Results of phototherapeutic keratectomy in the management of flap striae after LASIK

OBJECTIVE: To evaluate the efficacy of phototherapeutic keratectomy (PTK) in reducing or resolving visually significant surface irregularities resulting from flap striae after LASIK. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Twenty-three eyes of 22 patients with flap striae after LASIK and reduced best-corrected visual acuity or visual symptoms that resolved with diagnostic contact lens fitting treated between January 2001 and April 2002 with at least 1 month of follow-up. The mean follow-up interval was 134 days (range, 30-354 days). INTERVENTION: Transepithelial PTK. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), resolution or reduction of preoperative symptoms, corneal haze, and best spectacle-corrected visual acuity (BSCVA). RESULTS: Mean BSCVA and UCVA improved significantly from 20/32 and 20/48 to 20/22 and 20/33 (P<0.0001 and P = 0.027), respectively, after PTK. There was a significant mean hyperopic shift of 0.88 diopters (D; P = 0.002, range, -1.38 to +3.88 D). Fourteen eyes (61%) were clinically clear, 6 eyes (23%) had trace haze, and 3 eyes (16%) had 1+ haze at the last follow-up visit. Mean spherical equivalent refractive error before LASIK was -7.23 D (range, -2.88 to -13.55 D). Twenty-two of 23 eyes had significant qualitative resolution or reduction of preoperative visual symptoms. CONCLUSIONS: In cases of visually significant LASIK flap striae, PTK is effective in improving best-corrected visual acuity and reducing visual symptoms. High myopia may be a risk factor for development of visually significant microstriae. Development of anterior stromal haze did not exceed 1+ density and was not correlated to either the number of laser pulses or the length of the follow-up period.     

Very high-frequency ultrasound corneal analysis identifies anatomic correlates of optical complications of lamellar refractive surgery: anatomic diagnosis in lamellar surgery

OBJECTIVE: To examine the utility of very high-frequency (VHF) ultrasound scanning in determining the anatomic changes and correlates of optical complications in lamellar refractive surgery. STUDY DESIGN: Case series. PARTICIPANTS: Cases analyzed included marked asymmetric astigmatism postautomated lamellar keratoplasty (ALK), image ghosting despite normal videokeratography post-ALK, uncomplicated myopic laser in situ keratomileusis (LASIK), and hyperopic LASIK with regression. METHODS: A prototype VHF ultrasound scanner (50 MHz) was used to obtain sequences of parallel B-scans of the cornea. Digital signal processing techniques were used to measure epithelial, stromal, and flap thickness values in a grid encompassing the central 4 to 5 mm of the cornea, enabling pachymetric mapping of each layer with 2-micron precision. MAIN OUTCOME MEASURE: The appearance of the corneas in VHF ultrasound images and thickness values of individual corneal layers determined from VHF ultrasound data. RESULTS: VHF ultrasound resolved the epithelial, stromal cap, or flap and residual stromal layers 1 year after lamellar surgery. Asymmetric stromal tissue removal was differentiated from stromal cap irregularity. Epithelium acted to compensate for asymmetry of the stromal surface about the visual axis and for localized surface irregularities. Irregularities in the epithelial-stromal interface accounted for image ghosting present despite apparently normal videokeratography. Epithelial thickening was shown after uncomplicated myopic LASIK. Hyperopic LASIK demonstrated relative epithelial thickening localized to the region of ablation accounting for refractive regression. CONCLUSIONS: VHF ultrasound shows promise as a sensitive method of determining the anatomic correlates of optical complications in lamellar refractive surgery.     

Retreatment after laser in situ keratomileusis

ObjectiveTo evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment for correcting residual myopia.DesignRetrospective noncomparative case series.Participants and interventionFifty-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 measuresThe 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.ResultsBefore 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.ConclusionsLASIK 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.     

