Pathogenesis and management of laser in situ keratomileusis flap buttonhole

Hydrogel sealant to prevent recurrent epithelial ingrowth in the setting of a LASIK flap buttonhole

Purpose

To report the first case of hydrogel sealant to prevent the recurrence of epithelial ingrowth in a LASIK flap buttonhole.

Observations

A 67-year-old female presented ten years after undergoing bilateral LASIK with diffuse lamellar keratitis and flap dislodgement after blunt trauma to the right eye. She was found to have epithelial ingrowth with diffuse debris and striae, so her flap was lifted and the epithelial ingrowth was removed. However, a central buttonhole was noted intraoperatively. Once all the epithelium was removed, the flap was repositioned and hydrogel sealant (ReSure, Ocular Therapeutix, Bedford, MA) was used to fill the buttonhole as well as seal down the edges of the flap. Sixteen months postoperatively, the patient's uncorrected visual acuity was 20/50-2 and there was no recurrence of the epithelial ingrowth at the edges of the buttonhole.

Conclusions and importance

Preventing the recurrence of epithelial ingrowth is a challenging situation, especially in the setting of a LASIK flap buttonhole. The use of hydrogel sealant in the buttonhole and around the edges of the flap may offer an elegant and effective solution.

Phototherapeutic Keratectomy: Science and Art

PURPOSE

To describe, with videos, the principles of excimer laser phototherapeutic keratectomy (PTK) for the treatment of corneal scars, corneal surface irregularity, and recurrent corneal erosions.

METHODS

Depending on the pathology in a treated cornea, the epithelium is removed either by transepithelial PTK ablation with the excimer laser or thorough scraping with a scalpel blade. Stromal PTK can be performed with or without photorefractive keratectomy (PRK), depending on the refractive status of both eyes. Residual surface irregularity is treated with masking-smoothing PTK. Typically, 0.02% mitomycin C treatment is applied for 30 seconds to corneas treated with PTK for scars and surface irregularity.

RESULTS

Transepithelial PTK with masking-smoothing typically improves corrected distance visual acuity in the eye even if the entire stromal opacity cannot be removed and can be used to debulk surface irregularity to facilitate subsequent therapeutic customized wavefront-guided or optical coherence tomography-guided PTK or PRK. PTK for recurrent erosion is performed after thorough mechanical epithelial debridement of redundant epithelial basement membrane (EBM) with a scalpel and should only include a dusting of excimer laser to remove residual EBM without inducing central irregular astigmatism or damaging limbal tissues. Meta-analyses are provided for PTK treatment for corneal scars, corneal dystrophies, and recurrent corneal erosions.

CONCLUSIONS

Excimer laser PTK is a highly effective treatment for superficial corneal scars, central corneal irregular astigmatism, and recurrent corneal erosions unresponsive to medical treatment or mechanical epithelial debridement alone. [J Refract Surg. 2017;33(3):203-210.].

One-step transepithelial photorefractive keratectomy with mitomycin C as an early treatment for LASIK flap buttonhole formation

PURPOSE

To assess the efficacy and safety of early one-step transepithelial photorefractive keratectomy (PRK) with mitomycin C as treatment for buttonhole formation during LASIK.

METHODS

Eight patients who developed a buttonhole during LASIK with mechanical or femtosecond flap creation underwent one-step transepithelial PRK a few days after the formation of the buttonhole. The re-treatment procedure was performed after complete epithelial healing and smooth epithelial fluorescein profile were ensured. Postoperative manifest refraction, uncorrected and corrected distance visual acuity, and haze formation were assessed during 6 months of follow-up.

RESULTS

Mean duration of the re-treatment procedure after buttonhole formation was 5 days (range: 4 to 7 days). Mean manifest refractive spherical equivalent and cylinder refraction were -0.05 ± 0.18 and -0.18 ± 0.22 diopters, respectively, at 6 months postoperatively. Uncorrected distance visual acuity was 20/20 in all patients after 3 months of follow-up. No haze formation was detected.

CONCLUSIONS

Early one-step transepithelial PRK with mitomycin C seems to be a safe and effective treatment for LASIK buttonhole complication.

