Incidence of intraoperative flap complications in laser in situ keratomileusis

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.

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.

Femtosecond laser versus mechanical microkeratome for LASIK: a randomized controlled study

PURPOSE

To compare corneal haze (backscattered light) and visual outcomes between fellow eyes randomized to LASIK with the flap created by a femtosecond laser (bladeless) or with the flap created by a mechanical microkeratome.

DESIGN

Randomized, controlled, paired-eye study.

PARTICIPANTS

Twenty-one patients (42 eyes) received LASIK for myopia or myopic astigmatism.

METHODS

One eye of each patient was randomized to flap creation with a femtosecond laser (IntraLase FS, IntraLase Corp., Irvine, CA) with intended thickness of 120 microm, and the fellow eye to flap creation with a mechanical microkeratome (Hansatome, Bausch & Lomb, Rochester, NY) with intended thickness of 180 microm. Patients were examined before and at 1, 3, and 6 months after LASIK.

MAIN OUTCOME MEASURES

Corneal backscatter, high-contrast visual acuity, manifest refractive error, contrast sensitivity, and intraocular forward light scatter were measured at each examination. Flap thickness was measured by confocal microscopy at 1 month, and patients were asked if they preferred the vision in either eye at 3 months.

RESULTS

Corneal backscatter was 6% higher after bladeless LASIK than after LASIK with the mechanical microkeratome at 1 month (P = 0.007), but not at 3 or 6 months. High-contrast visual acuity, contrast sensitivity, and forward light scatter did not differ between treatments at any examination. Flap thicknesses at 1 month were 143+/-16 microm (bladeless, mean +/- standard deviation) and 138+/-22 microm (mechanical microkeratome), with no statistical difference in variances. At 3 months, 5 patients preferred the bladeless eye, 7 patients preferred the microkeratome eye, and 9 patients had no preference.

CONCLUSIONS

The method of flap creation did not affect visual outcomes during the first 6 months after LASIK. Although corneal backscatter was greater early after bladeless LASIK than LASIK with the mechanical microkeratome, patients did not perceive a difference in vision.

Confocal Microscopy Comparison of IntraLase Femtosecond Laser and Moria M2 Microkeratome in LASIK

PURPOSE

To analyze the quality of LASIK flaps created using a femtosecond laser or a mechanical microkeratome.

METHODS

A prospective study of consecutive bilateral LASIK flaps (100 patients) created with a 15 kHz femtosecond laser (IntraLase) or with a mechanical microkeratome (Moria M2) was performed. Outcome measures included visual and refractive outcomes, flap dimensions, and intraoperative complications. The first consecutive ten patients (20 eyes) were examined using confocal microscopy 1 and 3 months following surgery.

RESULTS

No significant differences were noted in the visual outcomes between groups (t test, P > .05 for all comparisons). Analysis of superficial measurements revealed more round flaps and greater predictability in surface dimensions for the femtosecond laser group (t test, P = .016). Mean deviation of flap thickness from target was the same for both instruments, 10 microm, with greater variability for the mechanical microkeratome. The incidence of diffuse lamellar keratitis was significantly greater in the femtosecond laser group (17%) than in the mechanical group (0%) (chi-square test, P < .001). Confocal microscopy revealed a higher wound healing opacity index in the femtosecond laser group.

CONCLUSIONS

Although the clinical results are similar, the femtosecond laser produces LASIK flaps with more accurate dimensions compared to the mechanical microkeratome.

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.

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.

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.

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.

Identical excimer laser PTK treatments in rabbits result in two distinct haze responses

PURPOSE

To obtain objective light-scattering measurements to test a hypothesis that identical PTK treatments cause distinct low- and high-level light-scattering responses in rabbit corneas.

METHODS

An excimer laser was used to produce identical 6-mm diameter phototherapeutic keratectomy treatments (PTK) in 32 pigmented rabbits. Eyes were treated by performing a 40-microm epithelial ablation, followed by a 100-mum stromal PTK. Objective scattering measurements were made before treatment, weekly up to 5 weeks, and then biweekly to 9 weeks. Confocal microscopy was performed on several corneas at 4 and 7 weeks.

RESULTS

Mean scattering levels split into distinct low- and high-scattering groups 2 weeks after treatment and remained distinct until week 7 (P < 0.003). Scattering in the low group reached a broad peak that lasted from weeks 2 to 4 at approximately 3 times the pretreatment level. Scattering in the high group peaked at 3 weeks at approximately 12 times the pretreatment level. Scattering levels diminished after reaching their peaks. Confocal images showed a band of highly reflective material in the anterior stroma that extended much deeper in corneas from the high group. The reflective band in the highly scattering corneas obscured the posterior stroma from view for up to 5 weeks.

CONCLUSIONS

Quantitative scattering data obtained with the scatterometer suggest that identical PTK treatments indeed result in distinct low- and high-level light-scattering responses in rabbits.