Partial flap during laser in situ keratomileusis: role of smaller diameter corneal flap of original thickness

PURPOSE: To report results of smaller diameter corneal flap of original thickness in the management of partial flap during laser in situ keratomileusis (LASIK). METHODS: Retrospective review of the case records of three patients (3 eyes) who had a partial corneal flap during LASIK. RESULTS: Retreatment was performed using an 8.5-mm-diameter corneal flap, which was smaller than the original partial flap of 9.5-mm diameter. The recut depth was maintained as the original cut depth of 160 microm. No intraoperative or postoperative complications were noted. At follow-up 4 weeks later, two patients had an uncorrected visual acuity of 20/20. One patient had uncorrected visual acuity of 20/40 that improved to preoperative best spectacle-corrected visual acuity of 20/30 with a correction of +0.50 -1.25 x 170 degrees. CONCLUSION: A smaller diameter corneal flap of original thickness can be used for retreatment of partial flap during LASIK. A thicker posterior stromal bed after laser ablation may be retained with this technique, compared to retreatment using a corneal flap of greater thickness.     

Very high-frequency digital ultrasound evaluation of topography-wavefront-guided repair after radial keratotomy

We report a topography-wavefront-guided repair procedure in a patient with a decentered optical zone and significant higher-order aberrations (HOAs) following radial keratotomy 14 years previously. The CRS-Master custom ablation software was used to generate a topography-wavefront-guided ablation profile based on Atlas front corneal surface topography data, and the MEL 80 excimer laser was used to treat the patient. Very high-frequency digital ultrasound scanning (Artemis) was performed before and after surgery to measure epithelial and stromal thickness changes to evaluate the anatomical congruity of the planned and achieved irregular ablation. Nine months postoperatively, the optical zone centration was topographically improved and HOAs were significantly lower, with a 90% reduction in spherical aberration. The stromal thickness change map demonstrated that the profile of stromal tissue removed matched the irregular ablation profile. However, the measured stromal thickness change at the maximum point was 33% higher than the predicted ablation depth. The epithelial thickness change measured in this case indicates that topography-guided treatments could be improved by taking epithelial thickness changes into account.     

Management of severe flap wrinkling or dislodgment after laser in situ keratomileusis

PURPOSE: To review the management and results of cases with severe flap wrinkling or dislodgment after laser in situ keratomileusis (LASIK). SETTING: University Eye Center, Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong. METHODS: Four patients with severe flap wrinkling or dislodgment after LASIK are described. Surgical repositioning of the flap was performed in all cases. Flap status, refractive changes, and final uncorrected and best corrected visual acuities were used to evaluate the outcome of flap repositioning. RESULTS: Flap repositioning required suturing in 2 patients, 1 of whom developed severe epithelial ingrowth with melting of the corneal flap and stromal bed and eventually required flap removal. The stromal inflammation resolved, and the corneal surface re-epithelialized after flap excision. In 2 other patients, wedge-shaped tissue excision (1.0 x 1.5 mm) from the superior portion of the corneal flap was necessary to allow better flap realignment. In 1 of these patients, the corneal flap was eventually converted to a free cap to correct residual wrinkling. At a mean follow-up of 15 months, the postoperative uncorrected visual acuity ranged from 20/20 to 20/60, and the best spectacle-corrected visual acuity (BSCVA) was 20/30 or better in all patients. In 1 patient, BSCVA decreased by 1 line. CONCLUSIONS: Flap dislodgment and wrinkling are serious postoperative complications of LASIK. Early recognition of these complications and prompt surgical management are crucial to achieve a successful surgical and visual outcome.     

Epithelial scraping for corneal epithelial ingrowth after laser in situ keratomileusis

BACKGROUND: Laser in situ keratomileusis (LASIK) is an effective method for correcting a wide range of myopia. However, complications sometimes occur. We report here a case treated with epithelial scraping two years and 4 months after surgery for epithelial ingrowth in the central cornea after LASIK. CASE: A 32 year-old woman who had undergone LASIK one year and 4 months before visited our hospital because of visual loss. At the first examination in our clinic, her best-corrected visual acuity was 20/60 in the right eye and 20/15 in the left eye. Epithelial ingrowth was observed in both eyes, but in the right eye, the epithelial ingrowth had reached the central cornea leading to the visual loss. The increased corneal stromal opacity decreased the visual acuity to 20/400. The patient decided to undergo epithelial scraping. The corneal flap was dissected again and epithelial scraping was performed on the stromal bed and back of the corneal flap. The visual acuity was improved from 20/400 to 20/40. However, the stromal opacity and the corneal astigmatism still remained. CONCLUSION: This case suggests that epithelial scraping should be performed immediately when ingrowing epithelium after LASIK begins to invade the central cornea.     

