Long-Term Outcomes of Refractive Surgery Performed During the Military.

INTRODUCTION: To evaluate the long-term refractive results of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) performed by the military in a veteran population. MATERIALS AND METHODS: Three Department of Veterans Affairs (VA) hospital sites (Puget Sound, Buffalo, and Washington D.C.) obtained IRB approval for this multi-center study. Comprehensive ophthalmologic assessment including refraction and keratometry were obtained at the time of the long-term VA examination and compared to the patients' postoperative military records. RESULTS: Eighty patients (160 eyes) enrolled in this study. At the time of treatment, patients were 21-52 years of age. Long-term post-operative data was available from 4 to 17 years post-operatively. Fifteen percent of the treatment types were LASIK and 85% PRK. At the time of their military post-operative exam (range 3-14 months, mean 4 months), 82% of patients had uncorrected visual acuity (UCVA) of 20/20 or better, and their average manifest refraction was -0.08 D (SD ± 0.48 D). At the time of the long-term ophthalmological exam at the VA medical centers (range 4-11 years, mean of 8.2 years), 49% of patients had an UCVA of 20/20 or better and an average manifest refraction was -0.64 D (SD ± 0.69 D). CONCLUSION: This is the first long-term study evaluating refractive surgery outcomes up to 17 years in a military population. Our study demonstrates safety after refractive surgery in the military with less than 0.1D increase in myopia per year and strong keratometric stability. Other changes in the eye may be the likely cause for this observed mild refractive shift.

Avoidance of serious medical errors in refractive surgery using a custom preoperative checklist.

PURPOSE: To implement and measure the effect of a surgical safety checklist on the prevention of serious medical errors (never-events). SETTING: Boston Eye Group, Boston, Massachusetts, USA. DESIGN: Retrospective cohort study. METHODS: A safety checklist incorporating 28 sources of error was designed and implemented in December 2011 at the Boston Eye Group's refractive surgical center. Consecutive patients who had primary or enhancement laser vision correction (LVC) between July 2009 and February 2014 were included in this study. Before that date, a general checklist fashioned around the World Health Organization time-out procedure was used. The latter subjects were recruited as controls. The perioperative characteristics of both groups were retrospectively compared. RESULTS: The study comprised 2951 consecutive patients who had primary or enhancement LVC between July 2009 and February 2014; of these, 1417 patients (2744 eyes) had LVC after the implementation of a presurgical safety checklist. The general checklist fashioned around the World Health Organization time-out procedure was used for 1534 patients (2969 eyes). Both groups were comparable in patient age. The most common surgical procedures were laser in situ keratomileusis (78%) and laser-assisted subepithelial keratectomy with mitomycin-C (16%). Although there were 2 (0.07%) serious errors in the prechecklist cohort, none occurred following implementation of the safety checklist protocol (P = .23). The medical errors involved wrong refractive aim in 1 patient and wrong person-wrong procedure-wrong aim in another. CONCLUSIONS: Multiple potential sources of error exist in refractive surgery. The broad-scale implementation of a detailed presurgical safety checklist was helpful in minimizing and preventing serious errors (never-events) during LVC. FINANCIAL DISCLOSURE: Drs. Shapiro and Urman are members of the Institute for Safety in Office-Based Surgery, a nonprofit organization whose aims are to implement safety checklists for office-based surgery. No author has a financial or proprietary interest in any material or method mentioned.

[Topographically-guided photorefractive keratectomy for the management of secondary hyperopia following radial keratectomy]. / Ceratectomia fotorrefrativa baseada em topografia para correção da hipermetropia secundária à ceratotomia radial.

PURPOSE: To describe a topographically guided photorefractive keratectomy technique for the management of secondary hyperopia following radial keratectomy. METHODS: A retrospective study was carried out in patients where a topographically guided photorefractive keratectomy technique was performed for the management of secondary hyperopia following radial keratectomy. The patients had preoperatively at least 3 diopters of hyperopia. The minimum follow-up was 3 months. RESULTS: Twenty-four eyes of 21 patients were evaluated. The mean age was 45.54+/-6.03 years (range 36 to 55 years). The average follow-up was 7.71+/-4.6 months (range 3 to 17 months). Preoperatively the average spherical equivalent was +3.92+/-1.57 (range +1.25 D to +7.75 D), and postoperatively it was -0.29+/-1.43 (range -3.75 D to +2.50 D) (p<0.01). Visual acuity of 20/25 or better was achieved in 45.83% of the eyes, 20/40 or better in 83.33% and 20/60 or better in 100%. All patients were satisfied with the results and stated subjective improvement in visual quality. CONCLUSION: Considering that it is a retreatment procedure performed in unstable and irregular corneas with high degrees of hyperopia, topographically guided photorefractive keratectomy showed good results and was safe and effective for the management of secondary hyperopia following radial keratectomy.

Ceratectomia fotorrefrativa baseada em topografia para correção da hipermetropia secundária à ceratotomia radial / Topographically-guided photorefractive keratectomy for the management of secondary hyperopia following radial keratectomy

OBJETIVO: Descrever nova técnica de ceratectomia fotorrefrativa baseada em topografia para correção da hipermetropia secundária à ceratotomia radial. MÉTODOS: Estudo retrospectivo realizado em pacientes submetidos a ceratectomia fotorrefrativa baseada em topografia para a correção da hipermetropia secundária à ceratotomia radial. Os pacientes apresentavam, no mínimo, 3 dioptrias de hipermetropia no pré-operatório, e apresentavam acompanhamento mínimo de 3 meses. RESULTADOS: Neste estudo foram avaliados 24 olhos de 21 pacientes com idade entre 36 e 55 anos (média de 45,54 ± 6,03 anos). O período médio de acompanhamento foi de 7,71 ± 4,6 meses (variando de 3 a 17 meses). A média do EE no pré-operatório foi de +3.92 ± 1.57, com variação de +1,25 D a +7,75 D e após a ablação, a média foi -0,29 ± 1,43 variando de 3,75 D a +2,50 D (p<0,01). Acuidade visual de 20/25 ou melhor foi encontrada em 45,83 por cento dos olhos analisados, 83,33 por cento apresentaram visão de 20/40 ou melhor e 100 por cento dos olhos com 20/60 ou melhor. Todos os pacientes ficaram satisfeitos com o resultado cirúrgico e referiram melhora subjetiva da qualidade visual. CONCLUSÃO: Ao se avaliar os resultados aqui apresentados, consideramos a ceratectomia fotorrefrativa baseada em topografia mais uma opção para a correção da hipermetropia secundária à ceratotomia radial. Como é um procedimento de retratamento realizado em olhos com córneas muito instáveis e irregulares e com alto grau de hipermetropia, pode-se considerar bons os resultados e que a técnica é segura e eficaz.

PURPOSE: To describe a topographically guided photorefractive keratectomy technique for the management of secon dary hyperopia following radial keratectomy. METHODS: A retrospective study was carried out in patients where a topographically guided photorefractive keratectomy technique was performed for the management of secondary hyperopia following radial keratectomy. The patients had preoperatively at least 3 diopters of hyperopia. The minimum follow-up was 3 months. RESULTS: Twenty-four eyes of 21 patients were evaluated. The mean age was 45.54 ± 6.03 years (range 36 to 55 years). The average follow-up was 7.71 ± 4.6 months (range 3 to 17 months). Preoperatively the average spherical equivalent was +3.92 ± 1.57 (range +1.25 D to +7.75 D), and postoperatively it was -0.29 ± 1.43 (range -3.75 D to +2.50 D) (p<0.01). Visual acuity of 20/25 or better was achieved in 45.83 percent of the eyes, 20/40 or better in 83.33 percent and 20/60 or better in 100 percent. All patients were satisfied with the results and stated subjective improvement in visual quality. CONCLUSION: Considering that it is a retreatment procedure performed in unstable and irregular corneas with high degrees of hyperopia, topographically guided photorefractive keratectomy showed good results and was safe and effective for the management of secondary hyperopia following radial keratectomy.

Shack-Hartmann-Based wavefront analyzer for calibrating excimer lasers.

PURPOSE: Currently, refractive surgical excimer laser systems are calibrated by ablating plastic lenses, which are measured by lensometer and analyzed by a technician. The accuracy of this method is approximately 0.25 diopters (D) in sphere and cylinder power. Theoretically, objective calibration using wavefront technology would be significantly more accurate, thereby improving surgical outcomes. This study describes a Shack-Hartmann-based instrument, which has been developed to measure ablated plastic lenses for calibration and quality control of the excimer laser. METHODS: A calibration instrument comprising an LED source at 640 nm, a lenslet array, beam-guiding optics, and a CCD camera was designed to perform full wavefront analysis. The measurement plane is conjugate to the lenslet array plane, and the diameter of the pupil is 5 mm. Accuracy was determined by measuring a set of well-calibrated spherical and cylindrical glass lenses. Plastic lenses were ablated, and high-precision measurements were performed by surface profile scanner. RESULTS: In the power range of -6.00 to +4.00 D, repeatability exceeded 0.01 D, accuracy of measurement exceeded 0.04 D, and 10 for the axis of cylinder lenses. The measurement of excimer-ablated plastic lenses agreed with high-precision surface profile scanner measurements within 0.10 D, and repeatability exceeded 0.01 D. CONCLUSIONS: Wavefront technology-based, high-precision measurement of calibration lenses can more accurately set the energy of the excimer laser, which enhances the accuracy of refractive laser correction. In automating calibration, the new instrument removes operator subjectivity and decreases the time needed for calibration.

Evidence for superior efficacy and safety of LASIK over photorefractive keratectomy for correction of myopia.

PURPOSE: To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia. DESIGN: Meta-analysis/systematic review. PARTICIPANTS: Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database. METHODS: A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken. MAIN OUTCOME MEASURES: Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20). RESULTS: Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001). CONCLUSIONS: LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.

[ISO 9001-2000 certification for refractive laser treatment]. / Certification ISO 9001-2000 des traitements réfractifs par laser cornéen.

PURPOSE: To obtain ISO 9001-2000 certification for laser corneal refractive treatment, never before sought in Europe. MATERIAL AND METHODS: The consulting firm Veritas led the certification process with the clinic's staff manager. This ISO norm is dedicated to the implementation of a quality management system. We assessed and optimized all necessary resources, evaluating customer satisfaction using patient and referring-physician surveys. We started quality rounds including surgeons, nurses, and technicians. Based on this preparation, we redefined and explained all processes including staff responsibilities and necessary resources in the quality manual. The procedure lasted 14 months with substantial involvement on the part of the management. RESULTS: Unconditional ISO 9001-2000 certification was granted by the independent audit firm, BVQI, in december 2003 for refractive laser treatment. CONCLUSION: The 2000 version of the new ISO 9001-2000 seeks to meet the demand for improving health care delivery in this field, most particularly by establishing a clear procedural orientation. Such certification enhances team work, stabilizes methodologies, and reinforces cohesion and self-audit. Patients notice that the center follows a consistent quality policy and are assured that the clinic respects rules and regulations. Certification is an advantageous alternative when accreditation cannot be considered. Our article discusses the steps taken in upper management, quality management, procedural guidance, as well as customer and staff counselling. It also discusses the project's cost/benefit ratio for the organization.

Smoothness of ablation on polymethylmethacrylate plates with four scanning excimer lasers.

PURPOSE: To perform a quantitative evaluation of smoothness of ablation on polymethylmethacrylate (PMMA) using four scanning excimer lasers available commercially for photorefractive surgery. METHODS: Ablations were done on PMMA plates with dimensions 100 x 50 x 1 mm. Four scanning excimer lasers were used, two with flying spot technology (Zeiss-Meditec MEL-70, and a Russian-made unit, Microscan) and two Nidek models with scanning slit delivery systems and an expanding iris diaphragm (EC-5000 and EC-5000 CX). Forty PMMA plates were ablated with standard -3.00-D settings using an ablation zone of 6 mm; each laser ablated 10 plates. Measurements were made in the center of each plate with the Zygo microscope, based on the principle of white light interferometry. Smoothness of ablation was characterized by three surface parameters (RMS, Ra, PV). RMS was considered the most significant parameter. RESULTS: The smoothest surface was obtained in samples produced by Zeiss-Meditec MEL-70 unit (RMS=112 +/- 23 nm), followed by the Nidek EC-5000 CX (RMS=153 +/- 12 nm), and the Microscan (RMS=181 +/- 11 nm). The smoothness of ablation produced by the Nidek EC-5000 unit (RMS=329 +/- 39 nm) was significantly less than the other three lasers (P<.01). CONCLUSIONS: Scanning excimer lasers based on flying spot technology--Zeiss-Meditec MEL-70 and Microscan, as well as the Nidek EC-5000 CX with FlexScan--created smoother ablations on PMMA plates compared to the older Nidek EC-5000 unit.

Update on laser subepithelial keratectomy (LASEK).

PURPOSE OF REVIEW: This study reviews current concepts in laser subepithelial keratectomy (LASEK), variations in LASEK techniques, the role of pharmacology in LASEK, and optimizing outcomes in LASEK. RECENT FINDINGS: Recent studies continue to support the use of LASEK over that of LASIK in the correction of refractive error. In addition, the advent of pharmacological/biologic intervention, improved algorithms, and wavefront technology have expanded the armamentarium available to ophthalmologists in the maximization of LASEK outcomes. SUMMARY: LASEK offers an excellent profile in terms of both final outcome (uncorrected visual acuity) and safety (best corrected visual acuity). Untoward effects of LASEK are readily prevented/treated with a variety of agents. Postoperative pain can be ameliorated using topical and oral analgesia. Infection can be most effectively addressed with the fourth generation of fluoroquinolones. Haze may be treated or prevented using numerous remedies namely autologous serum, steroids, ascorbic acid, mitomycin-c, and NSAIDS. Wavefront combined with LASEK rather than with LASIK may offer the best refractive outcome.

Comparative study of ablation profiles of six different excimer lasers.

PURPOSE: To compare the morphological features of photorefractive ablations produced by six different excimer lasers. METHODS: A spherocylindrical photoablation (-2.00 -2.00 x 90 degrees; 6-mm optical zone) was performed on regular fluence plates with six excimer lasers: Bausch & Lomb Technolas 217C, Schwind Esiris, Kera Technology Isobeam D200, Ladarvision 4000, Zeiss Meditec MEL 70 G-Scan, and Visx Star S3. Morphometric analysis of the fluence plates provided superficial measurements of the ablated areas. RESULTS: Two areas were identified visually: a central area with a complete ablation of the metallic surface layer and a surrounding area with a partial ablation. The dimensions of the ablated areas were highly variable in the lasers tested. The major differences appeared in the total ablated area (ranging from 38.55 mm2 [Schwind] to 81.94 mm2 [Bausch & Lomb] and in the peripheral to total area ratio (ranging from 36.95% [Schwind] to 59.51% [Ladarvision]). CONCLUSION: Large differences appeared in the superficial dimensions and contours of the ablations produced by different excimer lasers for the treatment tested in this study. It remains unknown how these different ablation patterns induce the same optical correction, but we assume that the depth of the ablation compensates for the differences in the surface extension of the ablated areas.

Confocal microscopy evaluation of stromal ablation depth after myopic laser in situ keratomileusis and photorefractive keratectomy.

PURPOSE: To compare the measured ablation depth after myopic laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) with the predicted ablation depth. SETTING: Mayo Clinic, Rochester, Minnesota, USA. METHODS: Twenty-five eyes of 15 patients had PRK and 25 eyes of 15 patients had LASIK to correct refractive errors between -1.50 diopters (D) and -11.00 D. The corneas were examined by in vivo confocal microscopy before and 1 month after both procedures. Thickness measurements were obtained from digital-image analysis of confocal scans. The measured ablation depth, an estimate of the actual photoablation depth, was obtained as the surgically induced stromal thinning between the preoperative and the 1-month post-PRK or post-LASIK central stromal thickness. The predicted ablation depth was recorded from the laser's software program. RESULTS: In LASIK, the measured ablation depth (81 microm +/- 34 [SD]) was 25% greater than the predicted ablation depth (65 +/- 13 microm, P =.007) and the difference between the measured and predicted ablation depths was positively associated with the mean ablation depth (r = 0.81, P<.001). In PRK, there was no difference between the measured ablation depth (48 +/- 19 microm) and the predicted ablation depth (47 +/- 18 microm, P =.84). CONCLUSION: Significantly more tissue than predicted was removed by LASIK than by PRK excimer photoablation with the laser system used in this study.

A new index to measure the accuracy of refractive operations.

PURPOSE: To create a new index to help evaluate the accuracy of the outcome of refractive surgery. METHODS: By combining information given by the cross-cylinder form of surgically induced refractive change (SIRC) and basic methods of vector analysis, we constructed a new index which serves as a tool to evaluate postoperatively the changes achieved by refractive surgery. This new index gives easily understandable numerical values and takes into account changes in both spherical refraction and astigmatism. We demonstrated the use of this index in two study populations consisting of 20 consecutive eyes operated on using two different lasers, Meditec MEL60 and MEL70, respectively. RESULTS: Although postoperative uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were better in the MEL70 group, the difference of photoefractive keratectomy (PRK) for combined astigmatism and myopia was not statistically significant. Comparison of the changes in refraction achieved by the two lasers indicated that the MEL60 was more accurate; this was also seen when comparing the total index of error between the two groups. CONCLUSIONS: We suggest the use of this total index of error (TIE) in clinical praxis because it provides an easy and accurate method of evaluating the accuracy of refractive operations. These inaccuracies might otherwise go unnoticed if the basic values only (e.g. UCVA, BCVA and haze) were used in postoperative evaluation.

Visual and symptomatic outcome of excimer phototherapeutic keratectomy (PTK) for corneal dystrophies.

PURPOSE: To determine the visual results and outcome of excimer laser phototherapeutic keratectomy (PTK) for corneal dystrophies. METHODS: Twenty-nine eyes of 19 patients who underwent excimer PTK for recurrent erosions and reduced vision due to corneal dystrophies, between February 1996 and July 1999, were reviewed. Data regarding the preoperative and postoperative best-corrected visual acuity (BCVA), change in spherical equivalent (SE), depth of excimer laser ablation, symptomatic relief, and incidence of recurrence were analysed by a retrospective chart review. RESULSTS: The range of follow-up was 12-48 months. Twenty-seven out of 29 eyes (93%) maintained or improved BCVA. All patients (17/17) were free of symptoms of recurrent erosions although two eyes needed repeat treatment to achieve this. In those eyes undergoing PTK for reduced vision, there was a trend towards a hyperopic shift postoperatively but this was not statistically significant. Five eyes showed recurrence of the dystrophy (Reis-Bücklers (one eye), Lattice (two eyes), and Granular (two eyes)) that required repeat treatment. Two of these eyes required a single repeat PTK procedure, and three eyes underwent three repeat treatments. There were no major complications during the follow-up period. CONCLUSIONS: Excimer PTK is a safe and effective procedure for relieving symptoms of recurrent erosions and improving visual acuity in patients with corneal dystrophies. Optimal visual results are achieved when treating more anterior disease. Multiple treatments are possible without significant detrimental effects for those patients with recurrence of their dystrophy.

Photorefractive keratectomy.

In this chapter, we have reviewed important aspects of PRK. A thorough understanding of the preoperative assessments, techniques, and postoperative management is essential to achieve satisfactory visual outcomes. Laser safety checks are mandatory. A well-functioning excimer laser with good optics is required. The surgeon must avoid any decentration or global tilt. All aspects of the technique must be performed with attention to detail. The postoperative management requires frequent follow-up visits and psychological reinforcement of a healing process that is not instantaneous. PRK is a procedure in evolution. Although the results today are impressive, the complications in the future will continue to decrease with changes in lasers, techniques, and pharmacological management.

Surgical outcomes of photorefractive keratectomy and laser in situ keratomileusis by inexperienced surgeons.

PURPOSE: To investigate the results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) procedures performed by novice ophthalmologists and compare the results with those of experienced refractive surgeons. SETTING: Doheny Eye Institute, University of Southern California, