (1.49 %), 10 cases of diffuse lamellar keratitis (1.24 %), 10 cases of interface debris (1.24 %), three cases of epithelial ingrowth (0.37 %), and one case of microbial infection (0.124 %). The overall incidence of flap complications was 6.45 %. There were 27 right eye (6.73 %) and 25 left eye (6.17 %) complications. The incidence of complications with the Moria automated metallic head 130 microkeratome was 4.22 % and with the Moria single-use head 90 microkeratome was 2.23 %. We observed one culture-negative interface abscess which was cured with surgical cleaning and intensive medical treatment. The most common complication encountered was epithelial defects, followed by flap striae. Our study showed that LASIK with a microkeratome has a relatively low incidence of intraoperative and early postoperative flap complications. The authors have no financial interest in any of the issues contained in this article and have no proprietary interest in the development of marketing of or materials used in this study.

Intraoperative flap complications in laser in situ keratomileusis with two types of microkeratomes

PURPOSE

To determine the incidence and types of intraoperative flap complications in laser in situ keratomileusis (LASIK) encountered with the Hansatome microkeratome and the Moria microkeratome.

METHODS

In this retrospective case series, all patients with intraoperative flap complications who were treated between June 1999 and July 2008 at the Eye Consultants Center in Riyadh, Saudi Arabia, were identified and reviewed.

RESULTS

Of the 4352 subjects who underwent bilateral primary LASIK procedure, intraoperative microkeratome complications were detected in 89 eyes of 83 patients. The overall incidence of flap complications was 89/8704 (1.00%): incomplete flaps occurred in 53 eyes (0.60%), followed by buttonhole flaps in 17 eyes (0.19%), free complete flaps in 10 eyes (0.11%), free partial flaps in 6 eyes (0.07%), sluffed epithelium in 2 eyes (0.023%), and a splitted flap (vertical flap cut) in 1 eye (0.01%). The incidence rates of intraoperative flap complications with the Hansatome microkeratome and the Moria microkeratome were 1.21% (41/3378) and 0.90% (48/5326), respectively (P = 0.19). There was a statistically significant difference between the two microkeratomes with regard to the incidence of buttonhole flaps: 0.33% (11/3378) for the Hansatome microkeratome versus 0.11% (6/5326) for the Moria microkeratome (P = 0.04).

CONCLUSION

Generally, the incidence rates of intraoperative flap complications with the Hansatome microkeratome and the Moria microkeratome were similar. However, buttonhole flaps occurred more often with the Hansatome microkeratome (a type of microkeratome that produces larger flaps). The commonest complication encountered was the incomplete flap, followed by the buttonhole flap and free flap.

Laser in situ keratomileusis flap complications using mechanical microkeratome versus femtosecond laser: retrospective comparison

PURPOSE

To compare the incidence of flap complications after creation of laser in situ keratomileusis (LASIK) flaps using a zero-compression microkeratome or a femtosecond laser.

SETTING

John A. Moran Eye Center, Department of Ophthalmology, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Evidence-based manuscript.

METHODS

The flap complication rate was evaluated during the initial 18 months of experience using a zero-compression microkeratome (Hansatome) or a femtosecond laser (IntraLase FS60) for flap creation.

RESULTS

The flap complication rate was 14.2% in the microkeratome group and 15.2% in the femtosecond laser group (P = .5437). The intraoperative flap complication rate was 5.3% and 2.9%, respectively (P = .0111), and the postoperative flap complication rate, 8.9% and 12.3%, respectively (P = .0201). The most common intraoperative complication in the microkeratome group was major epithelial defect/sloughing; the rate (2.6%) was statistically significantly higher than in the femtosecond laser group (P = .0006). The most common postoperative complication in both groups was diffuse lamellar keratitis (DLK) (6.0%, microkeratome; 10.6%, femtosecond laser) (P = .0002).

CONCLUSION

Although the total complication rates between the 2 groups were similar, the microkeratome group had significantly more epithelial defects intraoperatively and the femtosecond laser group had significantly more DLK cases postoperatively.

Microkeratome complications

PURPOSE OF REVIEW

Complications from laser in-situ keratomileusis surgery are extremely rare. However, most of the complications involve construction of the corneal flap, which is fashioned using various mechanical or femtosecond laser microkeratomes. Here, we review and discuss complications of microkeratome flaps.

