Flap complications associated with lamellar refractive surgery

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.

Corneal intrastromal tissue modeling with the femtosecond laser

PURPOSE

To determine whether central corneal thinning and flattening can be achieved by intrastromal photodisruption using a femtosecond (fs) laser.

SETTING

Institute of Clinical Neuroanatomy, Goethe-University, Frankfurt am Main, Germany.

METHODS

Fourteen horizontal, parallel intrastromal cuts were performed on rabbit eyes using a fs laser. Full-grown rabbits (group 1; ten eyes) received bilateral treatment. Growing rabbits (group 2) received unilateral treatment (four eyes). Slit-lamp examination, pachymetry, and keratometry were performed on day 9, 31 and 86 (group 1) or on day 12, 29, 69, 176 and 318 (group 2) after surgery.

RESULTS

Nine days after treatment, corneal swelling was present and a slight increase of mean corneal thickness (group 1: +4.40 ± 5.56 μm) as well as a steeper mean corneal curvature (group 1: -0.18 ± 0.02 mm) were observed. In contrast, 1 month after tissue photodisruption corneas showed an average decrease of thickness (group 2: -21.0 ± 2.5 μm). By 6 months post-treatment, a further decrease (group 2: -36.3 ± 6.9 μm) was seen that remained stable for the rest of the observation period. At 176 days post-treatment, a decrease of corneal curvature (group 2: -0.21 ± 0.10 mm) was found. Slit-lamp examination revealed a transparent cornea. At the site of intrastromal photodisruption a narrow band of increased reflectivity could be detected.

CONCLUSIONS

Corneal thinning can be reliably achieved using intrastromal tissue modeling with a fs laser. Tissue modeling was accompanied by a transient opacity and irregularity of the corneal surface.

Early flap displacement after LASIK

PURPOSE

To evaluate the risks of flap displacement after LASIK.

DESIGN

Retrospective case series.

PARTICIPANTS

We included 41 845 consecutive adults who underwent LASIK surgery at Optical Express in the United Kingdom, including 81 238 eyes, of which 14 555 were hyperopic and 66 681 myopic or mixed astigmatic. We treated 57 241 eyes with the IntraLase FS-60 femtosecond laser and 23 997 with the Moria S.A. ONE Use-Plus automated microkeratome.

METHODS

We calculated the incidence of all flap displacements in the study population during an observational time period of ≥12 months after surgery. Independent variables were entered into logistic regression models to identify risk factors. Postoperative outcomes were assessed.

MAIN OUTCOME MEASURES

The incidence and odds ratios (OR) of flap displacement in the study population and in categories of refractive error and flap surgery technique.

RESULTS

The incidence of flap displacements was 10 in 81 238 LASIK procedures (0.012%), including 8 hyperopic eyes (0.055%) and 2 myopic eyes (0.003%). All flap displacements occurred within 48 hours of surgery and none were preceded by ocular trauma. They were classified as "early flap displacements" (EFD). The incidence of EFD after microkeratome surgery was 0.033% (n = 8), and after femtosecond laser it was 0.003% (n = 2). In hyperopic eyes having microkeratome surgery, the incidence was 0.179% (n = 7). In a logistic regression model, the strongest predictor of EFD after LASIK was hyperopia, recording an OR of 19.29 (P<0.001). The OR of developing an EFD after microkeratomy was 10.53 times higher than after femtosecond laser (P<0.005). In hyperopes, the OR of an EFD was 18.87 times higher after microkeratomy than after femtosecond treatment. Four of 10 displaced flaps needed secondary surgery, and 1 eye lost 2 lines of best-corrected visual acuity.

CONCLUSIONS

The incidence of flap displacements during a 12-month period after LASIK was extremely low (0.012%). Although the small number of displacements with the femtosecond laser limits conclusions, the risk of EFD was higher after microkeratome surgery than femtosecond laser.

[Infectious keratitis in 266,191 laser in situ keratomileusis]

OBJECTIVE

To study the incidence of infectious keratitis (IK) after laser-assisted in situ keratomileusis (LASIK), along with its diagnosis, therapeutic action taken, its management and the results.