Arc-scanning very high-frequency digital ultrasound for 3D pachymetric mapping of the corneal epithelium and stroma in laser in situ keratomileusis

PURPOSE: To test and demonstrate measurement precision, imaging resolution, 3D thickness mapping, and clinical utility of a new prototype 3D very high-frequency (VHF) (50 MHz) digital ultrasound scanning system for corneal epithelium, flap, and residual stromal thickness after laser in situ keratomileusis (LASIK). METHODS: VHF ultrasonic 3D data was acquired by arc-motion, meridional scanning within a 10-mm zone. Digital signal processing techniques provided high-resolution B-scan imaging, and I-scan traces for high-precision pachymetry in 4 eyes. Thickness maps of individual corneal layers were constructed. Reproducibility of epithelial, flap, and full corneal pachymetry was assessed for single-point and 3D thickness mapping by repeated measures. Thickness mapping of the epithelium, stroma, flap, and full cornea were determined before and after LASIK. Preoperative to postoperative difference maps for epithelium, flap, and stroma were produced to demonstrate anatomical changes in the thickness profile of each layer. RESULTS: Surface localization precision was 0.87 microm. Central reproducibility for single-point pachymetry of epithelium was 0.61 microm; flap, 1.14 microm; and full cornea, 0.74 microm. Reproducibility for central pachymetry on 3D thickness mapping was 0.5 microm for epithelium and 1.5-microm for full cornea. B-scans and 3D thickness maps after LASIK demonstrated resolution of epithelial, stromal component of the flap, and residual stromal layers. Large epithelial profile changes were demonstrated after LASIK. Topographic variability of flap thickness and residual stromal thickness were significant. CONCLUSIONS: VHF digital ultrasound arc-B scanning provides high-resolution imaging and high-precision three-dimensional thickness mapping of corneal layers, enabling accurate anatomical evaluation of the changes induced in the cornea by LASIK.     

Comparison of residual stromal bed and flap thickness in primary and repeat laser in situ keratomileusis in myopic patients

PURPOSE: To compare the change in residual stromal thickness and flap thickness between primary laser in situ keratomileusis (LASIK) and repeat LASIK in myopic patients. SETTING: Melbourne Excimer Laser Group, East Melbourne, Australia. METHODS: This retrospective nonrandomized comparative trial comprised 46 eyes of 34 patients who had repeat LASIK. The thickness of the residual stromal bed was calculated by subtracting the calculated stromal ablation from pachymetry of the stromal bed after cutting the flap in primary treatment and directly measuring during retreatment. The thickness of the LASIK flap in primary and repeat LASIK was calculated by subtracting the central pachymetry of the stromal bed after creating the flap from pachymetry before cutting and lifting the flap, respectively. The main outcome measures were comparison of the residual stromal bed and flap thickness between the primary treatment and the retreatment. RESULTS: The mean thickness of the calculated residual stromal bed after primary treatment was 329.8 microm +/- 40.8 (SD), and the mean measured residual stromal bed at retreatment was 317.3 +/- 42.8 microm. The mean difference in residual stromal bed thickness was 12.5 +/- 13.0 microm (P<.001). Sixteen eyes (34.7%) had a decrease in bed thickness between 11 microm and 20 microm. The mean flap thickness during primary LASIK and repeat LASIK was 145.2 +/- 17.1 microm and 169 +/- 18.3 microm, respectively. The mean interval between primary treatment and retreatment was 7.4 +/- 4.1 months. The mean change in flap thickness was 23.8 +/- 15.2 microm (P<.001). Fifteen eyes (32%) had an increase in flap thickness between 11 microm and 20 microm. There was a negative correlation between refractive error before primary treatment and the difference in flap thickness. No correlation was found between the difference in flap thickness and the interval between the primary treatment and the repeat treatment. CONCLUSIONS: Intraoperative pachymetry of the stromal bed during retreatment is strongly recommended as the residual stromal bed and flap thickness changes between primary and retreatment. There is a tendency for the measured stromal bed at retreatment to be thinner than the calculated stromal bed and for the flap to be thicker than previously measured.     