Fibrin glue for prevention of recurrent epithelial ingrowth under a LASIK flap with a central buttonhole defect

A 61-year-old woman presented with a paracentral buttonhole flap defect associated with a linear tear, extensive epithelial ingrowth, and macrostriae in the right eye. A laser in situ keratomileusis enhancement had been performed 3 weeks earlier. The epithelial ingrowth was removed after careful lifting of the flap, and tissue adhesive was used postoperatively as a barrier to further ingrowth. Six months postoperatively, the patient's corrected distance visual acuity had improved to 20/20 and the slitlamp examination showed no evidence of recurrent epithelial ingrowth. This case presents a novel approach to the management of a buttonhole defect.

Outcomes of Retreatment after Aborted Laser In Situ Keratomileusis due to Flap Complications

Purpose:

To determine the refractive outcomes and complications of retreatment after aborted primary laser in situ keratomileusis (LASIK) due to flap complications.

Materials and Methods:

This retrospective study evaluated 50 retreated eyes that had flap complications during primary LASIK at the Eye Consultants Center in Riyadh, Saudi Arabia. Data were analyzed for patients with at least 3 months follow-up post retreatment.

Results:

Thirty-three eyes of 31 consecutive patients with 3 months follow-up or later post retreatment were included. The primary LASIK was aborted due to incomplete flaps in 22 eyes (66.7%), buttonhole flaps in 7 eyes (21.2%), free partial flaps in 3 eyes (9.1%), and a free complete flap in 1 eye (3.0%). Twenty-two eyes (66.7%) were retreated with LASIK, and 11 eyes (33.3%) were retreated with surface ablation. The mean spherical equivalent (SE) was –0.23 ± 0.72 D, the mean astigmatism was –0.65 ± 0.89 D, and the mean loss of the best corrected visual acuity (BCVA) was 0.78 lines at the final postoperative visit. At the last postoperative visit, 20/30 or better BCVA was achieved in 90.1% of eyes that underwent retreatment with LASIK and in 91% of eyes that were retreated with surface ablation. There was no statistical difference in postoperative SE between eyes retreated with LASIK and eyes retreated with surface ablation (P = 0.610). There was no statistical difference in postoperative BCVA between eyes retreated with LASIK and those retreated with surface ablation (P = 0.756). There were no intraoperative complications and no eyes required a second retreatment.

Conclusion:

Creation of a flap after a previous intraoperative flap complication was not associated with any complications. The refractive outcomes of retreatment with LASIK or surface ablation were comparable and reasonably favorable.

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.

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.

Traumatic Flap Dislocation 4 Years After LASIK Due to Air Bag Injury

PURPOSE

To report a patient who developed corneal flap dislocation following air bag injury 48 months after LASIK.

METHODS

Evaluation by slit-lamp microscopy and fluorescein angiography.

RESULTS

A 29-year-old man was treated after air bag injury that occurred 48 months after LASIK. Examination revealed corneal flap dislocation, with severe folds and flap edema. Preoperative visual acuity was finger counting at 1 m. Visual acuity was 20/400 24 hours after repositioning the corneal flap. Retinal angiography revealed Berlin macular edema, which was injected with periocular steroids. Five days after injection, visual acuity remained 20/400, but improved to 20/40 1 month after injection.

CONCLUSIONS

Significant trauma can dislocate a corneal flap many months after surgery.

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.

A Comparative Confocal Microscopy Analysis After LASIK With the IntraLase Femtosecond Laser vs Hansatome Microkeratome

PURPOSE

To evaluate and compare confocal microscopy findings between a femtosecond laser and a mechanical microkeratome.

METHODS

Eighteen eyes of nine patients underwent LASIK. Corneal flaps were created with the femtosecond laser in the right eyes and a mechanical microkeratome in the left eyes. The corneal flap interface was analyzed in all eyes with a confocal microscope at 1 week and 1 month postoperatively.

RESULTS

All eyes showed small reflective particles at the corneal flap interface. The mean number of reflective particles was not statistically significantly different at 1 week (P = .078) and 1 month (P = .28) using a femtosecond laser and a mechanical microkeratome.

CONCLUSIONS

Confocal microscopy findings at the corneal flap interface showed a similar number of particles using both systems.

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.

Hyperopic LASIK With Esiris/Schwind Technology

PURPOSE

To investigate the refractive and visual outcomes of hyperopic LASIK using Esiris/Schwind technology.