Keratectasia After LASIK But Not After PRK in One Patient

PURPOSE

To report a case of keratectasia in a patient who underwent LASIK in the right eye and photorefractive keratectomy (PRK) in the left eye for correction of compound myopic astigmatism.

METHODS

A 30-year-old man underwent LASIK in the right eye and PRK in left eye for refraction of -1.75 -1.50 x 48 degrees and -1.00 -1.75 x 100 degrees, respectively. Preoperative corneal thickness was 447 microm in the right eye and 446 microm in the left eye.

RESULTS

Postoperative corneal thickness decreased to 341 microm and 384 microm in the right and left eye, respectively. Uncorrected visual acuity in the left eye was 20/20, but the right eye developed keratectasia, which led to severe visual loss (20/400).

CONCLUSIONS

Photorefractive keratectomy may be better than LASIK for ablative refractive surgery for low myopic astigmatism in eyes with low central corneal thickness.

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.

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.

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.

Bilateral Comparison of Corneal Flap Dimensions With the Moria M2 Reusable Head and Single Use Head Microkeratomes

PURPOSE

To compare the Moria (Antony, France) M2 automated microkeratome with the head 130 to a new disposable single use head to evaluate complications, accuracy, and safety of the procedure.

METHODS

Ninety-eight eyes of 49 consecutive patients were operated with the Moria M2 microkeratome. One eye was operated with the metallic head 130 and the other with a plastic single use head, both designed to create a 160-microm flap. Intraoperative flap dimensions were correlated to preoperative parameters and evaluated 1 month postoperatively.

RESULTS

With the head 130, mean thickness was 153.3 microm (standard deviation [SD] 13.3, range: 102 to 179 microm). When using a single use head, mean thickness was 148.0 microm (SD 9.8, range: 120 to 170 microm). Occasional iron particles were observed in one eye with both head types. No true epithelial ingrowth was detected in any of the eyes, but epithelial dots at the wound edge occurred in one eye, when using the head 130, but not in the eyes operated with a single use head.

CONCLUSIONS

On average, both head types created thinner flaps than attempted. Single use heads produced thinner flaps than the head 130. Accuracy in flap thickness in terms of standard deviation was significantly better in single use heads than in the head 130. Single use heads also had fewer microkeratome-related complications. In clinical practice, the single use head was easier to use because no assembly was required. Plastic single use heads also worked more smoothly than the metallic head 130.

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.

Confocal Microscopy of Disposable and Nondisposable Heads for the Moria M2 Microkeratome

PURPOSE

To study the quality of the flap obtained with two different heads, disposable and nondisposable, and two different speeds, low and high, using the same Moria M2 microkeratome (Moria, Antony, France).

METHODS

In a prospective randomized study, 51 consecutive eyes (28 patients) underwent myopic LASIK (-4.39 +/- 2.15 diopters). The eyes were randomly assigned to four groups related to cutting head model (disposable and nondisposable) and cut speed (low and high). In all cases, the intended cut was 160 microm and the same M2 unit was used. During surgery, superficial measurements of the flap and the surgeon's opinion about the quality of the cut were recorded. One month after LASIK, the cut depth, interface particle density, and transparency of the cornea (confocal wound healing opacity index) were measured with a confocal microscope.

RESULTS

Flaps performed with a disposable cutting head and high speed were statistically significantly larger than the flaps created in the other groups (Kruskal-Wallis test; P = .041). No statistical differences were noted in cut depth, number of particles, and wound healing opacity index. The surgeon's opinion parameters were similar in all groups.

CONCLUSIONS

The Moria M2 microkeratome is safe and provided reproducible results, regardless of cutting head and speed. Disposable and nondisposable head models were similar in their outcome in the quality control model used in this study.

Influence of laser in situ keratomileusis and laser epithelial keratectomy on patients' reading performance

PURPOSE

To evaluate the influence of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) on reading performance regarding reading acuity, reading speed based on print size, maximum reading speed, and critical print size.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, and Auge-und-Laser, Medicent Baden, Austria.

METHODS

Fifty-two eyes of 34 patients (26 eyes per group) were studied. Best corrected LogMAR visual acuity (Early Treatment Diabetic Retinopathy Study charts), reading acuity, and reading speed were tested monocularly before LASIK or LASEK and 3 weeks after surgery. Reading acuity (LogRAD) and reading speed were determined with the standardized Radner reading charts.

RESULTS

Preoperatively, the distance visual acuity and reading acuity were comparable between the LASIK and LASEK patients. Reading speed measurements also showed no statistical difference. Three weeks after refractive surgery, no statistically significant differences in the preoperative measures and between the 2 surgical procedures could be found in any tested parameters. The mean distance visual acuity was LogMAR -0.02 +/- 0.06 (SD) (LASIK) and LogMAR -0.05 +/- 0.07 (LASEK). The mean reading acuity was LogRAD 0.00 +/- 0.12 (97.7% of LogMAR) (LASIK) and LogRAD 0.04 +/- 0.16 (93.7% of LogMAR) (LASEK). The mean maximum reading speed was 235 +/- 35 words per minute (LASIK) and 240 +/- 37 words per minute (LASEK), and the mean critical print size was at LogRAD 0.48 +/- 0.19 (LASIK) and 0.49 +/- 0.17 (LASEK).

