Primary Laser In Situ Keratomileusis Procedure Research Articles

Laser flap enhancement 5 to 9 years and 10 or more years after laser in situ keratomileusis: Safety and efficacy

To study the safety and efficacy of refractive enhancement by flap lifting 5 and 10 years after laser in situ keratomileusis (LASIK). Vissum Alicante, Spain. Retrospective case series. Eyes with a flap lift at least 5years after primary LASIK with a 3-month follow-up were evaluated. The primary outcome measures were safety and the complication rate. Moderate epithelial ingrowth was managed with Nd:YAG laser treatment. The primary LASIK procedure was myopic in 45 eyes, hyperopic in 22 eyes, and presbyopic in 3 eyes. The mean time from primary LASIK to the flap lift was 12.3years±3.45 (SD). In 57 eyes, the primary LASIK flap was created at least 10years before the enhancement. The mean pre-lift spherical equivalent was -1.29±1.23 diopters (D) in the myopia group and +0.65±1.72 D in the hyperopia group. Three months later, 88% of eyes and 74% of eyes, respectively, had an uncorrected distance visual acuity of 20/20 or better; 100% achieved at least 20/25. No eye lost 2 lines or more of corrected distance visual acuity. In the myopia group, the efficacy index was 0.94 and the safety index was 0.98 at 6months. Mild epithelial ingrowth developed in 31.43% of eyes and clinically significant epithelial ingrowth in 11.42% of eyes; 4.28% required a relift for severe epithelial ingrowth. Late flap lift for refractive enhancement 10years or more after LASIK provided good efficacy and safety with fast visual recovery. The rate of surgical intervention for significant postoperative epithelial ingrowth was low.

Nd:YAG laser for epithelial ingrowth after laser in situ keratomileusis.

To evaluate the efficacy of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK). Fifty-eight patients with epithelial ingrowth presented to Sohag refractive center, Sohag, Egypt, between January 2015 and March 2017. Only 41 patients (18 females and 23 males, mean age: 33.4years) involving 41 eyes were indicated for treatment by Nd:YAG laser as the rest of the eyes were only under observation. Patients with epithelial ingrowth were recognized at a mean of 6months after primary LASIK procedure (range: 2-16months). Four eyes had undergone previous LASIK enhancements. Four eyes had the epithelial ingrowth removed by flap lift and scrapping. The mean intensity of the spots used was 0.8mJ with variable number of shots depending on the size and density of the epithelial ingrowth area. Twenty-eight eyes showed complete regression after one session, while the rest necessitated 2-3 sessions for complete resolution. Mean follow-up period was 8months (range 5-12months). Epithelial ingrowth was treated successfully in all 41 eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6months with no complications reported. YAG laser is a simple, effective outpatient procedure for the management of epithelial ingrowth after LASIK.

Laser In Situ Keratomileusis Retreatment with Wavefront-Optimized Technique after Primary Wavefront-Guided LASIK: Proof of Concept

ABSTRACT Purpose: To assess the visual outcome and refractive error following wavefront (WF)- optimized laser in situ keratomileusis (LASIK) retreatment after previous WF-guided LASIK in myopic patients. Methods: A retrospective analysis of 19 eyes (14 patients) following WF-optimized LASIK retreatment after previous WF-guided LASIK that did not give desired refractive results was conducted. The primary LASIK procedures were performed using the Visx CustomVue™ laser with WF-guided technology. All of the subsequent retreatment LASIK procedures were performed with the Wavelight Allegretto™ Eye-Q 400 excimer laser using WF-optimized. Ophthalmic evaluations including uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), and manifest refraction spherical equivalent (MRSE) were performed at baseline and postoperatively at 1, 3, 6 months. Results: UCVA and BSCVA improved following retreatment from 0.27±0.18 and 0.0±0.05 to 0.01±0.05 and -0.03±0.05 respectively at 6 months (p<0.001 and p=0.38). The MRSE decreased from -0.5 D pre-retreatment to -0.2 D at 6 months postretreatment. The pre-retreatment total HOA was 0.48±0.21 (0.24 to 1.01μm) and did not show correlation with the visual outcomes postoperatively. No intra-operative or postoperative complications occurred. Conclusions: The results of this small case series with patients presenting low degrees of residual ametropia indicate that WF-optimized LASIK retreatment could be considered as an option after primary WFguided LASIK. Retreatment with WF-optimized LASIK is safe and the results are predictable.