METHODS

This retrospective non-comparative observational study included 106 eyes (65 patients) operated with the Esiris/Schwind laser for hyperopia. Eyes were divided into two groups: group 1, < or = +3.99 diopters (D) and group 2, > or = +4.0 D (up to +7.0 D). Visual outcome for distance and near uncorrected (UCVA) and best spectacle-corrected visual acuities (BSCVA) (decimal values), cycloplegic refraction, keratometry (K), pachymetry, and complications were evaluated.

RESULTS

In group 1, mean UCVA was 0.4 +/- 0.1 preoperatively and 0.8 +/- 0.2 6 months postoperatively. Mean BSCVA was 0.9 +/- 0.1 preoperatively and 0.9 +/- 0.1 6 months postoperatively. Safety index was 1.1 and efficacy index was 0.97. Mean spherical equivalent refraction was +2.33 +/- 0.9 D preoperatively and +0.3 +/- 0.3 D 6 months postoperatively. Mean K reading was 43.7 +/- 1.1 D preoperatively and 45.0 +/- 1.6 D 6 months postoperatively. In group 2, mean UCVA was 0.3 +/- 0.1 preoperatively and 0.8 +/- 0.2 6 months postoperatively. Mean BSCVA was 0.9 +/- 0.1 preoperatively and 0.9 +/- 0.1 6 months postoperatively. Safety index was 0.98 and efficacy index was 0.92. Mean spherical equivalent refraction was +5.1 +/- 0.9 D preoperatively and +0.4 +/- 0.5 D 6 months postoperatively. Mean K reading was 43.1 +/- 1.6 D preoperatively and 46.0 +/- 1.4 D 6 months postoperatively. Forty-six (90.2%) of 51 eyes in group 1 and 47 (85.5%) of 55 eyes in group 2 were within +/- 0.5 D of emmetropia. At 6-month follow-up, 40 (78%) of 51 eyes in group 1 had UCVA of 20/20 compared to 41 (75%) of 51 eyes in group 2. One (2%) of 51 eyes in group 1 and 4 (7.3%) of 55 eyes in group 2 lost < or = 2 lines of BSCVA. No eye lost >2 lines of BSCVA.

CONCLUSIONS

Hyperopic LASIK with Esiris/Schwind technology is effective and safe in the correction of hyperopia up to + 7.0 D. Although a slight statistical significance was found for low hyperopia, visual and refractive results obtained in high hyperopia were encouraging.

Reproducibility of Flap Thickness With IntraLase FS and Moria LSK-1 and M2 Microkeratomes

PURPOSE

To compare flap thickness reproducibility of the femtosecond laser and two mechanical microkeratomes.

METHODS

Flap thickness for all eyes was measured as the difference between the preoperative (day of surgery) full corneal thickness and post-flap creation central stromal bed thickness using ultrasonic pachymetry. Flap thickness values produced by three different microkeratome systems were compared for accuracy and reproducibility.

RESULTS

For 99 flaps created using the IntraLase FS laser with an intended thickness of 110 microm, the mean achieved thickness was 119 +/- 12 microm (range: 82 to 149 microm). In 100 eyes treated with the Moria LSK-1 microkeratome with an intended flap thickness of 160 microm, the mean achieved thickness was 130 +/- 19 microm (range: 71 to 186 microm). In 135 eyes treated with the Moria M2 microkeratome with an intended flap thickness of 130 microm, mean thickness was 142 +/- 24 microm (range: 84 to 203 microm). The standard deviation and range of corneal flap thickness created with the IntraLase FS laser was significantly smaller than either mechanical microkeratome (P < .0001).

CONCLUSIONS

When compared to two commonly used mechanical microkeratomes, mean achieved flap thickness was more reproducible with the IntraLase FS laser, reducing the comparative risk of overly thick flaps.

Confocal Microscopy of Corneal Flap Microfolds After LASIK

PURPOSE

To describe the morphological characteristics of microfolds that appear at the corneal flap after LASIK, as seen under confocal microscopy.

METHODS

Twenty-one eyes that had undergone LASIK were examined, all within 3 weeks to 1 month after surgery. A central scan of the total corneal thickness was obtained by using confocal microscopy in vivo. Confocal images were captured and digitized. The longitudinal orientation (vertical, horizontal, and oblique) and morphological characteristics of the microfolds were described and recorded.

RESULTS

Six eyes had folds at the central corneal flap, visible as linear distortions in the confocal images: one fold had a vertical orientation, two were horizontal, and three were oblique. The folds were visible from the epithelial basal cell layer to the stromal portion of the flap and were deeper than Bowman's layer.

CONCLUSIONS

Confocal microscopy allowed visualization of microfolds after LASIK. With the appropriate software, it is possible to analyze the morphological characteristics of these folds. Flap microfolds after LASIK are deeper than Bowman's layer.

Amniotic membrane as a biologic pressure patch for treating epithelial ingrowth under a damaged laser in situ keratomileusis flap

We present 2 patients who had epithelial ingrowth after intraoperative laser in situ keratomileusis (LASIK) complications that created defects in the flap near the visual axis. As an adjuvant to removing the epithelium, an amniotic membrane patch was sutured tightly to the episclera so that it covered the entire cornea. The amniotic membrane overlay was left in place for about 1 week. There was no evidence of recurrent epithelial ingrowth after a minimum of 4 months. Use of an amniotic membrane overlay can be an effective adjuvant therapy to secure a LASIK flap when direct suturing would threaten the visual axis.

The effect of flap thickness on the visual and refractive outcome of myopic laser in situ keratomileusis

AIMS

To study the effect of flap thickness on the visual and refractive outcome of myopic laser in situkeratomileusis (LASIK) surgery.

METHODS

A total of 196 myopic eyes with spherical equivalent (SE) from -2.00 to -5.00 dioptres which underwent LASIK were studied retrospectively. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and manifest refraction were measured up to 6 months postoperatively. Logistic and linear regression analyses were used to examine the correlation of flap thickness to visual and refractive outcomes, postoperative complications and enhancement rate.

RESULTS

UCVA at 1 week and 1 month, but not at 1 day and at 6 months (P>0.05), were negatively correlated to flap thickness (P<0.05). BCVA was unrelated to flap thickness (P>0.05). At 1-month post-LASIK sphere and cylinder were not related to flap thickness (P>0.05), but spherical equivalent was negatively correlated (P<0.05). Significant negative correlations with the sphere and SE were noticed at 6 months for the eyes not requiring enhancements (P<0.05). Flap thickness had no significant relationship to postoperative complications (P>0.05) and no significant predictive value on the rate of enhancement procedures or the efficacy, safety and predictability indices (P>0.05).

CONCLUSIONS

In myopic LASIK thinner flaps are associated with faster visual recovery and less myopic SE, but the BCVA and the final UCVA are independent of flap thickness. Postoperative complications are unrelated to flap thickness. Flap thickness does not affect the efficacy, safety and predictability, or the rate of enhancement procedures.

Conductive Keratoplasty for the Correction of Residual Hyperopia After LASIK

PURPOSE

To report the 6-month results concerning efficacy, safety, predictability, and stability of conductive keratoplasty for the correction of residual hyperopia after corneal refractive surgery.

METHODS

A total of 35 eyes (26 patients) with residual hyperopia after corneal refractive surgery ranging between +1.00 to +4.75 diopters (D) of spherical equivalent refraction were enrolled in the study and underwent conductive keratoplasty following a modified nomogram.

RESULTS

Variables and data were available for all eyes at 6 months postoperatively. A total of 24 (69%) eyes had uncorrected visual acuity (UCVA) of > or = 20/40, and 10 (29%) eyes had UCVA of 20/20. Manifest refractive spherical equivalent was within +/- 0.50 D in 17 (49%) eyes and within +/- 1.00 D in 25 (71%) eyes in cases of previous hyperopic LASIK; the optical zone was significantly increased.

CONCLUSIONS

Using a modified nomogram, conductive keratoplasty for correction of residual hyperopia was effective, but predictability was not satisfactory and safety needs to be established.

Mitomycin-C assisted photorefractive keratectomy in the treatment of buttonholed laser in situ keratomileusis flaps associated with epithelial ingrowth