CONCLUSIONS

In a standardized reading test setting, no significant effects of LASIK and LASEK on individual reading performance could be evaluated. This indicates that patients can expect to retain their normal visual function after refractive surgery with these 2 procedures under full light conditions.

Conductive keratoplasty to treat complications of LASIK and photorefractive keratectomy

PURPOSE

To assess the outcomes of conductive keratoplasty (CK) for patients with complications related to LASIK or photorefractive keratectomy (PRK).

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Sixteen eyes of 15 patients were treated using CK after complications of initial LASIK or PRK surgeries. Five cases are described in detail.

INTERVENTION

Rehabilitative CK was performed.

MAIN OUTCOME MEASURES

Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), refractive error, keratometry, topography analysis, and a subjective assessment of visual quality.

RESULTS

After CK treatment, there was a mean improvement in UCVA of 2 lines; 1 eye lost >1 line of UCVA. Best-corrected visual acuity improved or remained the same in 12 of 15 eyes; no eyes lost >1 line of BSCVA. There was a mean reduction in astigmatism of 54%. Videokeratography generally demonstrated improved quality of the corneal optical surface, and patients reported a reduction in optical symptoms such as glare and halo.

CONCLUSIONS

Conductive keratoplasty may give improved corneal optics and vision in patients with complications of LASIK or PRK. This application of CK offers an alternative in cases in which further flap manipulation or laser treatments are contraindicated.

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.

Moria M2 Single Use Microkeratome Head in 100 Consecutive LASIK Procedures

PURPOSE

To evaluate the safety and efficacy of the Moria M2 single use 130 microkeratome head in consecutive LASIK procedures for correction of myopia and myopic astigmatism.

METHODS

One hundred eyes of 55 patients underwent LASIK in which the flaps were created with the Moria M2 microkeratome using the single use 130 head and excimer laser ablation was done with the Allegretto Wave-light laser. Flap parameters measured were: thickness, diameter, hinge length, and overall quality. Preoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, wavefront aberrations, and low contrast sensitivity were compared to postoperative values at 6-month follow-up.

RESULTS

Mean flap thickness was 145 +/- 17.5 microm, mean flap diameter was 8.5 +/- 0.40 mm, and mean hinge cord length was 4.05 +/- 0.35 mm. At 6-month follow-up, UCVA improved from 20/200 (+/-0.24) to 20/18.5 (+/-0.12) and BSCVA improved from 20/20.5 (+/-0.18) to 20/17.5 (+/-0.11).

CONCLUSIONS

The Moria M2 single use 130 microkeratome head appears to be safe and effective in performing LASIK procedures.

Intraoperative management of partial flap during LASIK: a small case series report

PURPOSE

To report the intraoperative management of incomplete microkeratome LASIK flaps.

DESIGN

Small, retrospective, noncomparative, interventional case series.

PARTICIPANTS

Five outpatients.

METHODS

In 5 eyes of 5 patients, the premature stop of the microkeratome resulting from mechanical obstacles resulted in an incomplete flap that would not allow for the completion of the LASIK procedure. After the careful realignment of the partial flaps and the removal of the identified obstacles, the second pass of the microkeratome resulted in flaps of the intended size.

MAIN OUTCOME MEASURES

Final creation of a flap as intended, completion of the procedure, and visual and refractive outcome of the operative eyes.

RESULTS

The second pass of the microkeratome resulted in flaps as planned. All the procedures were completed, and the operative eyes that were followed up for at least 3 months had excellent visual and refractive results.

CONCLUSIONS

The second pass of the microkeratome can successfully manage incomplete flaps resulting from microkeratome premature stop as a result of mechanical obstacles.

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.

Amadeus microkeratome: experience with the first 2000 cases and lessons learned

BACKGROUND

To assess the safety and efficacy of the Amadeus microkeratome and to report on lessons learnt in optimizing results from its use.

METHODS

A retrospective review of the flap-related complications of 2000 laser in situ keratomileusis (LASIK) procedures performed by one surgeon using the Amadeus microkeratome (AMO, Irvine, CA, USA) was conducted. One hundred consecutive cases had preoperative and intraoperative pachymetry to evaluate the relationship between flap thickness, corneal thickness and reuse of the blade.

RESULTS

There were 35 cases of minor epithelial defects (1.8%) and four eyes with major epithelial defects (0.2%). There were no cases of suction loss, buttonholes, or incomplete or damaged flaps. There were four free caps (0.2%). Twenty-five cases had minor wrinkles and two cases had significant folds requiring relifts. Thinner corneas resulted in thinner flaps (P < 0.0001). Reuse of the blade resulted in thinner flaps (P = 0.0001).