MATERIAL AND METHOD

We carried out a retrospective study of 262,191 eyes intervened consecutively with LASIK, in our 20 centres, during the period from September 2002 and December 2009. All the cases susceptible to being diagnosed with IK, either clinically or due to the biological findings were analysed.

RESULTS

A total of 82 cases were found with infectious keratitis, which assumed an incidence of 0.031%. Distributions are presented by gender, mean age of the patients, mean days since the surgery, the clinical signs and symptoms, predisposing factors, therapeutic action, complications, details of the causal germ, and the loss of lines of vision.

CONCLUSIONS

Infectious keratitis after LASIK is a rare complication. The early diagnosis and management of the process are determining factors when establishing the prognosis. In our series all the cases were resolved without causing any other serious complications.

Traumatic Flap Striae 6 Years After LASIK: Case Report and Literature Review

Purpose:

To report a case of traumatic flap striae without flap dislocation 6 years after LASIK and provide a literature review of surgical flap striae, late traumatic flap striae, and their management.

Methods:

A 28-year-old man presented with late traumatic flap striae without concurrent flap dislocation, which closely approximated the longest reported interval between LASIK and the development of flap striae.

Results:

In the absence of flap dislocation, the finding of striae alone was subtle and went undetected initially. The flap was successfully refloated, stretched, and smoothed with recovery of 20/20 vision.

Conclusions:

Traumatic LASIK flap complications may occur many years after the original procedure. This report presents the first case of late traumatic flap striae without concurrent flap dislocation. Proper management can restore good visual function.

Central toxic keratopathy

PURPOSE OF REVIEW

To describe recent evidence from the literature regarding central toxic keratopathy syndrome (CTK).

RECENT FINDINGS

CTK describes a rare, self-limited, noninflammatory postsurgical condition that presents with central corneal opacity and a significant hyperopic shift. Although its cause remains uncertain, CTK bears a striking clinical resemblance to other more serious conditions and is, therefore, often misdiagnosed and mismanaged. Despite its noninflammatory nature, the overlapping clinical features CTK shares with other inflammatory and infectious processes have led some to treat CTK with steroids. Recent studies discourage the use of steroids in CTK and recommend allowing the condition to resolve on its own.

SUMMARY

Although CTK resembles other inflammatory conditions that are responsive to steroids, current studies suggest that steroid administration is contraindicated in CTK and can exacerbate preexisting refractive alterations in patients with the condition.

Resident laser refractive surgery training

PURPOSE OF REVIEW

The Residency Review Committee Ophthalmology of the Accreditation Council for Graduate Medical Education has recently established guidelines pertaining to the minimum operative requirements for training ophthalmology residents in refractive surgery. Despite being one of the most frequently performed ophthalmic surgical procedures, there is a paucity of literature on residency training in refractive surgery. Moreover, the literature indicates that only half of training programs offer surgical exposure to trainees. The purpose of this article is to review recent research on training ophthalmology residents in refractive surgery and offer an approach to incorporating laser refractive surgery curriculum in residency education.

RECENT FINDINGS

Kwon et al. performed a national survey to evaluate current trends in resident laser in-situ keratomileusis (LASIK) training in the USA. The result shows that 54% of respondents had resident-performed LASIK surgery with 9.1% of surveyed programs not offering any LASIK experience. In addition, residents in the study performed a mean of 4.4 LASIK surgeries (range 1-10) during residency training starting during the second year.

SUMMARY

The data emerging from the survey show that refractive surgery experience is fundamental to the education of the ophthalmology resident. Although the demand for refractive surgery continues to gain pace with millions of such procedures performed worldwide, only a little over half of ophthalmology residency programs offer residents the opportunity to gain surgical experience. With the current mandate, programs must now look for strategies to provide laser refractive surgical experience to residents.

Brevundimonas vesicularis keratitis after laser in situ keratomileusis

A 45-year-old woman developed a corneal infiltrate 14 months after laser in situ keratomileusis (LASIK) enhancement in the left eye. The LASIK flap was lifted, scraped, and irrigated with fortified vancomycin and ceftazidime. Scraped samples were cultured and grew Brevundimonas vesicularis. The patient remained on topical ceftazidime until improvement was noted and was then switched to topical levofloxacin. The keratitis resolved on antibiotic agents with strong gram-negative coverage and a steroid. To our knowledge, this is the first report of a B vesicularis ocular infection.