The prophylactic intraoperative use of mitomycin-C (MMC) to prevent haze and scarring after excimer laser surface ablation (phototherapeutic/photorefractive keratectomy [PTK/PRK]) in an eye with a previous laser in situ keratomileusis (LASIK) flap buttonhole with epithelial ingrowth is described. A well-centered buttonhole measuring 2.0 mm in diameter was cut within a thin LASIK flap in an amblyopic eye. Over the next 8 weeks, corneal haze and progressive epithelial ingrowth formed centrally. An early transepithelial PTK/PRK approach was chosen to manage the buttonhole together with the epithelial ingrowth and to treat ametropia before the onset of scarring. The approach included epithelial removal with PTK, application of MMC 0.02% for 1 minute, irrigation, a short waiting period to allow for diffusion, PRK correction of -4.0 diopters without nomogram adjustment, and bandage contact lens. A regimen of prednisolone acetate 1% and ofloxacin 0.03% 5 times a day for 1 week (steroid tapered) was prescribed. Epithelial ingrowth was removed successfully. Minimal haze formation was visible 2 weeks after the retreatment but did not reduce best spectacle-corrected visual acuity (BSCVA) and resolved within the next few weeks. After 6 weeks, uncorrected visual acuity was equal to BSCVA preoperatively (20/50). There was no evidence of recurrent epithelial ingrowth or central scarring after 24 months. Transepithelial PTK/PRK was effective in managing central epithelial ingrowth in a buttonholed LASIK flap. Prophylactic intraoperative use of MMC may reduce haze formation and corneal scarring in early treatments and may also prevent recurrent epithelial ingrowth. This approach may offer faster visual recovery and no risk for a repeated buttonhole creation compared with the widespread recutting a new flap after a couple of months. The optimal application time and concentration of MMC need to be established.

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.

Transepithelial phototherapeutic keratectomy/photorefractive keratectomy with adjunctive mitomycin-C for complicated LASIK flaps

PURPOSE

To evaluate the efficacy of transepithelial phototherapeutic keratectomy/photorefractive keratectomy (PTK/PRK) with prophylactic mitomycin-C for the treatment of refractive errors and maintenance of corneal clarity following flap complications in laser in situ keratomileusis (LASIK).

SETTING

Outpatient tertiary care center, Chicago, Illinois, USA.

METHODS

Ten eyes of 10 patients with LASIK flap complications had transepithelial PTK/PRK for correction of ametropia. Mitomycin-C 0.02% was applied to the stroma for 2 minutes following laser ablation. Postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractions, and slitlamp examinations were obtained.

RESULTS

Preoperatively, the mean UCVA was 20/400 (range 20/40 to counting fingers), the mean BSCVA was 20/28.5, and the spherical equivalent refractive errors ranged from +4.00 to -10.75 diopters (D). After the procedure, the mean UCVA was 20/28, the mean BSCVA was 20/21, and the spherical equivalent refractive errors ranged from +0.37 to -1.00 D. The mean follow-up ranged from 8 to 28 months. No patient experienced delayed reepithelialization, haze, or other signs of toxicity.

CONCLUSION

Mitomycin-C can be a useful adjunctive therapy for the prevention of haze when applying surface excimer laser therapy to a cornea following LASIK flap complications.

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.

LASIK for hyperopia, hyperopic astigmatism, and mixed astigmatism

OBJECTIVE

To describe LASIK for hyperopia, hyperopia with astigmatism, and mixed astigmatism and to examine the evidence to answer questions about the safety and efficacy of the procedure.

METHODS

A literature search conducted for the years 1968 to 2002 retrieved 118 citations. During review and preparation of this article, an additional 2 articles were included. The panel members selected 36 articles for the panel methodologist to review and rate according to the strength of evidence. A level I rating is assigned to properly conducted, well-designed, randomized clinical trials; a level II rating to well-designed cohort and case-control studies; and a level III rating to case series, case reports, and poorly designed prospective and retrospective studies.

RESULTS

This assessment describes 5 nonrandomized interventional trials (level II), 3 nonrandomized comparative trials (level III), and 20 noncomparative case series (level III). Additionally, 6 single-case reports (level III) were included because they reported relevant complications, and 2 theoretical analyses (level III) were also considered. This assessment does not compare studies because many variables such as range of hyperopia, follow-up periods, lasers, microkeratomes, techniques, and surgeon experience have not been controlled.

CONCLUSIONS

For low (<3 diopters [D]) to moderate (3-5 D) hyperopia, results from published studies (levels II and III evidence) have shown that LASIK is effective and predictable in achieving very good to excellent uncorrected visual acuity, achieving postoperative refractions within 1 D of emmetropia, and is safe in terms of minimal loss of best-corrected spectacle vision. Although there are fewer data for hyperopic astigmatism, the results available seem to mirror the data for low to moderate hyperopia (levels II and III evidence). The postoperative results for both uncorrected vision and safety are less compelling, as greater amounts of hyperopia are treated (>4 to 5 D). Utilizing hyperopic LASIK for the treatment of consecutive hyperopia and astigmatism is also effective, although the ability to reduce hyperopic astigmatism after radial keratotomy is limited. Although a variety of ablation profiles can be used to treat mixed astigmatism, very good visual results have been reported (levels II and III evidence). Serious adverse complications leading to permanent visual loss are possible but, fortunately, very rare. There are insufficient data to compare one laser system with another or one ablation profile with another.