RECENT FINDINGS

Several large studies of microkeratome laser in-situ keratomileusis cases report a similar set of complications: partial or irregular flaps, buttonholes, and free flaps. Risk factors for these complications include increased age, preoperative hyperopia, and years of contact lens wear. Numerous animal and clinical studies have shown that the femtosecond platform produces flaps with greater stability with more consistent and accurate dimensions than the mechanical microkeratome. However, there is no significant difference in final visual outcome.

SUMMARY

The aim of this review is to report complications associated with mechanical microkeratomes in the construction of laser in-situ keratomileusis flaps and to see whether there is a significant disadvantage compared with the femtosecond laser.

Effect of Preoperative Keratometric Power on Intraoperative Complications in LASIK in 34,099 Eyes

PURPOSE

To evaluate the effect of preoperative keratometric power on the intraoperative complications in LASIK for myopia, hyperopia, and astigmatism.

METHODS

In this retrospective study, the records of 34,099 eyes of 17,388 patients who underwent LASIK for myopia, hyperopia, and astigmatism using the Moria LSK One manual microkeratome and the Bausch & Lomb Technolas 217 Z excimer laser were reviewed.

RESULTS

One thousand three hundred thirty-eight (3.92%) intraoperative microkeratome complications were identified in the total number of eyes: 571 (1.67%) free caps, 320 (0.93%) epithelial abrasions, 282 (0.82%) thin/irregular flaps, 126 (0.36%) incomplete flaps, and 39 (0.11%) flap buttonholes. When eyes were stratified according to preoperative keratometric power, eyes with flatter corneas usually had more free caps and incomplete flaps than eyes with steeper corneas (P < .05), whereas eyes with steeper corneas usually had more epithelial abrasions and thin/irregular flaps than eyes with flatter corneas (P < .05). The risk of free caps, incomplete flaps, and epithelial abrasions was greater when bigger keratome rings (H) were used than when smaller rings (-1) were used (P < .05). The incidence of buttonholes was independent of the preoperative keratometric power, keratome plate (100 or 130 microm), and keratome ring (-1, -2, or H).

CONCLUSIONS

No statistically significant relationship was found between preoperative keratometric power and incidence of flap buttonholes in this series. Eyes with flatter corneas tended to have more free caps and incomplete flaps, whereas eyes with steeper corneas tended to have more epithelial abrasions and thin/irregular flaps.

Repositioning of Free Cap Four Days After LASIK

PURPOSE

To report management and outcome of late repositioning of flap dislodgement after LASIK.

METHODS

A 27-year-old man underwent LASIK in the right eye for correction of myopia, which was complicated by free cap. The flap was repositioned, but dislodged 2 days later. The dislodged flap was stored in balanced salt solution for 48 hours and repositioned 4 days after initial surgery.

RESULTS

Postoperatively, the flap remained apposed, but diffuse lamellar keratitis and epithelial ingrowth developed, which was managed with topical steroids and topical mitomycin C. Stromal haze gradually decreased by 16 months postoperatively, resulting in best spectacle-corrected visual acuity of 20/20.

CONCLUSIONS

Flap dislodgement > 48 hours postoperatively can be repositioned with good visual outcome. The flap should be preserved in the event of such complication.

Efficacy of nonsimultaneous bilateral LASIK after nonsimultaneous bilateral penetrating keratoplasty

PURPOSE

To show if nonsimultaneous bilateral laser in situ keratomileusis (LASIK) is a safe and effective procedure for patients with bilateral penetrating keratoplasty (PKP).

METHODS

Five patients (10 eyes), with keratoconus, underwent PKP separately in each eye. After an average PKP follow-up of 45.8 months per eye, (range, 19-92 months), each eye underwent 1-stage LASIK using the Visx Star S3 laser to correct its residual refractive error. We used the cycloplegic refraction as the target for the LASIK surgery. Each patient had his or her eyes done separately 3 weeks apart.