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

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

Re-treatment after laser in situ keratomileusis for correction of myopia and myopic astigmatism

Aim:To evaluate the results of laser in situ keratomileusis (LASIK) re-treatment for under correction or regression after primary LASIK procedures for myopia and myopic astigmatism.Methods:A prospective evaluation of 360 consecutive...

Komplikationen nach Laser-in-Situ-Keratomileusis (LASIK): Ergebnisse einer Metaanalyse zu Inzidenzen und Folgekosten

Laser in situ Keratomileusis (LASIK) is considered to be safe and effective for the treatment of moderate myopia. Nevertheless, the treatment can result in complications, associated with additional costs for treatment of the latter and an associated reduction of the primary treatment's overall cost efficiency. To both identify clinically relevant LASIK-associated complications and to estimate their expectable incidence and treatment cost-profile, a quantitative meta-analysis of trial publications between 1995 - 2004 was implemented. Inclusion criteria were a minimum sample size of 25 eyes, a reported preoperative patient refraction between - 1 und - 14 dioptres and the documentation of an at least 6 months recall period. For each reported complication its "meta incidence" (point estimate and 95 % confidence interval) was estimated. Furthermore, for each complication a clinical pathway for its treatment was modelled assuming a worst case scenario; the treatment costs for this pathway were simulated. The resulting costs for the treatment of one complication were then averaged by the expectable incidence of the respective complication; the maximum "expectable" costs for the respective complication's treatment were then summed up to correct the overall LASIK direct costs. A total of 30 trial reports was included into the meta-analysis; in total, 21 clinically relevant complications were identified (31 % intraoperative complications, among which 19 % were microkeratome-associated, versus 69 % postoperative complications, among which 87 % were classified as long-term postoperative). The most frequent complication was "light sensations" with a meta incidence of 46 % (95 % confidence interval 42 - 50 %), the most cost intensive complications were those requiring clinical re-treatment (overall meta incidence 24 % and expectable cost increase of 449 euro per primary LASIK procedure). In summary the total direct costs of 2426 euro per eye for the initial LASIK procedure may be increased by a total of maximum 648.30 euro, according to a maximum "expectable" cost increase of 27 % per primary LASIK due to complications. At least the worst case scenario introduced into this investigation demonstrated an economically relevant order for the expectable LASIK complications and the associated additional costs for complication treatment.

Factors Influencing the Need for Enhancement After Laser in situ Keratomileusis

To confirm that enhancements after primary laser in situ keratomileusis (LASIK) are effective in dealing with residual refractive errors, and to determine if any variables prior to or during the primary LASIK procedure predisposed eyes to require subsequent enhancement. A retrospective study of eyes undergoing primary LASIK with the VISX S2 or S3 laser and Hansatome microkeratome between January 1, 2000 and January 1, 2002 was done. Of the 393 eyes of 207 patients, 58 eyes (14%) underwent enhancement within a 16-month window of the primary procedure. Statistical comparisons were made between enhanced (n = 37) and non-enhanced (n = 148) patients, and enhanced (n = 48) and non-enhanced (n = 303) eyes, treated for myopia only. In comparing the primary LASIK parameters of enhanced to non-enhanced eyes in myopic patients, no significant difference was found in right vs left eye, season of the primary treatment, preoperative astigmatism, pachymetry, or amount of attempted astigmatism correction. A multivariate logistic regression analysis revealed that male gender, patient age over 45 years, and a history of recent rigid contact lens use within 6 months of primary LASIK were significantly associated with the need for enhancement. Enhancements were an effective way of dealing with residual refractive errors after primary LASIK. Age greater than 45 years or a history of recent rigid contact lens use were significantly associated with the need for enhancement in patients with myopia or myopic astigmatism.