Outcome of second surgery in LASIK cases aborted due to flap complications

PURPOSE

To describe the technique and timing of second refractive surgery after aborted laser in situ keratomileusis (LASIK) due to intraoperative flap complication and determine the final visual outcome.

SETTING

Outpatient ambulatory laser vision correction centers.

METHODS

This retrospective noncomparative case series included 16 patients (16 eyes) who had a second refractive surgery after initial LASIK surgery was aborted because of a flap complication. Charts were reviewed with attention to initial preoperative data, intraoperative details of the aborted LASIK, postoperative examination, possible causes of the flap complication, timing and technique of second refractive surgery, and final visual outcome.

RESULTS

Causes of the aborted LASIK were identified in 13 of 16 eyes (81.2%) and included eye squeezing (5 eyes), loss of suction or machine failure (5 eyes), steep corneas (2 eyes), and learning curve of the surgeon (1 eye). The mean time until the second surgery was 135 days (range 49 to 372 days). Repeat flaps were created deeper and larger than the initially attempted flaps when possible. No patient had a final uncorrected visual acuity (UCVA) worse than 20/30 after the second surgery. Two eyes (12.5%) lost 1 line of best spectacle-corrected visual acuity.

CONCLUSION

A planned delayed reoperation after sufficient corneal healing following an intraoperative flap complication can result in satisfactory recovery of UCVA.

PRK for epithelial ingrowth in buttonhole after LASIK

PURPOSE

To evaluate the efficacy of photorefractive keratectomy (PRK) in progressive central epithelial ingrowth after buttonholes after laser in situ keratomileusis (LASIK).

METHODS

Two eyes of two patients with progressive central epithelial ingrowth and fibrosis in flap buttonholes after LASIK underwent PRK 6 months following primary surgery.

RESULTS

Epithelial ingrowth was treated successfully in both eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6 months.

CONCLUSIONS

Photorefractive keratectomy is a useful modality in the treatment of central epithelial ingrowth in buttonholes following LASIK. As a single-step surgery, it offers both therapeutic and optical advantages by simultaneously clearing the corneal opacity and correcting the refractive error in selected cases.

Complications of Photorefractive Keratectomy and Laser in situ Keratomileusis

PURPOSE

To analyze the safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) with the Nidek EC-5000 excimer laser for surgery performed from Jan 1999 to Dec 2001.

METHODS

Retrospective study of excimer laser in 683 eyes: PRK was performed in 103 eyes and LASIK was performed in 580 eyes using the Nidek EC-5000 excimer laser and Moria Carriazo Barraquer microkeratome. We classified complications as intraoperative, early postoperative (30 days) and late postoperative complications. All patients were followed for at least 6 months.

RESULTS

There were 15 (2.19%) intraoperative microkeratome-related flap complications, 5 thin flaps (0.73%), 4 free caps (0.58%), 3 buttonholes (0.43%), and 3 small flaps (0.43%). The most frequent early postoperative complication was dry eye with pain in 42 eyes. There were 30 cases of microwrinkled flaps (4.39%), 14 cases of dislocated flaps or flap striae that necessitated lifting and irrigating the flap (2.04%), 8 interface epithelial ingrowth (1.17%), 4 interface debris (0.58%), 3 haze (0.43%), 3 glare (0.43%), 2 decentered ablations (0.29%), and 2 cases of toxic keratitis (0.29%). Late postoperative complications were 98 cases of spherical equivalent refraction more than or equal to 1.00 D (14.3%) with 6 months follow-up. Reoperation was necessary in 33 eyes (4.83%). Five eyes lost 1 or more lines of preoperative best spectacle-corrected visual acuity (0.73%), and 2 eyes had keratoconus (0.29%).

CONCLUSION

Refractive surgery with the Nidek EC-5000 excimer laser was safe, with few complications.

Laser-assisted subepithelial keratectomy for low to high myopia and astigmatism

PURPOSE

To evaluate the safety and efficacy of laser-assisted subepithelial keratectomy (LASEK) for the treatment of low to high myopia and astigmatism.