CONCLUSION

The Amadeus is a safe and reliable microkeratome. Although short, there is a learning curve with use of the instrument. Corneal thickness and reuse of the blade affect flap thickness.

Thin flap laser in situ keratomileusis: analysis of contrast sensitivity, visual, and refractive outcomes

PURPOSE

To analyze refractive, visual, and contrast sensitivity outcomes of laser in situ keratomileusis (LASIK) performed under thin flaps (less than 100 microm), and compare them with those of conventional thicker flaps.

SETTING

Clínica Baviera, Instituto Oftalmológico Europeo, Madrid, Spain.

METHODS

This retrospective study comprised 280 consecutive eyes that had LASIK for myopia using the Moria LSK-One microkeratome and the Technolas 217C excimer laser. Efficacy, predictability, and contrast sensitivity indicators were compared between 3 groups of flap thickness: thin (<100 microm, n = 105), medium (100 to 129 microm, n = 122), and thick (>130 microm, n = 53).

RESULTS

Refractive results were excellent and comparable between the 3 groups; however, visual outcomes-measured as efficacy, postoperative evolution of uncorrected visual acuity, and contrast sensitivity-test were significantly better in the thin flap group. Efficacy results were 92.9%, 91.0%, and 81.0% in the thin, medium, and thick flap groups, respectively (P < .05), and the rate of enhancements was 0%, 2.3%, and 5.6%, respectively. With regard to contrast sensitivity, changes between preoperative and postoperative values at month 3 of follow-up, the thin flap group achieved the preoperative levels at 3 spatial frequencies (3, 6, and 18 cycles per degree), while the thicker flap groups maintained lower than preoperative levels at more than 2 spatial frequencies. When comparing contrast sensitivity values between the 3 groups, the thin flap group also obtained the best results at lower spatial frequencies.

CONCLUSIONS

Thin flap LASIK is a safe technique to correct myopic defects since it blends the advantages of surface and lamellar procedures (minimal debilitation of corneal biomechanical architecture with the rapid and comfortable visual recovery of lamellar approaches). Moreover, it achieves excellent refractive outcomes, a lower rate of enhancements, and a good visual performance with better contrast sensitivity test results.

Refractive outcomes of laser in situ keratomileusis after flap complications

PURPOSE

To study the refractive and visual outcomes, including surgically induced astigmatism, of laser in situ keratomileusis (LASIK) after flap buttonholes and incomplete flaps.

SETTING

Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.

METHODS

This was a retrospective case series of 15 patients (15 eyes) who had LASIK after flap complications (6 eyes with buttonholes and 9 with incomplete flaps). The second surgery was performed after the refraction was stable for 2 months. The refractive and visual outcomes were studied.

RESULTS

After the flap complication, the spheroequivalent did not change significantly (P = .78) but the mean pachymetry changed from 523.6 microm +/- 23.14 (SD) to 530.4 +/- 23.96 microm (P = .04) and the mean absolute cylinder changed from 0.63 +/- 1.01 diopter (D) to 0.88 +/- 0.87 D (P = .026). The second surgery was performed at a mean interval of 6.2 months (range 3 to 17 months). Two eyes had flap complications (irregular flaps) again after the second surgery. At the 6-month follow-up, the mean spheroequivalent was -0.34 +/- 0.65 D and the mean cylinder was 0.15 +/- 0.19 D x 83.6. Thirteen eyes (86.66%) were within 0.5 D of the attempted correction. Post-LASIK complications included diffuse lamellar keratitis (1 eye), epithelial ingrowth (1 eye), and flap striae (2 eyes). After the flap complication, no eye lost 2 or more lines of best spectacle-corrected visual acuity (BSCVA); but after the second surgery at 6 months, 1 eye had lost 2 lines of BSCVA. Six months postoperatively, all eyes had a BSCVA of 20/40 or better.

CONCLUSION

Laser in situ keratomileusis after flap complications is associated with good refractive and visual outcomes; however, there is a higher risk for intraoperative and postoperative complications after the second surgery.

Corneal Flap Measurements in Laser in situ Keratomileusis Using the Moria M2 Automated Microkeratome

PURPOSE

To evaluate accuracy and predictability and factors that influence the dimensions of the laser in situ keratomileusis (LASIK) corneal flap created with the Moria M2 automated microkeratome (Moria SA, Antony, France).

METHODS

The flap thickness of 454 eyes of 243 consecutive patients was measured using subtraction ultrasonic pachymetry during LASIK with the Moria M2 microkeratome head 130 designed to create a 160-microm-thick flap. Flap dimensions were evaluated and measurements were correlated with preoperative parameters. A stepwise regression analysis was used to determine the factors that influenced actual flap thickness.