Flap and stromal bed thickness in laser in situ keratomileusis enhancement

Purpose: To evaluate whether flap thickness changes after the primary laser in situ keratomileusis (LASIK) procedure and to assess the accuracy of intraoperative pachymetry and ablation depth measurements in predicting stromal bed thickness before enhancement in eyes that have had primary myopic LASIK. Setting: Bascom Palmer Eye Institute, Miami, Florida, USA. Methods: This retrospective noncomparative interventional case series comprised 57 eyes of 42 patients who had LASIK enhancement between June 2001 and September 2002. Exclusion criteria included previous ocular surgery or complications during the first LASIK procedure. Only patients who had had LASIK and enhancement by the same surgeon at our institution and had intraoperative pachymetry readings for both procedures were included. The original flap was relifted in all enhancement procedures. Corneal thickness was routinely measured intraoperatively by ultrasound pachymetry. The age, eye, refraction, date of primary LASIK, central corneal thickness (CCT) and central stromal bed thickness at primary LASIK, depth of ablation, flap thickness (subtraction pachymetry), date of enhancement, CCT and central stromal bed thickness at enhancement, and flap thickness at enhancement were recorded. Results: Thirty-one eyes of 26 patients were myopic and 26 eyes of 16 patients were hyperopic before primary LASIK. The mean time between LASIK and enhancement was 218 days ± 115 (SD) (193 ± 88 days in myopic eyes and 248 ± 136 days in hyperopic eyes [ P = .068]). The flap tended to be thicker at enhancement than in the primary LASIK procedure by 9.3 ± 25.7 μm in myopic eyes ( P = .054) and 10.5 ± 16.6 μm in hyperopic eyes ( P = .004). A strong correlation was found between flap thickness in the first and second procedures in myopic and hyperopic eyes ( r = 0.6). In myopic eyes, the mean difference between the estimated stromal bed thickness after the first procedure (central bed thickness– ablation depth) and the stromal bed thickness measured directly at enhancement was not statistically significant (3 ± 29 μm; P = .54, paired t test). A strong correlation was found between the 2 measurements ( r = 0.8, P<.001). Another strong correlation was found in myopic eyes between the estimated corneal thickness after the primary LASIK and the corneal thickness measured at enhancement ( r = 0.81, P<.001). No correlation was found between the difference in flap thickness and the time to enhancement ( r = 0.09 in myopic eyes and r = 0.01 in hyperopic eyes). Conclusions: Flap thickness tended to be thicker at enhancement than at primary LASIK. Intraoperative pachymetry and ablation depth measurements proved to be precise tools to predict stromal bed thickness before enhancement in eyes that had had primary myopic LASIK. This information may help in planning LASIK enhancements.

Retained contact lens for more than 10 years in a laser in situ keratomileusis patient

A 49-year-old man with blurred vision in 1 eye and myopic regression had laser in situ keratomileusis (LASIK) in the right eye after having 20/20 uncorrected visual acuity for 2 years. At the conclusion of surgery, a poly(methyl methacrylate) contact lens that had been retained for more than 10 years was discovered in the upper fornix. Although the patient remained asymptomatic, reports of significant complications associated with retained contact lenses are numerous. In addition, retained contact lenses, lid lesions, and periocular masses can induce refractive and topographic changes after LASIK. The retained contact lens may have led to compression-induced changes in corneal curvature, resulting in the need for uniocular enhancement 2 years after the primary LASIK procedure.

Atopy: a patient-specific risk factor for diffuse lamellar keratitis

Objective To identify whether atopy is a patient-specific risk factor for the development of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK). Design Retrospective survey study. Participants Three hundred sixty consecutive patients who underwent same-day bilateral myopic astigmatic primary LASIK procedures during March 1, 2000, through July 31, 2000. Methods We collected data for 360 consecutive patients undergoing LASIK during a 4-month period. On preoperative medical history questionnaires, patients self-identified whether they were atopic. All patients also indicated whether they were taking antiallergy medications or were untreated for allergy. Main outcome measures The incidence of DLK after LASIK surgery. Results The risk of DLK in untreated atopic patients was much greater than the risk of DLK among nonatopics (odds ratio, 5.85; 95% confidence interval, 2.89–11.85; P = 0.001). However, the risk of DLK among atopic patients taking an oral systemic nonsedating histamine receptor 1 antagonist and among nonatopic patients did not differ significantly (odds ratio, 0.54; 95% confidence interval, 0.12–2.46; P = 0.43). Conclusions Atopy is a patient-specific risk factor for the development of DLK after primary bilateral LASIK for either myopia or myopic astigmatism. Atopic individuals benefit from preoperative treatment to minimize the incidence of DLK and the potential for visual loss.