RESULTS

Pre-LASIK myopia averaged -3.93 +/- 2.9 D, ranging from -10.00 to +0.75 D. Pre-LASIK astigmatism averaged -3.25 +/- 0.80 D, ranging from -1.75 to -4.50 D. Mean pre-LASIK keratometry was 45.4 +/- 2.6, ranging from 42.2 to 50.5. Uncorrected visual acuity pre-LASIK averaged 20/220, ranging from 20/60 to 20/400. Best-corrected spectacle visual acuity (BCSVA) pre-LASIK averaged 20/22, ranging from 20/20 to 20/30. Nine eyes had no complications. One eye had a flap buttonhole during LASIK, and surgery was aborted. No vision was lost in this eye. Mean follow-up after LASIK in the 9 eyes was 17 +/- 15.2 months, (range, 4-56 months). Mean post-LASIK ametropia in these 9 eyes was +0.25 +/- 0.45 D, ranging from -0.50 to +0.75 D. Average post-LASIK astigmatism was -0.33 +/- 0.38 D, ranging from 0 to -0.75 D. In the 9 treated eyes, uncorrected vision post-LASIK averaged 20/25, ranging from 20/20 to 20/30. BCSVA post-LASIK averaged 20/21, ranging from 20/20 to 20/25. No lines of visual acuity were lost in any of the eyes.

CONCLUSION

Young patients who have had bilateral PKP, with good postoperative vision and low levels of myopia, astigmatism, and minimal wound override, are good candidates for bilateral nonsimultaneous LASIK. Further studies can now be done on the performance of bilateral simultaneous LASIK in patients who have had corneal transplant surgery in both of their eyes.

Artemis very high-frequency digital ultrasound-guided repositioning of a free cap after laser in situ keratomileusis

We present a patient in whom a symmetrically round free cap occurred during laser in situ keratomileusis (LASIK), and flap repositioning was performed without laser ablation. A loss of 3 lines of best spectacle-corrected visual acuity (BSCVA), monocular diplopia, and topographic irregular astigmatism confirmed that the free cap orientation was incorrect. Two subsequent free cap rotations based on refraction failed to realign the free cap into its original position. Artemis 3-dimensional very high-frequency digital ultrasound analysis found the thickness profiles of the free cap and bed to be irregular and mismatched. The rotation required for anatomic realignment was determined by digitally generating a "lock and key" superimposition of the free cap and stromal bed thickness profiles. After Artemis-guided free cap rotation, the eye regained preoperative BSCVA and symmetrical corneal topography with a +0.50 diopter change in spherical equivalent.

Corneal multiphoton microscopy and intratissue optical nanosurgery by nanojoule femtosecond near-infrared pulsed lasers

Multiphoton microscopy including multiphoton autofluorescence imaging (MAI) and second-harmonic generation (SHG) is being used as a novel diagnostic tool to perform tissue nonlinear optical tomography with submicron resolution. The three-dimensional corneal ultrastructure of whole depth has been viewed without any staining or mechanical slicing. Compared with photodisruptive surgical effects occurring at TW/cm2 light intensity, multiphoton imaging can be induced at MW-GW/ cm2 photon intensity. The intratissue surgical effect including nanojoule (nJ) femtosecond laser ablation and flap generation was induced through multiphoton nonlinear absorption at a wavelength of 800 nm and ascertained by the histological outcomes. More interesting, the multiphoton microscopy based on nonlinear absorption of femtosecond laser pulses at the wavelength of 715-930 nm emitted from solid-state Ti:sapphire system is acting as a precise non-invasive monitoring tool to determine the interest of region, to visualize and verify the outcomes in in vivo intrastromal laser nanosurgery. Overall, these data suggest that multiphoton microscopy is a highly sensitive and promising technique for studying the morphometric and biomechanical properties of biological tissues and that the nJ ultrashort Lasers can be used as a ultra-precise nanoscalpel for performing intratissue surgery.

Laser eye surgery for refractive errors

Several laser and non-laser refractive surgical procedures have been used to modify the shape of the cornea and correct myopia, hyperopia, astigmatism, and presbyopia. Introduction of the excimer laser to reshape the cornea has resulted in remarkable developments in the correction of these refractive errors. Combined with other advanced ophthalmological instruments, laser refractive eye surgery has resulted in a substantial rise in the safety, efficacy, and predictability of surgical outcomes. Despite these advances, certain limitations and complications persist. In this review, we describe the history, preoperative assessment, surgical techniques, outcomes, and complications of laser refractive surgery.