Incidence of epithelial ingrowth in primary and retreatment laser in situ keratomileusis

PURPOSE

To analyze the risk for clinically significant epithelial ingrowth after primary laser in situ keratomileusis (LASIK) and flap-lift retreatment LASIK.

SETTING

Private practice, Beverly Hills, California, USA.

METHODS

All cases of primary and flap-lift retreatment LASIK performed by the same surgeon in a single surgical center between January 2004 and June 2007 were retrospectively reviewed. Cases that subsequently developed clinically significant epithelial ingrowth, defined as epithelial ingrowth impeding on the visual axis and negatively affecting uncorrected or corrected distance visual acuity, were identified and analyzed.

RESULTS

Clinically significant epithelial ingrowth occurred in none of the 3866 primary LASIK cases and in 15 (2.3%) of the 646 flap-lift retreatment cases (P<.0001). Clinically significant ingrowth was more frequent when flap-lift retreatment was performed 3 or more years after primary LASIK (7.7% versus 1.0%) (P = .0001). Patient age and sex did not have a statistically significant effect on the epithelial ingrowth rate. There was a nonsignificant trend toward increased epithelial ingrowth after flap-lift retreatment of Automated Corneal Shaper (ACS) microkeratome flaps.

CONCLUSION

Flap-lift retreatment performed 3 or more years after primary LASIK led to a higher risk of clinically significant epithelial ingrowth than primary LASIK or earlier flap-lift retreatment.

FINANCIAL DISCLOSURE

The author has no financial or proprietary interest in any material or method mentioned.

Interface Haze Formation After Ultra Thin Flap Laser in Situ Keratomileusis

In this case series, five patients (10 eyes) underwent laser in siter keratomileusis (LASIK) for the correction of moderate myopia and astigmatism with the Schwind Carriazo Pendular microkeratome 90 mum head. Flap (superior hinged) thickness measured intraoperatively was assessed less than 70 mum in all eyes. On first month's postoperative examination, subepithelial mild corneal haze with consequent myopic regression was found in all patients. A significant improvement of haze formation and residual refractive error were observed during the following postoperative months. In conclusion, post-LASIK subepithelial corneal haze after thin flap creation is a temporarily potential complication that could affect patient's refractive error during the first postoperative month.

Effect of topical 0.5% morphine on postoperative pain after photorefractive keratectomy

PURPOSE

To investigate safety and efficacy of 0.5% morphine drops for pain control after photorefractive keratectomy (PRK).

METHODS

In a double-blind prospective study, 40 patients were randomized to either 0.5% morphine drops (n=20) or vehicle control (n=20). Treatment occurred every 2 hours following PRK on the day of the procedure, then four times daily on postoperative days 1 through 3. Patients completed pain assessment questionnaires (visual descriptor, numerical rating, visual analog scales, and oral analgesic consumption) every 2 hours while awake during the treatment period. Daily average and maximum scores were compared between the two groups. Patients were examined daily for 4 days after PRK, weekly for 4 weeks, then monthly for 3 months. Epithelial healing, corneal haze, and refractive outcomes were compared.

RESULTS

Both average and maximum pain scores were lower in the morphine group than in the vehicle control group on all scales and during all 4 days after PRK. Statistical significance (P<.05) was reached on numeric rating scale on procedure day and on postoperative day 1. The difference between the groups on the visual analog scale was statistically significant on procedure day, and on postoperative days 1 and 2. Oral analgesic consumption was higher in the vehicle control group on postoperative day 2. No difference between groups was noted in epithelial healing or refractive outcomes. Stromal haze scores were lower in the morphine group, but the difference was not statistically significant.

CONCLUSIONS

Topical 0.5% morphine may be an effective and safe method of pain control after PRK.

Infectious keratitis in 204 586 LASIK procedures

PURPOSE

To investigate the incidence, culture results, risk factors, and visual outcomes of infectious keratitis after LASIK, and examine treatment strategies.

DESIGN

Retrospective study.

PARTICIPANTS

We included 107 613 patients who underwent LASIK at Clínica Baviera (Instituto Oftalmológico Europeo, Spain) from September 2002 to May 2008.