Aspergillus fumigatus keratitis following laser in situ keratomileusis

A 31-year-old woman developed pain, decreased vision, and a corneal flap infiltrate 4 days following laser in situ keratomileusis (LASIK). Treatment with topical antibiotic agents did not improve the symptoms. Approximately 2 weeks after surgery, the patient was referred to Stanford University, with 20/400 visual acuity in the left eye and a stromal infiltrate posterior to the flap. Cultures demonstrated Aspergillus fumigatus sensitive to voriconazole. The corneal ulcer progressed despite aggressive antifungal treatment, requiring amputation of the corneal flap and daily debridement. The infiltrate resolved in response to topical voriconazole, natamycin, and oral voriconazole. Aspergillus fumigatus keratitis is a rare but serious complication of LASIK surgery. The infection was successfully treated with flap amputation and daily debridement in addition to antifungal therapy.     

LASIK术中用飞秒激光制瓣的临床观察

目的 观察LASIK术中使用飞秒激光制作角膜瓣的临床效果及分析飞秒激光仪制作不理想瓣的处理方法.方法 将2402例(4697眼)应用飞秒激光制作角膜瓣后行LASIK的近视患者.根据术前设计角膜瓣厚度分成90 μm的255例(479只眼),110 μm 2091例(4138只眼),140 μm 56例(80只眼),术后1周使用傅立叶光学相干断层扫描测量角膜瓣的实际厚度进行分析.结果 术后1周实际角膜瓣厚度:90 μm角膜瓣平均厚度[90.54±6.06(82～ 101 )]μm,110 μm角膜瓣平均厚度[109.79±7.62(103～116)]μm,140μm角膜瓣平均厚度[138.85±5.68(129～147)]μm,术后实际角膜瓣厚度与术前预先设计角膜瓣厚度差异无统计学意义(P＞0.01).在制瓣过程中,出现5种不理想的角膜瓣问题:角膜切削基质面中心颗粒大、角膜切削面基质面有条纹、角膜切削基质面条形粘连、角膜切削基质面中心粘连、飞秒激光切削角膜后角结膜结合处出现气泡,并总结其处理方法.结论 飞秒激光制作角膜瓣行LASIK,切削精确、安全性高,在一定程度上可抑制手术造成的像差、提高对比敏感度.     

CustomCornea wavefront retreatment after conventional laser in situ keratomileusis

PURPOSE: To evaluate the safety and efficacy of performing laser in situ keratomileusis (LASIK) retreatment using the Alcon CustomCornea system in patients who had prior myopic LASIK using conventional (nonwavefront) software. SETTING: Private practice ophthalmology clinic, St. Paul, Minnesota, USA. METHODS: In this prospective interventional trial, consecutive patients having CustomCornea retreatment following conventional LASIK were evaluated. Main outcome measures were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive error, and higher-order aberrations (HOAs). RESULTS: Fourteen eyes of 10 patients were evaluated, with a mean follow-up of 5.3 months (range 6.2 to 15.4 months). Mean UCVA improved from 20/50 (logMAR) to 20/26 (P<.001). Mean spherical equivalent changed from -1.45 diopters (D) to +0.52 (P<.00001). Total aberrations, HOAs, defocus, and spherical aberration improved significantly. No eye lost a line of BCVA; 4 eyes (28.6%) gained 1 line, and 1 eye (7.1%) gained 2 lines. Ten eyes (71.4%) were within 0.5 D of emmetropia. Four eyes were overcorrected by 1.00 to 2.00 D. Risk factors for overcorrection included increased HOAs, higher spherical aberration, and not using the surgeon's offset at the time of surgery. CONCLUSIONS: Wavefront retreatment following conventional LASIK is safe and effective. Care must be taken when treating patients with higher amounts of total aberration, especially spherical aberration. Refractive results are closer to emmetropia when the surgeon's offset is used.     