RESULTS

The preoperative spherical equivalent refraction of the 454 eyes ranged from -12.125 diopters (D) to +6.25 D. Patient age ranged from 18 to 57 years (mean age: 31.3 +/- 8.8 years). Mean preoperative keratometric power K1 was 44.31 +/- 1.59 D and K2 was 43.32 +/- 1.54 D. Mean preoperative central comeal thickness was 552.4 +/- 32.5 microm (range: 466 to 665 microm). With an attempted thickness of 160 microm, the Moria M2 flap thickness ranged from 77 to 209 microm (mean: 153.3 +/- 19.0 microm). Mean horizontal flap diameter was 9.2 +/- 0.2 mm and mean hinge length 4.6 +/- 0.3 mm. Increasing flap thickness was found to correlate with increasing preoperative comeal thickness, younger patient age, and flatter preoperative keratometric power K1.

CONCLUSIONS

Although the standard deviation of the flap thickness was relatively small, remarkable individual variation was noted. Therefore, the intraoperative calculation of the remaining stromal bed is recommended. Furthermore, the consideration of central corneal thickness, patient age, and preoperative keratometry are helpful parameters to avoid too deep ablation.

Epithelial healing and clinical outcomes in excimer laser photorefractive surgery following three epithelial removal techniques: mechanical, alcohol, and excimer laser

PURPOSE

To evaluate epithelial healing, postoperative pain, and visual and refractive outcomes after photorefractive keratectomy (PRK) using three epithelial removal techniques.

DESIGN

Prospective, nonrandomized, comparative trial.

METHODS

SETTING

Department of Ophthalmology, Yonsei University College of Medicine and Balgensesang Ophthalmology Clinic, Seoul, Korea.

INTERVENTIONS

For the PRK procedure, the corneal epithelium was removed in one of three ways: mechanically (conventional PRK [PRK]) in 88 eyes of 44 patients; using excimer laser (transepithelial PRK [tPRK]) in 106 eyes of 53 patients; or using 20% diluted alcohol, laser-assisted subepithelial keratomileusis (LASEK) in 106 eyes of 53 patients.

MAIN OUTCOME MEASURES

Epithelial healing, postoperative pain, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and remaining refractive error.

RESULTS

The mean postoperative pain scores were 4.84 +/- 1.45 for PRK, 4.71 +/- 1.62 for tPRK, and 4.63 +/- 1.52 for LASEK (P = .125). The mean epithelial healing rates were 12.3 +/- 4.6 for PRK, 15.2 +/- 4.9 for tPRK, and 18.1 +/- 5.2 mm2/day for LASEK (P < .001). The postoperative 6-month remaining mean spherical equivalents (diopters) were -0.46 +/- 1.01 for PRK, 0.18 +/- 0.91 for tPRK, and -0.82 +/- 1.18 for LASEK (P = .01). The LASEK group showed less favorable UCVA than other groups. There was no significant difference in BSCVA between the groups.

CONCLUSIONS

Postoperative pain, subepithelial opacity and BSCVA were similar regardless of the epithelial removal procedure. A faster epithelial healing rate did not result in better visual or refractive outcomes. Using the same nomogram, tPRK resulted in a slight overcorrection, and LASEK resulted in a slight undercorrection.

Photorefractive keratectomy versus laser in situ keratomileusis to prevent keratectasia after corneal ablation

A 27-year-old man had excimer photoastigmatic keratectomy in the right eye and laser in situ keratomileusis in the left eye for the treatment of equivalent myopia. Preoperative slitlamp examination did not reveal evidence of keratoconus, central corneal pachymetry was 485 microm in the right eye and 500 microm in the left eye, and corneal topography revealed asymmetric bow-tie astigmatism with inferior steepening in the right eye and a small area of inferior steepening in the left eye. Twenty-two months after surgery, the patient complained of poor vision in the left eye. Slitlamp examination of the left eye revealed central corneal thinning and protrusion, with a Fleischer ring within the flap. Corneal topographic evaluation revealed a stable map in the right eye and central corneal steepening indicative of keratectasia in the left eye.

Interrupted sutures at the hinge site to manage a free flap during laser in situ keratomileusis

Two patients developed free flaps intraoperatively during laser in situ keratomileusis. After excimer laser treatment was performed, the free flap was replaced, maintaining proper alignment. Interrupted sutures were placed superiorly at the intended hinge site to secure the free flap. The uncorrected visual acuity was 20/30 in the affected eyes of both patients after treatment. At the 6-month follow-up, there were no flap-related complications and there was no loss of best corrected visual acuity.

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

PURPOSE

We evaluated the incidence and intraoperative microkeratome-related complications in laser in situ keratomileusis (LASIK).

METHODS

We present non-randomized, retrospective, comparative, interventional case series. We reviewed the records of patients who underwent LASIK from August 2000 to March 2004 at Excimer Laser Santa Cruz, São Paulo, Brazil (47,094 eyes). We identified 369 eyes (0.0078%) with an intraoperative complication. Data were collected regarding microkeratome, average keratometric power, and type of complication.