METHODS

The medical records of post-LASIK patients (204 586 eyes) were reviewed to identify cases of infectious keratitis. Incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and final visual outcomes were recorded.

MAIN OUTCOME MEASURES

Incidence of post-LASIK infectious keratitis, culture results, response to treatment, and visual outcome.

RESULTS

Post-LASIK infectious keratitis was diagnosed in 72 eyes from 63 patients. Onset of infection was early (within 7 days after surgery) in 62.5% of cases. Cultures were positive in 21 of 54 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus epidermidis (9 cases). Immediate flap lifting and irrigation with antibiotics was performed in 54 eyes; late flap lifting was subsequently required in 10 out of 18 cases initially treated with topical antibiotics alone. One case required flap amputation owing to flap necrosis. Final best spectacle-corrected visual acuity (BSCVA) was >or=20/20 in 38 cases (52.7%) and >or=20/40 in 67 cases (93.05%); final BSCVA was <20/40 in 5 cases (6.94%).

CONCLUSIONS

The incidence of post-LASIK infectious keratitis was 0.035% per procedure. Infectious keratitis after LASIK is a potentially vision-threatening complication. The appearance of infections in asymptomatic patients highlights the need for a proper schedule of follow-up appointments. Prompt and aggressive management of this LASIK complication with early flap lifting, scraping, culture, and irrigation with antibiotics is strongly recommended. Proper management can result in preserving useful vision.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Incidence, management, and visual outcomes of buttonholed laser in situ keratomileusis flaps

PURPOSE

To describe the incidence, management, and visual outcomes of buttonholed laser in situ keratomileusis (LASIK) flaps.

SETTING

Private practice, Riyadh, Saudi Arabia.

METHODS

This retrospective review identified eyes that developed buttonholed flaps during LASIK. Preoperative, intraoperative, and postoperative data were obtained to identify factors predictive of this complication.

RESULTS

Of 4250 primary LASIK procedures, 17 eyes (0.4%) with buttonholed flaps were identified. Buttonholes occurred with the Hansatome microkeratome in 64.7% of eyes and with the Moria microkeratome in 35.3% of eyes, the incidence of buttonholed flaps was 0.62% and 0.19%, respectively (P = .03). Laser ablation was performed at the same time as buttonhole formation in 8 eyes (47.1%) and was aborted in the other eyes. Retreatment was performed in 10 eyes (58.8%); of retreated eyes, 6 had repeat LASIK and 3 had surface ablation. The final spherical equivalent refraction was -0.38 diopter +/- 0.79 (SD). Two eyes had a final loss of more than 2 lines of best corrected visual acuity (BCVA). The mean loss of BCVA lines was 0.72 in eyes that had complete LASIK, 0.62 in eyes that had aborted LASIK followed by retreatment with repeat LASIK, and 0.80 in eyes that had aborted LASIK followed by retreatment with surface ablation.

CONCLUSIONS

Buttonholed flaps occurred more frequently in the second of 2 consecutively treated eyes. Microkeratomes that produce a larger diameter flap were more likely to produce flap buttonholes. The least loss of BCVA was achieved when LASIK was aborted and then repeated after refractive stability.

Photorefractive keratectomy for refractory laser in situ keratomileusis flap striae

Photorefractive keratectomy (PRK) with mitomycin-C (MMC) was performed in 2 patients with visually significant, complicated laser in situ keratomileusis flap striae. These striae had been resistant to multiple treatments, including stretching, suturing, and PRK. The visual symptoms in both patients resolved after PRK with MMC, and both patients were stable 1 year later. Wavefront-guided PRK with MMC may be a viable treatment for patients who have complicated flap striae resistant to standard measures.

Early bacterial keratitis after presbyopic LASIK

PURPOSE

To report an unusual case of infectious keratitis that occurred after presbyopic laser-assisted in situ keratomileusis (LASIK).

METHODS

A 57-year-old woman presented with decreased visual acuity and pain in her right eye 2 days after a bilateral presbyopic LASIK procedure. Slit-lamp examination showed a large corneal infiltrate surrounded by marked corneal inflammation. Corneal scraping grew Propionibacterium acnes.