Undersurface ablation of the flap for laser in situ keratomileusis retreatment

ObjectiveTo develop a novel technique, undersurface ablation of the flap (UAF), for laser in situ keratomileusis (LASIK) retreatment in eyes with insufficient posterior stroma. DesignNoncomparative, interventional case series. ParticipantsFrom 30 eyes examined, 25 eyes with a spherical equivalent residual refraction between −0.75 and −3.25 diopters (D) and astigmatism between 0.0 and −1.5 D were prospectively included in the study. In these eyes, calculated postenhancement flap thickness was >150 μm using micropachymetric optical coherence tomography (OCT), whereas with further ablation of the bed, posterior stromal thickness would have been <250 μm. Primary LASIK procedures had been performed with the Hansatome microkeratome. InterventionThe flap was lifted and the eye deviated downward, so that the corneal visual axis mark aligned with the laser beam. Mirror pattern ablations with an optical zone of 5 mm were performed on the flap stroma using either the Summit Apex Plus excimer laser or the Technolas Keracor 217 spot-scanning excimer laser. New axis orientation for toric ablations was calculated with the formula: β = 180° − α. Main outcome measuresRefraction, visual acuity, OCT pachymetry, tangential videokeratography, and patient satisfaction. ResultsThe average follow-up was 6.36 ± 2.64 months (range, 3–12 months). Mean preenhancement spherical equivalent (−2.05 ± 0.75 D) was reduced to −0.19 ± 0.38 D at the last visit (P = 0.001). Mean cylinder decreased from −0.48 ± 0.53 D before retreatment to −0.23 ± 0.28 D at the last follow-up (P = 0.003). Best-corrected visual acuity worsened by 1 line in two eyes (8%), and no eye lost 2 or more lines. Satisfactory globe stabilization and stromal smoothness during ablation were more difficult to achieve than with conventional LASIK enhancements. The average central flap thickness before UAF, 187 ± 13 μm, decreased to 164 ± 12 μm after 1 month (P = 0.001). No keratectasia developed. Finally, 92% of cases were satisfied with surgery compared with 48% before UAF retreatment (P = 0.001). ConclusionsUAF retreatment for low residual refractive errors after LASIK in eyes with sufficient flap stroma seems to be effective and may prevent future keratectasia.

Diffuse lamellar keratitis associated with epithelial defects after laser in situ keratomileusis

Purpose To describe the association between the presence of epithelial defects and the development of diffuse lamellar keratitis (DLK), “Sands of the Sahara” syndrome, following laser in situ keratomileusis (LASIK). Setting Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA. Methods In this retrospective study, the postoperative clinical course and surgical outcomes in 735 eyes of 358 consecutive patients who had myopic LASIK between December 1998 and August 1999 were reviewed. Of the 735 procedures, 680 were primary LASIK procedures and 55 were retreatments performed by lifting the existing flaps. The incidence and severity of DLK and the relationship of DLK to epithelial defects were tabulated. Results Diffuse lamellar keratitis developed in 9 of the 16 eyes that had postoperative epithelial defects. Seventeen eyes without epithelial defects also developed DLK. The presence of an epithelial defect increased an individual’s risk of developing DLK 24 times (95% confidence interval, 13 to 45). In 8 eyes, the inflammation resolved following treatment with intense topical corticosteroids. One eye had irrigation under the flap because of dense central inflammation; the final outcome was mild inferior corneal steepening. All eyes recovered preoperative best spectacle-corrected visual acuities. Conclusion Patients who have epithelial defects of any size following LASIK are at significantly increased risk of developing DLK.

Retreatment after laser in situ keratomileusis

Objective To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment for correcting residual myopia. Design Retrospective noncomparative case series. Participants and intervention Fifty-nine consecutive eyes (43 patients) underwent LASIK retreatment at 3 or 6 months after the primary LASIK procedure. Lifting the corneal flap and reablating the stromal bed with a VISX 20/20 excimer laser was the procedure used for LASIK enhancement. Main outcome measures The following parameters were studied before and after retreatment: visual acuity, refraction, videokeratography, applanation tonometry, and corneal thickness. Complications after LASIK enhancement also were evaluated. Follow-up was 12 months. Results Before retreatment, only 3.38% of eyes (2 of 59) had an uncorrected visual acuity of 0.5 (20/40) or better, and after retreatment, this percentage increased to 60% (30 of 50) at 6 months and 61.8% (34 of 55) at 12 months. After reoperation, mean best-corrected visual acuity improved by half a line over the values before retreatment. The preretreatment refraction of −2.92 ± 1.22 diopters (D) (mean ± standard deviation) decreased significantly to −0.44 ± 0.80 D at 6 months and to −0.61 ± 0.82 D at 12 months ( P < 0.001). In 82% of eyes (41 of 50) at 6 months and 81.8% (45 of 55) at 12 months, the spherical equivalent was within 1.00 D of emmetropia. There was a significant regression of effect (0.38 D) between 3 and 12 months ( P < 0.01). Postretreatment refraction was related to the original refraction before the primary LASIK, the preretreatment refraction, and the ablation diameter used. Although no vision-threatening complications were found, epithelial ingrowth and flap melting were more common after than before LASIK retreatment, with 31% of eyes at 12 months with epithelial ingrowth and 10.9% with flap melting. However, LASIK enhancement improved decentration and night-vision problems. Conclusions LASIK retreatment was an effective and predictable procedure for correcting residual myopia. Epithelial ingrowth and flap melting were more frequent after than before LASIK retreatment, whereas decentration and night-vision symptoms improved.

Results and complications of laser in situ keratomileusis by experienced surgeons.

To identify intraoperative and early postoperative adverse events and complications that may be encountered after the laser in-situ keratomileusis (LASIK) learning process. One hundred sixty-nine consecutive eyes of 108 patients who had LASIK by a surgeon experienced in LASIK were studied. All intraoperative and early postoperative adverse events and complications were noted. Patients were examined at 1 day and 1 to 3 months after surgery. Six baseline refractive groups were studied: high myopia with astigmatism (-10.25 to -17.50 D; 18 eyes), moderate myopia with astigmatism (-6.00 to -9.50 D; 31 eyes), low myopia with astigmatism (-0.75 to -5.87 D; 81 eyes), mixed astigmatism (-0.25 to +0.50 D; 6 eyes), low to moderate hyperopia with astigmatism (+1.00 to +3.75 D; 19 eyes), and high hyperopia with astigmatism (+4.25 to +7.37 D; 12 eyes). Seventy-eight percent (132 eyes) had a primary LASIK procedure; 22% (37 eyes) had LASIK after previous refractive surgery. Primary and secondary LASIK procedures were analyzed together. The Nidek EC-5000 or the Chiron PlanoScan excimer lasers were used. The most commonly observed adverse intraoperative events were minor corneal bleeding (3%) and thin flap (1%). The most commonly observed postoperative events were punctate epithelial keratopathy (6%) and small epithelial defect 1 day after surgery (5%). The most serious complication occurred in three eyes with preoperative high hyperopia (spherical equivalent refraction greater than +4.00 D) in which corneal topographic abnormalities resulted. At last examination, mean postoperative spherical equivalent refraction was less than +1.00 D in all groups. Spectacle-corrected visual acuity was 20/20 in 70 eyes (41%) and 20/25 or better in 119 eyes (70%). Loss of spectacle-corrected visual acuity of two or more lines occurred in five eyes (3%), three of which had preoperative high hyperopia with abnormal postoperative corneal topography. Our prospective study should help LASIK surgeons gauge their expectations of intraoperative and early postoperative complications. Surgeons should proceed cautiously when treating patients with high hyperopia, because a higher incidence of loss of spectacle-corrected visual acuity may be encountered postoperatively.