Photorefractive keratectomy (PRK) versus laser-assisted in-situ keratomileusis (LASIK) for myopia

BACKGROUND

Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK).

OBJECTIVES

The aim of this review was to compare the effectiveness and safety of PRK and LASIK for correction of myopia.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2005, Issue 3), MEDLINE (1966 to September 2005), EMBASE (1980 to September 2005) and LILACs (1982 to 3 November 2005). We also searched the reference lists of the studies and the Science Citation Index.

SELECTION CRITERIA

We included randomised controlled trials comparing PRK and LASIK for correction of any degree of myopia. We also included data on adverse events from prospective multicentre consecutive case series in the Food and Drugs Administration (FDA) trials database (http//www.fda.gov/cdrh/LASIK/lasers.htm).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Data were summarised using odds ratio and mean difference. Odds ratios were combined using a random-effects model after testing for heterogeneity.

MAIN RESULTS

This review included six randomised controlled trials involving a total of 417 eyes, of which 201 were treated with PRK and 216 with LASIK. We found that although LASIK gives a faster visual recovery than PRK, the effectiveness of these two procedures is comparable. We found some evidence that LASIK may be less likely than PRK to result in loss of best spectacle-corrected visual acuity.

AUTHORS' CONCLUSIONS

LASIK gives a faster visual recovery than PRK but the effectiveness of these two procedures is comparable. Further trials using contemporary techniques are required to determine whether LASIK and PRK are equally safe.

Laser in situ keratomileusis in patients with diabetes

PURPOSE

To study the outcomes of laser in situ keratomileusis (LASIK) in patients with well-controlled diabetes mellitus.

SETTING

Gimbel Eye Centres, Calgary and Edmonton, Canada.

METHODS

The charts of all patients with diabetes who had LASIK surgery at the Gimbel Eye Centres were reviewed retrospectively. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), final refraction, and complications were assessed.

RESULTS

Twenty-four patients (16 men and 8 women) were identified. Mean patient age was 42 years (range 24 to 57 years). Seventeen patients had diabetes type II, and 7 had diabetes type I. Mean preoperative spherical equivalent (SE) was -4.88 +/- 2.13 diopters (D) (range +1.625 to -9.00 D). Median follow-up was 6 months (range 4 to 44 months). No eye lost BSCVA. Twenty-nine eyes (63%) achieved UCVA 20/25 or better, and 31 eyes (67%) were within +/-0.5 D of the intended refraction after the first LASIK surgery. Retreatment was required in 13 eyes (28.3%) because initial surgery was not adequate to correct the refractive error. At the last follow-up visit, 40 eyes (87%) achieved UCVA of 20/25 or better and 43 eyes (93.5%) were within +/-0.5 D of the intended refraction. Three eyes (6.5%) developed an epithelial defect after surgery, and secondary epithelial ingrowth developed in 2 of these eyes. No advancement of diabetic retinopathy was noticed in any eye at the end of the follow-up period.

CONCLUSIONS

Laser in situ keratomileusis surgery was safely performed in patients with well-controlled diabetes. Enhancement may often be required for optimal correction.

Complications and visual outcome of LASIK performed by anterior segment fellows vs experienced faculty supervisors

PURPOSE

To determine the complication rates and visual outcome of laser-assisted in situ keratomileusis (LASIK) that is performed by anterior segment fellows and to compare their results with the results of their experienced faculty supervisors.

DESIGN

A single-center, retrospective, interventional, nonrandomized, comparative case series.

METHODS

Chart review of the initial 50 LASIK procedures that were performed by each of 10 anterior segment fellows and the first 50 inclusion criteria-matched, contemporaneously performed cases of four faculty members at the King Khaled Eye Specialist Hospital between March and December 2003.

RESULTS

There were no statistically significant differences between fellow and faculty cases with respect to complication rates and final visual outcomes. The fellows were significantly more likely to experience microkeratome-related flap complications during their first 25 cases, compared with their second 25 cases (4.8% vs 1.2%; P = .03). Fellows were significantly more likely to perform enhancements (8.0% vs 2.0%; P = .0002), after which the eyes in their group were more likely to be within 1 diopter of the intended refractive target than those in the faculty group (96.0% vs 91.0%; P = .01). Although not statistically significant, eyes in the fellow group were four-fold (2.0% vs 0.5%) more likely to lose two or more lines of best spectacle corrected visual acuity than those in the faculty group.