RESULTS

Under topical and systemic antibiotic treatment, the infiltrate slowly resolved. Visual acuity improved from counting fingers at presentation to 20/30 after 8 months of follow-up.

CONCLUSIONS

To the best of our knowledge, this is the first description of a P. acnes infection after LASIK and the first case of infection complicating a presbyopic LASIK procedure. Although infectious keratitis occurs rarely after refractive surgery, patients should be informed of the potential risk of visual loss caused by such infections.

Matched Population Comparison of the Visian Implantable Collamer Lens and Standard LASIK for Myopia of -3.00 to -7.88 Diopters

PURPOSE

To compare matched populations of LASIK and Visian Implantable Collamer Lens (ICL) cases in the correction of myopia between -3.00 and -7.88 diopters (D).

METHODS

One hundred sixty-four LASIK eyes with prospective data collected from a single center and 164 ICL eyes from the multicenter US ICL Clinical Trial were compared in this observational non-randomized study. The LASIK and ICL groups were well matched for age, gender, and mean level of preoperative spherical equivalent refraction.

RESULTS

At 6 months, best spectacle-corrected visual acuity (BSCVA) > or = 20/20 was 85% with LASIK and 95% with ICL (P = .003) compared to preoperative values of 93% and 88%, respectively (P = .292). Loss of > or = 2 lines of BSCVA was significantly lower with the ICL at 1 week (0.6% vs 10%, P < .001) and 1 month (7% vs 0%, P = .001) with comparable outcomes at 6 months (0% vs 1%). At 6 months postoperatively, uncorrected visual acuity (UCVA) > or = 20/15 (11% vs 25%, P = .001) and > or = 20/20 (49% vs 63%, P = .001) was better in the ICL cases. Predictability within 0.50 D at 6 months for ICL cases was 85% (67% LASIK, P < .001); 97% of ICL cases were within 1.00 D (88% LASIK, P = .002). Refractive stability (+/- 0.50 D) between 1 and 6 months was 93% with ICL compared to only 82% with LASIK (P = .006).

CONCLUSIONS

The ICL performed better than LASIK in almost all measures of safety, efficacy, predictability, and stability in this matched population comparison, supporting the ICL as an effective alternative to existing refractive laser surgical treatments for the range of myopia studied.

Buttonholes During LASIK: Etiology and Outcome

PURPOSE

To report the clinical features and outcome of eyes with flap buttonhole during LASIK.

METHODS

A retrospective review was performed to identify eyes that developed flap buttonhole during Hansatome microkeratome translation. Pre-, intra-, and postoperative data were obtained to identify factors predictive of buttonhole.

RESULTS

Five patients with buttonhole were identified from June 2001 through September 2002 (5 [0.06%] eyes of 7672 primary LASIK procedures). Mean patient age was 49.2 +/- 11.3 years (range: 37 to 66 years). Mean preoperative spherical equivalent refraction was 4.92 +/- 2.90 diopters (D) (range: -2.25 to -9.50 D). Mean keratometry was 45.59 +/- 1.15 D (range: 43.90 to 47.60 D). All 5 flap buttonholes occurred in the second of 2 consecutively treated eyes (P = .03). Buttonhole occurred in 2 (0.26%) of 778 eyes where the 160-microm microkeratome plate was used, and 3 (0.06%) of 4350 eyes where the 180-microm plate was used (P = .16). Two eyes received laser ablation at the time of buttonhole formation. In the untreated cases, the buttonhole flap itself caused a myopic spherical change of -0.50 D and 0.70 D of astigmatism. One of 5 eyes lost 2 lines of best spectacle-corrected visual acuity; this eye received laser ablation immediately after buttonhole formation.

CONCLUSIONS

Buttonholes are significantly more likely to occur in the second of two consecutively treated eyes. A new blade for the second eye when the flap in the first eye appears to be thin should be considered. Caution should be exercised when considering laser ablation immediately following buttonhole formation.

Ultrabiomicroscopy (UBM) in flap dislocation following LASIK: a case report

PURPOSE

To describe postoperative laser-assisted in situ keratomileusis (LASIK) flap dislocation occurred after trauma

METHODS

Ultrabiomicroscopy (UBM) is used to obtain a high-resolution imaging of the cornea.