RESULTS

The Hansatome microkeratome was the most common microkeratome used (34,182 eyes; 73%), followed by the Automated Corneal Shaper-ACS (11,164 eyes, 24%) and the Nidek MK-2000 (1748 eyes, 3.7%). Intraoperative complications were more common with the ACS (1.26%) than with the Hansatome (0.63%) and MK-2000 (0.63%) (P<.001; P=.03; respectively). Complications included incomplete flaps (0.23%), buttonholes (0.13%), thin flaps (0.08%), and free flaps (0.08%). Buttonholes were more frequent with the ACS (0.34%) than with the Hansatome (0.06%) (P<.001) and free flaps were more common with the ACS (0.20%) and MK-2000 (0.29%) than with the Hansatome (0.04%) (P<.001). Keratometric power of eyes with intraoperative complications was significantly higher in the ACS group compared to the Hansatome group.

CONCLUSIONS

Intraoperative complications were more common with the ACS than with the Hansatome or MK-2000. Buttonholes were most frequent with the ACS, and the Hansatome had the lowest incidence of free flaps.

Ptosis after laser in situ keratomileusis

We present a patient who developed partial ptosis after laser in situ keratomileusis.

Quality assessment model of 3 different microkeratomes through confocal microscopy

PURPOSE

To study the quality of the cut created by 3 microkeratomes from 2 different generations using corneal confocal microscopy.

SETTING

Department of Refractive Surgery, Instituto Oftalmológico de Alicante, Alicante, Spain.

METHODS

Two different studies were conducted: Study 1 and Study 2. Study 1 was a prospective analysis using confocal microscopy examination data from 2 reference groups: Group A (control) with 20 nonoperated eyes of 20 healthy volunteers, and Group B with 50 eyes of 30 patients operated on with the Bausch & Lomb Automated Corneal Shaper (ACS) microkeratome. Study 2 was a prospective randomized double-masked study in which 40 eyes of 20 patients underwent myopic laser in situ keratomileusis by 1 surgeon. The right and left eyes of each patient were randomly and alternatively assigned to Group C, flap made with the Hansatome microkeratome, or Group D, flap made with the Moria M2. Immediately after surgery, the microscopic appearance of the cut was subjectively evaluated by the surgeon. One month postoperatively, flap thickness, particle density, and the subclinical confocal wound healing opacity (WHO) index were evaluated with the corneal confocal microscope.

RESULTS

Surgeon handling comfort was nearly the same with the Hansatome as with the M2 (P =.540). However, the apparent quality of the resulting flap was better with the M2 microkeratome (P =.041). The depth of the cuts made by the 3 microkeratomes were significantly different (P<.001), with the ACS flaps being thinner than the flaps made with the Hansatome or the M2. Particle density at the interface was significantly poorer in the eyes operated on with the ACS, but in these cases the WHO index was significantly greater (P<.001 in both cases).

CONCLUSIONS

Confocal microscopy is a very useful tool to evaluate the quality of the cut made by different microkeratomes. Overall, the predictability in flap thickness and the apparent quality of the cut made by the Moria M2 microkeratome are better than those obtained with the Hansatome or the ACS. The thin flap made by the ACS microkeratome produced a significantly greater WHO index than the thicker flaps created with the other 2 microkeratomes.

Risk factors and retreatment results of intraoperative flap complications in LASIK

PURPOSE

To evaluate the incidence, type, and risk factors of intraoperative complications leading to abandonment of laser in situ keratomileusis (LASIK), and to compare the safety and efficacy of retreated LASIK with uncomplicated primary LASIK.

SETTING

Refractive surgery centers in Tokyo, Yokohama, Nagoya, Osaka, and Fukuoka, Japan.

METHODS

A total of 3751 eyes of 2033 patients who were followed for 6 months after primary LASIK, of which 15 eyes were retreated after intraoperative flap complications, were reviewed. In most of the cases, retreatments were performed by recutting a new flap.

RESULTS

Intraoperative flap complications occurred in 25 eyes, of which 15 eyes had retreatment at a later date. The overall incidence of complications was independent of the surgeons' experience, although incomplete flaps, in particular, occurred at a higher rate in the hands of inexperienced surgeons. No patient profile was detected as a risk factor for intraoperative flap complications. No flap-related complications occurred at retreatment. Refractive and visual outcomes were comparable to those in the uncomplicated cases within 6 months postoperatively.

CONCLUSIONS

Retreatment after microkeratome flap complications by recutting the cornea is safe and effective.

Outcomes of Laser in situ Keratomileusis in a Refractive Surgery Fellowship Program

PURPOSE

The purpose of this study was to document the learning curve and evaluate the success of laser in situ keratomileusis (LASIK) performed by fellows in a Cornea/External Disease and Refractive fellowship program.