Late-onset traumatic dislocation with central tissue loss of laser in situ keratomileusis flap

PURPOSE: We report the occurrence and outcome of a severe late-onset traumatic dislocation of a laser in situ keratomileusis (LASIK) flap with loss of central flap tissue. METHODS: Case report. RESULTS: A 40-year-old woman underwent uncomplicated bilateral LASIK surgery, followed 5 years later by an enhancement procedure in both eyes. Ocular trauma with a power sander occurred 6 years after LASIK and 1 year after the enhancement procedure. The flap was found to have an almost complete tear from the nasal hinge and a central tissue defect. After irrigating, repositioning, and stabilizing the flap with 2 nylon sutures, a bandage contact lens was placed. The patient was treated with topical antibiotic and steroid drops. Stage 2 diffuse lamellar keratitis developed, which responded to topical treatment. Ten weeks after injury, the patient regained an uncorrected visual acuity of 20/20-1. CONCLUSION: Late-onset trauma to the LASIK flap can result in flap dehiscence and tissue loss. Prompt and appropriate management can lead to an excellent visual outcome even in severely traumatized dislocated LASIK flaps.     

Epi-LASIK after amputation of a LASIK flap

PURPOSE: To demonstrate the feasibility of performing epi-LASIK after amputation of a LASIK flap. METHODS: Three months following complicated primary LASIK and immediate flap amputation, a Lasitome microkeratome (Gebauer, Neuhausen, Germany), equipped with an epi-head and -blade, was used to perform an epi-LASIK surface ablation. RESULTS: Despite uneven stromal contour at the site of the original hinge after amputation of the LASIK flap, the microkeratome passage was uneventful, resulting in a regular epithelial flap. Laser ablation was performed and the epithelial flap was repositioned. CONCLUSIONS: Epi-LASIK was completed with no intraoperative complication in the presence of an irregular stromal surface after amputation of a LASIK flap. This procedure may extend our options in the management of LASIK flap-related complications.     

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 microm in myopic eyes (P = .054) and 10.5 +/- 16.6 microm 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 microm; 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.     

Reoperations after myopic laser in situ keratomileusis

PURPOSE: To evaluate the results after enhancement of myopic laser in situ keratomileusis (LASIK) using the VISX Star excimer laser. SETTING: The Buzard Eye Institute, Las Vegas, Nevada, USA. METHODS: In this prospective study, 52 eyes of 40 patients had LASIK enhancement. The existing flap was lifted and the excimer laser treatment reapplied for the residual refractive error. The VISX Star excimer laser was used for the primary LASIK and the enhancement procedure. Retreatments for undercorrection, regression, and overcorrection were performed after 6 weeks and up to 40 weeks after the primary LASIK. Follow-up was 96% at 1 month, 67% at 6 months, and 71% at 12 months. RESULTS: Mean pre-enhancement spherical equivalent was -0.77 diopters (D) +/- 0.94 (SD) and mean uncorrected visual acuity (UCVA), 20/60. One year after the enhancement, mean spherical equivalent was -0.13 +/- 0.33 D, and mean UCVA was 20/25. Refraction remained stable during the 1 year follow-up, with no treatment required. After the enhancement, all patients had a UCVA of 20/40 or better. At 1 year, 3% of patients had lost 1 line of best corrected visual acuity and 32% had gained 1 line. No epithelial ingrowth was noted. CONCLUSION: Retreatment for LASIK beginning 6 weeks after the initial procedure proved to be effective with minimal complications and good results. The technique to raise and reposition the flap appeared safe, and complications were few.     