RESULTS

The UBM results are presented and compared with histologic and confoscan findings

CONCLUSIONS

The technique is useful and easy to perform, offering more opportunities to study the anatomical changes in LASK flap dislocation occurred after trauma.

Infectious and noninfectious keratitis after laser in situ keratomileusis

PURPOSE

To retrospectively review the occurrence, treatment, and visual outcomes associated with various etiologies of keratitis as a postoperative complication of laser in situ keratomileusis (LASIK) at an academic surgical center.

SETTING

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

METHODS

The charts of 5618 post-LASIK patients (10 477 eyes) were reviewed for the development of keratitis. Occurrence rates, management regimens, and final best spectacle-corrected visual acuity (BSCVA) were reported for infectious and noninfectious keratitis etiologies.

RESULTS

Post-LASIK keratitis was diagnosed in 279 eyes. The keratitis was diagnosed as infectious in 33 eyes (12%) and as noninfectious in 246 eyes (88%). Infectious cases included 5 eyes (15%) with herpes simplex keratitis (HSV), 18 (55%) with adenoviral keratitis, and 10 (30%) with nonviral (including bacterial, fungal, and parasitic) keratitis. Of noninfectious cases, 193 (78%) were classified as diffuse lamellar keratitis (DLK), 36 (15%) as staphylococcal marginal hypersensitivity, and 17 (15%) as localized debris-related keratitis.

CONCLUSIONS

The occurrence of post-LASIK keratitis was 2.66%, with DLK being the most common diagnosis overall. The occurrence of noninfectious keratitis (2.34%) was 7.5 times greater than the occurrence of infectious keratitis (0.31%). Adenoviral keratitis had the best visual outcomes overall, with all 18 patients achieving 20/20 BSCVA. In contrast, all 5 eyes with HSV keratitis lost 1 or 2 lines of BSCVA. Excluding adenoviral keratitis, infectious etiologies had significantly worse visual outcomes than noninfectious etiologies at the 20/40 and 20/20 levels (P = .0013 and P<.001, respectively).

LASIK Flap Characteristics Using the Moria M2 Microkeratome With the 90-µm Single Use Head

PURPOSE

To evaluate the accuracy and consistency of corneal flap thickness, horizontal diameter, and hinge size with the Moria M2 90-microm single use head.

METHODS

Fifty-two myopic patients (104 eyes), mean age 32.6 years, underwent bilateral LASIK with a superior hinged flap using the Moria M2 microkeratome (90-microm single use head). Prospective evaluation included flap thickness (subtraction method), diameter, hinge size, interface particles, intraoperative complications, and visual recovery.

RESULTS

The mean preoperative spherical equivalent refraction was -5.72 +/- 2.59 diopters (D) (range: -2.88 to -10.75 D) and -5.84 +/- 2.73 D (range: -3.13 to -9.38 D) for right and left eyes, respectively. The mean preoperative central corneal thickness was 548 +/- 24 microm and 547 +/- 25 microm for right and left eyes, respectively. The mean preoperative steepest K was 44.12 +/- 1.28 D and 44.41 +/- 1.27 D for right and left eyes, respectively. Corneal diameter (white-to-white) was 12 +/- 0.4 mm and 11.9 +/- 0.4 mm for right and left eyes, respectively. The mean postoperative flap thickness was 109 +/- 18 microm (range: 67 to 152 microm) and 103 +/- 15 microm (range: 65 to 151 microm) for right and left eyes, respectively. The mean postoperative flap diameter was 9.4 +/- 0.3 mm (expected mean according to the nomogram given by the company was 9.5 mm). The mean postoperative hinge chord was 4.4 +/- 0.4 mm (expected mean 4.2 mm). No interface particles were detected on slit-lamp examination.

CONCLUSIONS

The Moria M2 90-microm single use head is safe with reasonable predictability for LASIK flap creation.

Evidence for Superior Efficacy and Safety of LASIK over Photorefractive Keratectomy for Correction of Myopia

PURPOSE

To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia.

DESIGN

Meta-analysis/systematic review.

PARTICIPANTS

Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database.

METHODS

A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken.

MAIN OUTCOME MEASURES

Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20).

RESULTS

Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001).