METHODS

Two surgeons performed LASIK within a fellowship training program between July 2000 and August 2001. A retrospective review was conducted to determine the visual outcomes and operative complications from this non-comparative case series of 755 consecutive eyes. All LASIK procedures were performed using a Bausch & Lomb Technolas 217A laser and the Bausch & Lomb Hansatome or the Automated Corneal Shaper microkeratome. All eyes were evaluated for operative complications. Visual acuity was reported with a minimum of 1 month follow-up.

RESULTS

Data analysis revealed that uncorrected visual acuity of 20/40 or better was attained in 99.4% of treated eyes, and 20/20 or better in 77.2%. With both eyes open, 100% of patients saw 20/30 or better, 94% saw 20/20 or better, 70% saw 20/15 or better, and 5.5% saw 20/10. Flap related complications occurred in 7 of 755 eyes (0.9%) and all were successfully treated. Forty-two eyes (5.6%) were lost to follow-up prior to the 1-month examination and were excluded from analysis of visual acuity.

CONCLUSIONS

Favorable operative and visual acuity 1-month results in 755 eyes after LASIK with the Bausch & Lomb Technolas 217A laser were in part due to a well organized system of education, patient examination, execution of surgery, and postoperative care. A team approach was essential.

Prospective, Paired Comparison of Laser in situ Keratomileusis and Laser Epithelial Keratomileusis for Myopia Less Than -6.00 Diopters

PURPOSE

To compare visual and refractive results, contrast sensitivity, and tear stability after laser in situ keratomileusis (LASIK) in one eye and laser epithelial keratomileusis (LASEK) in the fellow eye for low myopia.

METHODS

Patients diagnosed with low myopia, with a maximum difference of 1 D between their two eyes, were randomly assigned to receive LASEK on one eye and LASIK on the other eye. A total of 64 eyes of 32 patients with a mean age of 26.83 +/- 5.33 years were included in the study. Preoperative myopia ranged from -1.00 to -6.00 D. Follow-up was 6 to 12 months. Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), Schirmer test results, tear break-up time, corneal asphericity, corneal uniformity index, predicted corneal acuity, and contrast sensitivity values were compared with preoperative values. A Wilcoxon test was used for statistical comparisons and a P-value less than .05 was considered significant.

RESULTS

At 6 months after surgery, there was no statistically significant difference in UCVA, BSCVA, spherical and cylindrical refractive error, Schirmer test, or tear break-up time between groups. Contrast sensitivity values in the LASIK eyes were lower in comparison to preoperative values, but there was no change in the LASEK group.

CONCLUSIONS

Based on 6-month results, LASEK for low myopia was safe and effective with predictable results, offered early refractive stability, and may be considered an alternative for LASIK.

Influence of intraoperative epithelial defects on outcomes in LASIK for myopia

PURPOSE

To evaluate whether intraoperative epithelial defects have an adverse effect on achieving desired refractive outcomes following laser in situ keratomileusis (LASIK) for myopia.

DESIGN

Observational retrospective case control study.

METHODS

Thirty eyes that had intraoperative epithelial defects on the LASIK flap were compared with 60 randomly selected control eyes, matched for age, preoperative spherical equivalent, and preoperative cylinder, that had no intraoperative epithelial defects. Preoperative and postoperative clinical data were compared between the two groups. Statistical analyses were performed using analysis of means, analysis of variance, and the Student t test. Comparison variables included preoperative spherical equivalent, 3-month postoperative best-corrected visual acuity, attempted correction, amount of undercorrection at 3 months postoperatively, and whether LASIK enhancement was performed at 3 months postoperatively.

RESULTS

Eyes with intraoperative epithelial defects showed more undercorrection at 3 months (P =.005), were more likely to have lost lines of visual acuity (P =.003), and underwent more enhancement procedures at 3 months (P =.004) compared with control eyes.

CONCLUSIONS

Intraoperative epithelial defects during LASIK predispose eyes to increased wound healing, leading to myopic regression, irregular wound healing with loss of visual acuity, and increased need for enhancement procedures.

Effect of flap hinge placement on post-laser in situ keratomileusis wound healing in the presence of superior corneal vascularization

We report a case that demonstrates a difference in wound healing after laser in situ keratomileusis using microkeratomes with both superior and nasal hinges in a patient with bilateral superior corneal vascularization. Subsequently, the patient experienced lamellar keratitis, epithelial defects, and peripheral thinning in both eyes. These postoperative conditions were more extensive and required more time to resolve in the eye with a nasal hinge flap. Creating a superiorly hinged flap decreases the likelihood of transecting extensive corneal pannus and may reduce the degree of postoperative complications.

Inferior corneal steepening after a partial flap without laser ablation mimicking corneal ectasia

We report a patient with inferior steepening mimicking corneal ectasia that developed after 2 incomplete microkeratome cuts (partial or short flap) without laser ablation.

Photorefractive keratectomy for treatment of flap complications in laser in situ keratomileusis

PURPOSE

To present the results of photorefractive keratectomy (PRK) for treatment of laser in situ keratomileusis (LASIK) flap complications.

METHODS

Compilation of case reports through solicitation on Kera-net, an Internet surgery discussion site.