CONCLUSION

To minimize the adverse impact of complications during the learning curve of novice LASIK surgeons, the introduction of this procedure in a well-structured, supervised setting (such as a subspecialty fellowship training program) is recommended.

Incidence of Complications During Flap Creation in LASIK Using the NIDEK MK-2000 Microkeratome in 26,600 Cases

PURPOSE

To evaluate the incidence of intraoperative complications using the NIDEK MK-2000 microkeratome during flap creation in LASIK.

METHODS

The incidence of intraoperative flap complications during LASIK using the NIDEK MK-2000 microkeratome was retrospectively studied in 26,600 procedures performed in 5 outpatient excimer laser surgery centers.

RESULTS

A total of 65 (0.244%) complications were identified: 23 (0.086%) eyes had free caps, 13 (0.049%) eyes had an incomplete pass, 13 (0.049%) eyes had an epithelial defect, 11 (0.041%) eyes had buttonhole, and 5 (0.019%) eyes had irregular flap. The remaining 26,535 (99.756%) eyes had uneventful flap creation.

CONCLUSIONS

Use of the NIDEK MK-2000 microkeratome resulted in a low incidence of intraoperative complications, making it a safe and reliable device for creating flaps during LASIK.

Improved Safety in Contemporary LASIK

PURPOSE

To examine the risk of serious visual loss in contemporary LASIK.

DESIGN

Retrospective, noncomparative, consecutive case series combined with a structured literature review and comparison with historical controls.

PARTICIPANTS

One thousand consecutive cases of LASIK performed from January 2000 to January 2004 by 1 surgeon. One thousand nine hundred eighty-two cases with 6-month review data in postmillennial Food and Drug Administration (FDA) trials of LASIK for myopia and astigmatism and 5203 patients with 6 month review data in similar premillennial FDA trials.

METHODS

LASIK was performed with the Hansatome microkeratome and a VISX Star (S2, S3, or S4) laser. There were 899 myopic treatments (spherical equivalent < or =-10.5 diopters [D]; average -4.2 D; standard deviations [SD] D = 1.9 D; astigmatism < or =4.75 D), 87 hyperopic treatments (spherical equivalent < or =+4.25 D; average +2.4 D; SD = 0.9 D; astigmatism < or =3.5 D), and 14 treatments for mixed astigmatism (< or =4.5 D). Outcome data were obtained from a review of case notes and compared with historical data from FDA trials.

MAIN OUTCOME MEASURES

Best-spectacle corrected visual acuity (BSCVA) preoperatively and at final review was compared in our case series with reference to the United Kingdom driving standard (BSCVA> or =20/30). Subsidiary outcome measures included duration of follow-up, intraoperative, and postoperative complication rates. Six-month postoperative data on standard safety criteria (numbers of patients losing > or =2 lines BSCVA, BSCVA <20/40, and final BSCVA <20/25 for patients with preoperative BSCVA > or =20/20) were examined in FDA trials.

RESULTS

In our clinical series, no case with a preoperative BSCVA of 20/20 or better had a final BSCVA of <20/30 at final review (97.5% confidence interval [CI], 0%-0.37%); 4 eyes had a BSCVA <20/25 (0.41%; 95%CI, 0.11%-1.02%). The median interval between surgery and final review was 2 months (range, 1-45 months). In FDA studies recruiting pre-2000, 1.4% of patients lost > or =2 lines of BSCVA versus 0.6% in postmillennial studies (P = 0.005); 0.45% of patients in premillennial studies lost BSCVA to <20/40 compared with no patients in postmillennial studies (P = 0.001); and 1.68% of patients in premillennial studies with a preoperative BSCVA > or =20/20 had a postoperative BSCVA <20/25 compared with 0.16% in postmillennial studies (P< or =0.001).

CONCLUSIONS

Compared with premillennial results, the risk of visual loss is significantly reduced in contemporary LASIK.