CONCLUSIONS

LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.

Long-term results of superficial laser in situ keratomileusis after ultrathin flap creation

PURPOSE

To study the long-term efficacy, safety, and stability of laser in situ keratomileusis (LASIK) after unintentional ultrathin flap creation less than 80 mum.

SETTING

University refractive surgery center.

METHODS

This retrospective case series comprised 25 patients (33 eyes) who had LASIK after flap creation less than 80 mum with the Moria M2 disposable microkeratome (head 90 microm). Flap thickness was measured with intraoperative ultrasound pachymetry. Manifest refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, predictability, stability, complications, patient satisfaction, and confocal microscopy images were studied.

RESULTS

The mean follow-up was 14.58 months +/- 3.73 (SD) (range 12 to 25 months). The mean flap thickness was 72.1 +/- 5.9 microm (range 58 to 80 microm), and the mean preoperative spherical equivalent (SE) refraction was -5.59 +/- 2.01 diopters (D) (range -10.25 to -3.25 D). On the first postoperative day, the UCVA was 20/25 or better. The SE manifest refraction was 1.00 D or less in all patients. The mean SE manifest refraction was -0.75 +/- 0.55 D (range -1.00 to +0.75 D) (P < .01). At the last follow-up, changes in visual acuity and manifest refraction were not statistically significant; no late postoperative complications were observed. All patients were satisfied with the final outcome. Qualitative analysis of confocal microscopy images revealed interface particles and activated keratocytes.

CONCLUSIONS

Despite the small sample and retrospective nature of the study, superficial LASIK seemed to be a safe and predictable technique for myopic refractive corrections. Patients were satisfied with the results and had rapid visual recovery with no intraoperative or early or late postoperative complications. If the safety and efficacy of an ultrathin flap are confirmed by additional studies, superficial LASIK could represent a new approach that combines the advantages of surface and lamellar procedures.

Diffuse lamellar keratitis induced by toxic chemicals after laser in situ keratomileusis

PURPOSE

To assess whether toxic chemicals produced during autoclaving sterilization were 1 of the main causes of diffuse lamellar keratitis (DLK) and to analyze the clinical outcomes of patients developing DLK after laser in situ keratomileusis (LASIK) treated with intensive topical corticosteroids.

SETTING

Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.

METHODS

A total of 14 eyes of 7 patients received technically smooth LASIK and developed DLK, including 6 severe and 8 mild DLK cases. In all eyes the same microkeratome was used; it was contaminated with toxic chemical materials produced accidentally by coautoclaving instruments and a foam piece.

RESULTS

Six eyes of 3 patients developed severe DLK on the same day, and 8 eyes of 4 patients developed mild DLK during the next LASIK surgery. After intensive topical corticosteroid treatment, lamellar infiltrates disappeared in 3 days in mild DLK eyes and 2 weeks in severe DLK eyes. No eye was treated with flap lifting and interface irrigation. For grade 4 DLK, the corneal opacity and flap folds disappeared in 4 weeks. There were no instances of permanent corneal scarring or loss of best spectacle-corrected visual acuity.

CONCLUSIONS

Toxic chemicals produced during instrument autoclaving sterilization are a possible cause of DLK. Immediate diagnosis and treatment with intensive corticosteroid drops are critical and can resolve severe DLK.

Role of topical fluoroquinolones on the pathogenesis of diffuse lamellar keratitis in experimental in vivo studies

PURPOSE

To investigate the potential role of commercially available topical fluoroquinolones in diffuse lamellar keratitis (DLK) using New Zealand White rabbit models.

SETTING

Campbell Ophthalmic Microbiology Laboratory at the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

METHODS

In a DLK challenge model, laser in situ keratomileusis flaps were created by a microkeratome in rabbit eyes (n = 10 per group) and the stromal beds were treated with 1 drop of Ciloxan (ciprofloxacin 0.3%), Ocuflox (ofloxacin 0.3%), balanced salt solution (BSS), or Pseudomonas aeruginosa endotoxin before flap closure. After the procedure, eyes were treated with the same drugs 4 times daily. On postoperative day 1, the eyes were examined by slitlamp and graded (modified Linebarger DLK grading scale) in a masked fashion. In a DLK exacerbation model, all eyes received 1 drop of endotoxin on the stromal interface followed by flap closure. After the procedure, the rabbit eyes (10 per group) were treated 4 times daily with Ciloxan, Ocuflox, or BSS and graded for DLK on postoperative day 1 as before.