RESULTS

PRK was performed on 13 patients from 2 weeks to 6 months after LASIK flap complications. The technique used for the PRK varied. Epithelial removal was performed using no-touch phototherapeutic keratectomy (PTK) in six of the 13 patients and manual debridement in the other seven patients. A dilute solution of 20% ethanol was used to facilitate manual debridement in five of the seven patients. In two of these five patients, the epithelium was replaced as in laser-assisted subepithelial keratomileusis (LASEK). A solution of 0.02% mitomycin C was used after laser ablation to prevent haze formation in three patients. After an average 7 months of follow-up, uncorrected visual acuity was 20/20 in six patients, 20/25 in four patients, and 20/30 in two patients. The visual acuity in one patient was 20/80, purposely left undercorrected for monovision. Best spectacle-corrected visual acuity was 20/20 in 10 of 13 patients. Three patients were 20/25, losing one line of best spectacle-corrected visual acuity. On slit-lamp examination, at last follow-up appointment, stromal haze was graded from trace to none in all patients.

CONCLUSIONS

Photorefractive keratectomy is a safe and effective technique for treatment of patients with LASIK flap complications.

Six-year follow-up of laser in situ keratomileusis for moderate and extreme myopia using a first-generation excimer laser and microkeratome

PURPOSE

To evaluate objectively and subjectively the long-term outcome of laser in situ keratomileusis (LASIK) in patients with high and very high myopia.

SETTING

Department of Ophthalmology, Philipps University, Marburg, Germany.

METHODS

Thirty-three eyes of 19 patients were followed for a mean of 76 months (range 50 to 84 months) after primary LASIK using the Keratom I excimer laser (Schwind) and the ALK microkeratome (Chiron). Refraction, glare, pachymetry, corneal topography, and tear-film secretion and stability were measured. At the last examination, patients also answered a 14-item questionnaire.

RESULTS

Preoperatively, the mean spherical equivalent was -13.65 diopters (D). At 1 year, it was -0.25 D and after 6 years, -0.88 D. Fifteen percent of eyes lost > or =2 lines of best spectacle-corrected visual acuity (BSCVA), and 9% gained > or =2 Snellen lines. At the end of the study, 46% of eyes were within +/-1.0 D of the attempted corrected and 88% were within +/-3.0 D. There were 5 microkeratome-associated complications; 3 resulted in loss of BSCVA. The latest pachymetry showed a mean corneal thickness of 498.5 microm (range 396 to 552 microm). There were no cases of keratectasia. Seventy-five percent of patients noted an increase in their quality of life. Seventy-one percent were satisfied with their postoperative visual acuity; however, 75% noticed glare and halos at night.

CONCLUSIONS

Laser in situ keratomileusis correction of very high myopia did not cause keratectasia in the long term provided the corneal thickness was respected. A flap thickness setting of 130 microm with a first-generation microkeratome resulted in a high number of cut failures. Most patients were happy with the results despite a modest level of accuracy and glare.

LASEK (laser subepithelial keratomileusis)

Laser subepithelial keratomileusis (LASEK) is a relatively new refractive surgical technique that purportedly combines the advantages of laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Like LASIK, on the one hand, it employs a "flap" and consequently has the advantages of faster visual recovery, less postoperative pain, reduced stromal haze, and faster epithelial healing than PRK. Like PRK, on the other hand, because the procedure is performed on the anterior cornea, there are virtually no flap- or interface-related complications per se. It may thus be safer for patients who are at an inherently higher risk of developing flap complications, such as those with small palpebral fissures, deep-set eyes, corneal basement membrane dystrophy, and extremely steep or flat corneas. Furthermore, it conserves precious stroma in eyes with thin corneas or high myopia, which otherwise may not qualify for LASIK. It may also be more apropos for patients whose jobs or recreational activities put them at a higher risk of corneal trauma. In a very timely fashion, for reasons discussed below, LASEK may also prove to be superior to LASIK in customized ablations.

Flap and interface complications in LASIK

Flap complications using first-generation microkeratomes, such as the Automated Corneal Shaper, were reported in 2.5% (27 of 1,062 eyes). With modern microkeratomes, such as the Hansatome, keratotomy-related complications dropped to 0.16% (46 of 28,201 eyes). Postoperative flap complications, such as flap slippage, occurred in 1.42% (21 of 1,418 eyes), most of them during the first hour after surgery. Interface complications are a new diagnostic entity as the interface between flap and stroma presents an empty space where fluid or cells can accumulate. Diffuse lamellar keratitis usually occurs within the first postoperative days but may also develop later on, triggered, eg, by recurrent corneal erosion. Epithelial ingrowth is a rare complication caused rather by postoperative invasion than by intraoperative implantation, which suggests that the quality of the flap edge and its apposition are very important. Interface fluid is a rare but important phenomenon related to steroid-induced glaucoma but presenting with falsely low tonometry readings.