SETTING

Solo private practice, Mountain View, California, USA.

METHODS

Laser-assisted subepithelial keratectomy was performed in 146 eyes of 83 consecutive patients with myopia or myopic astigmatism using a VISX Star S2 excimer laser (72 eyes) or a Nidek EC-5000 excimer laser (74 eyes). The mean preoperative myopic spherical equivalent was -5.32 diopters (D) (range -1.25 to -14.38 D). Data were collected prospectively with a follow-up of 1 to 12 months. Outcome measurements included uncorrected visual acuity (UCVA), manifest refraction, best spectacle-corrected visual acuity (BSCVA), corneal haze, and complications.

RESULTS

After 6 and 12 months, no eye lost 2 or more lines of BSCVA. After 6 months, the UCVA was 20/20 in 57% of eyes and 20/40 or better in 96%. After 12 months, it was 20/20 in 56% of eyes and 20/40 or better in 96%. No eye developed corneal haze that affected visual acuity. There were no serious or vision-threatening complications.

CONCLUSIONS

Laser-assisted subepithelial keratectomy was safe and effective in treating a wide range of myopia and astigmatism. The potential advantages of LASEK over laser in situ keratomileusis (LASIK) include the elimination of stromal flap complications and greater choice in patient selection. The disadvantages include varying degrees of pain for 2 days and blurry vision for several days postoperatively.

Flap Measurements With the Hansatome Microkeratome

PURPOSE

To evaluate flap thickness, flap diameter, and hinge length during laser in situ keratomileusis (LASIK) and to correlate these measurements with preoperative keratometric power, central corneal thickness, and patient refraction, gender, and age.

METHODS

In this prospective study of 50 eyes of 28 patients (mean age 31 +/- 6.6 yr; range, 24 to 43 yr) results of LASIK for myopia were analyzed (mean spherical equivalent refraction of -7.16 +/- 1.69 D; range, -2.75 to -13.50 D). Corneal flaps were created using the Hansatome microkeratome (Baush & Lomb Surgical) with a 160-microm plate and a 9.5-mm suction ring. Corneal thickness was evaluated using an ultrasonic 50-MHz pachymeter (Sonogage Corneo Gage Plus) and the mean keratometric power was measured with a Corneal Analysis System videokeratographic unit (EyeSys). Data were analyzed using t-test, Pearson product moment correlation coefficient, and Spearman's rho non-parametric correlation coefficients.

RESULTS

Mean corneal flap thickness was 142.6 +/- 20.8 microm (range, 107 to 177 microm), mean flap diameter was 9.9 +/- 0.3 mm (range, 9.2 to 10.5 mm), and mean hinge length was 6.2 +/- 0.4 mm (range, 5.2 to 7 mm). Statistically significant correlations (P<.05) were found between mean keratometric power and flap hinge length, mean keratometric power and flap diameter, preoperative spherical equivalent refraction and flap diameter, corneal thickness and flap hinge length, as well as patient age and corneal thickness.

CONCLUSIONS

The Hansatome microkeratome was an effective and safe instrument in the creation of corneal flaps for LASIK. Consideration of preoperative keratometric power and corneal thickness may help to reduce or avoid complications.

Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy: a report by the American Academy of Ophthalmology

OBJECTIVE

This document describes laser in situ keratomileusis (LASIK) for myopia and astigmatism and examines the evidence to answer key questions about the efficacy and safety of the procedure.

METHODS

A literature search conducted for the years 1968 to 2000 retrieved 486 citations and an update search conducted in June 2001 yielded an additional 243 articles. The panel members reviewed 160 of these articles and selected 47 for the panel methodologist to review and rate according to the strength of evidence. A Level I rating is assigned to properly conducted, well-designed, randomized clinical trials; a Level II rating is assigned to well-designed cohort and case-control studies; and a Level III rating is assigned to case series and poorly designed prospective and retrospective studies, including case-control studies.

RESULTS

The assessment describes randomized controlled trials published in 1997 or later (Level I evidence) and more recent comparative and noncomparative case series (Level II and Level III evidence), focusing on results for safety and effectiveness. It is difficult to extrapolate results from these studies that are comparable to current practices with the most recent generation lasers because of the rapid evolution of LASIK technology and techniques. It is also difficult to compare studies because of variations in the range of preoperative myopia, follow-up periods, lasers, nomograms, microkeratomes and techniques, the time frame of the study, and the investigators' experience.

CONCLUSIONS

For low to moderate myopia, results from studies in the literature have shown that LASIK is effective and predictable in terms of obtaining very good to excellent uncorrected visual acuity and that it is safe in terms of minimal loss of visual acuity. For moderate to high myopia (>6.0 D), the results are more variable, given the wide range of preoperative myopia. The results are similar for treated eyes with mild to moderate degrees of astigmatism (<2.0 D). Serious adverse complications leading to significant permanent visual loss such as infections and corneal ectasia probably occur rarely in LASIK procedures; however, side effects such as dry eyes, night time starbursts, and reduced contrast sensitivity occur relatively frequently. There were insufficient data in prospective, comparative trials to describe the relative advantages and disadvantages of different lasers or nomograms.

Risk Factors for Insufficient Fixation of Microkeratome During Laser in situ Keratomileusis

PURPOSE

To investigate the potential risk factors leading to insufficient fixation of a microkeratome during laser in situ keratomileusis (LASIK), especially in Asian eyes.

METHODS

We performed a retrospective analysis of 1809 eyes of 972 patients that underwent LASIK. Profiles of patients (age, sex, past medical history, width of palpebral fissure, corneal power, and postoperative clinical course) whose operations were discontinued due to insufficient fixation were compared to all LASIK patients.

RESULTS

Insufficient fixation was observed in 18 eyes of 16 patients. Those patients were significantly younger (26.1 +/- 5.5 yr) compared to all patients (32.3 +/- 8.6 yr). Mean keratometric power was 42.40 +/- 1.37 D in patients with insufficient fixation and 43.60 +/- 1.40 D in all patients (P < .001). Maximum width of palpebral fissure with eyes wide open was 0.96 +/- 0.20 mm in patients with insufficient fixation, and 1.10 +/- 0.19 mm in all patients (P = .0015). These patients subsequently underwent LASIK utilizing combinations of cooling, frequent corticosteroid instillation for several hours, and lateral canthotomy.

CONCLUSION

Narrow palpebral fissures commonly found in Asian populations might be a risk factor for insufficient fixation of a microkeratome in LASIK, especially in young patients with flat corneas.

Corneal ectasia induced by laser in situ keratomileusis

PURPOSE

To identify factors that can lead to corneal ectasia after laser in situ keratomileusis (LASIK).

SETTING

University refractive surgery center.

METHODS

In this retrospective study, the charts of all patients (2873 eyes) who had LASIK between May 1995 and November 1999 were reviewed. Fourteen patients (19 eyes, 0.66%) developed post-LASIK ectasia. The mean follow-up was 16.32 months (range 6 to 42 months).

RESULTS

No patient with an attempted correction less than 8.00 diopters or a residual corneal bed thickness greater than 325 microm experienced post-LASIK ectasia. There was a statistically significant positive correlation between corneal residual bed thickness and increasing patient age.

CONCLUSION

Despite the limitations of the small sample size, the study's results suggest that parameters besides residual corneal bed thickness (eg, age, attempted correction) may have to be considered to avoid post-LASIK ectasia.

LASIK complications: etiology, management, and prevention

Laser in situ keratomileusis (LASIK) is a rapidly evolving ophthalmic surgical procedure. Several anatomic and refractive complications have been identified. Anatomic complications include corneal flap abnormalities, epithelial ingrowth, and corneal ectasia. Refractive complications include unexpected refractive outcomes, irregular astigmatism, decentration, visual aberrations, and loss of vision. Infectious keratitis, dry eyes, and diffuse lamellar keratitis may also occur following LASIK. By examining the etiology, management, and prevention of these complications, the refractive surgeon may be able to improve visual outcomes and prevent vision-threatening problems. Reporting outcomes and mishaps of LASIK surgery will help refine our approach to the management of emerging complications.

In vivo confocal microscopy of corneal epithelial ingrowth through a laser in situ keratomileusis flap buttonhole

We report a case of epithelial ingrowth through a buttonhole 6 months after laser in situ keratomileusis. Elevation topography showed irregular astigmatism and an unreliable pachymetric map. In vivo confocal microscopy showed an epithelial basal cell mosaic with prominent borders and distinct nuclei. No corneal nerves were identified in any image. Cells in the anterior stroma possessed bright, reflective nuclei and appeared to form clusters. The interface between the stromal bed and the flap had formation of nests of fibrotic tissue and epithelial cells.