RESULTS

In the challenge model, Ciloxan, Ocuflox, and endotoxin all produced higher median DLK scores than the BSS control (P = .02). Ciloxan produced significant DLK in more eyes and had higher median scores (70%, 1.0) than Ocuflox (40%, 0.5) or endotoxin (45%, 0.5) (P = .05). In the endotoxin-induced model, Ciloxan produced significantly higher DLK scores than Ocuflox or BSS (P = .05).

CONCLUSIONS

Topical fluoroquinolones caused and exacerbated DLK in rabbit models. Ocuflox was associated with less DLK than Ciloxan. The clinical significance of these findings can only be assessed in clinical trials.

Fourth-generation fluoroquinolone-resistant bacterial keratitis after refractive surgery

We report the first 2 cases of bacterial keratitis resistant to fourth-generation fluoroquinolones after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). The first patient had Pseudomonas aeruginosa keratitis after PRK despite treatment with moxifloxacin. The second patient was on gatifloxacin post-LASIK when she had methicillin-resistant Staphylococcus aureus (MRSA) keratitis diagnosed. In both cases, culture susceptibilities showed isolates resistant to moxifloxacin and gatifloxacin, and treatment with topical aminoglycosides and surgical intervention was necessary to effect a cure. These cases show the potential limitations in the coverage of these antibiotics.

Late Traumatic Flap Dislocations After LASIK

PURPOSE

To report the management and outcome of late onset traumatic dislocation of LASIK flaps.

METHODS

This retrospective, interventional case series presents three patients with late onset LASIK flap dislocation following mechanical trauma 1 to 7 years postoperatively.

RESULTS

In all cases, the flap was surgically repositioned. Epithelial ingrowth was removed and diffuse lamellar keratitis was treated with an intensive steroid regimen. All patients returned to their preoperative best spectacle-corrected visual acuity. Aggressive steroid treatment during the perioperative period and meticulous handling of the epithelium are important in preventing further recurrence.

CONCLUSIONS

Laser in situ keratomileusis flaps may experience mechanical dislocation as late as 7 years postoperatively. Diffuse lamellar keratitis and epithelial ingrowth are associated with flap dislodgment.

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.

Stage 4 diffuse lamellar keratitis after laser in situ keratomileusis

In March 1999, a 35-year-old woman had uneventful laser in situ keratomileusis in both eyes on the same day. Five days postoperatively, slitlamp biomicroscopy of the left eye showed an appearance similar to haze after photorefractive keratectomy, with greater density at the center and striae convergent toward the infiltrate (stage 4 diffuse lamellar keratitis [DLK]). The patient received treatment with dexamethasone 0.2% eyedrops every 2 hours. After 2 weeks, visual acuity was better and improvement was evident on topography, pachymetry, and slitlamp photography. The improvements were more marked at 6 months and 1 year. There was a progressive increment in corneal thickness and consequent improvement in corneal transparency, curvature, and regularity. This case, in which continuous morphologic adaptation of the cornea occurred, indicates that observation, rather than intervention, is a valid therapeutic option for stage 4 DLK.

A Standardized Drawing Scheme to Document Corneal Changes Following Refractive Corneal Surgery

PURPOSE

To present a systematic and standardized drawing scheme for unambiguous and reproducible documentation of corneal changes after incisional techniques, coagulative procedures, and lamellar and surface ablation excimer surgery.

METHODS

Standardized symbols in five colors representing specific corneal conditions after incisional surgery (eg, radial keratotomy, astigmatic keratotomy), coagulative procedures (eg, laser thermokeratoplasty, conductive keratoplasty), surface ablation (eg, photorefractive keratectomy, laser subepithelial keratomileusis, epi-LASIK), and LASIK are used to record corneal changes in frontal and sectional views.

RESULTS

Corneal changes following refractive corneal surgery were documented.

CONCLUSIONS

The drawing scheme permits specific features to be followed in the clinic in a clear and unambiguous manner.