Relationship between preoperative aberrations and postoperative refractive error in enhancement of previous laser in situ keratomileusis with the LADARVision system

PURPOSE: To identify factors leading to inaccuracy of spherical correction in wavefront-guided enhancement treatments. SETTING: Department of Ophthalmology, University of California, Irvine, California, USA. METHODS: This retrospective outcomes analysis comprised 23 eyes (20 patients) having wavefront-guided flap-lift (19 eyes) or photorefractive keratectomy (4 eyes) enhancements after conventional non-wavefront-guided laser in situ keratomileusis (LASIK) for correction of residual myopia with a minimum follow-up of 1 month. Main outcomes measures were changes in lower-order aberrations and higher-order aberrations (HOAs) related to predictability of the refractive outcome. RESULTS: The enhancement procedures reduced HOAs. Because of a hyperopic shift, however, uncorrected visual acuity (UCVA) improved 2 or more Snellen lines in 3 of 9 eyes (33.3%) treated without a surgeon offset compared with 9 of 14 (64.3%) when a surgeon offset was incorporated into the treatment plan. The quantitative amount of preoperative HOAs correlated with the amount of hyperopic shift, particularly strongly for spherical aberration (r(2) = 0.446, P = .0005). The amount of hyperopic shift was related in a linear manner to the amount of HOAs (for spherical aberrations, Y = 1.31X - 0.30, where Y is the postoperative manifest refraction spherical equivalent and X is the wavefront error in microns root mean square). CONCLUSIONS: Wavefront-guided enhancements can reduce levels of HOAs. Although UCVA improved in many patients, some with high levels of preenhancement spherical aberration had worse UCVA. Adjusting the nomogram for the amount of preenhancement HOAs may improve the accuracy of the lower-order correction in wavefront-guided enhancements.     

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.     

Inadvertent stromal dissection during mechanical separation of the corneal epithelium using an epikeratome

Epithelial flap complications occurred in 2 patients during epithelial separation using a Centurion SES epikeratome (Norwood Eye Care) in epi-laser in situ keratomileusis (LASIK). The complications consisted of stromal dissection at the margin of the pupil and an epithelial free cap including the superficial stroma. The epithelial flaps were repositioned without laser ablation. Three months postoperatively, the best corrected visual acuity in both patients was 20/20 and neither complained of visual discomfort. Slitlamp biomicroscopic examination showed that both corneas were completely healed with trace opacity, and topographic examinations revealed that irregularities in the stromal cutting sites were decreased. The patients had successful photorefractive keratectomy after complete healing of the dissected stroma. Stromal dissection during mechanical separation of the epithelium with an epikeratome is a potential complication of the epi-LASIK procedure, but proper management can result in good recovery without severe visual impairment.     

Partial dislocation of laser in situ keratomileusis flap by air bag injury

PURPOSE: A patient developed significant corneal complications from air bag deployment, 17 months after laser in situ keratomileusis (LASIK). METHODS: Case report, slit-lamp microscopy, and review of the medical literature. RESULTS: A 37-year-old woman underwent bilateral LASIK with resultant 20/20 uncorrected visual acuity. Seventeen months later, she sustained facial and ocular injuries from air bag deployment during a motor vehicle accident. Examination revealed bilateral corneal abrasions, partial dislocation of the right corneal LASIK flap, and a hyphema in the right eye. The LASIK flap was realigned, but recovery was complicated by a slowly healing epithelial defect and flap edema. One month following the injury, epithelial ingrowth beneath the LASIK flap was noted. Surgical elevation of the flap and removal of the epithelial ingrowth was performed. Eight months later, epithelial ingrowth was absent and the visual acuity was 20/40. Residual irregular astigmatism necessitated rigid gas permeable contact lens fitting to achieve 20/20 visual acuity. CONCLUSIONS: Air bags may cause significant ocular trauma. The wound healing response of LASIK allows corneal flap separation from its stromal bed for an indeterminate time after surgery. Discussion of the possible risk of corneal trauma as part of informed consent prior to LASIK may be appropriate.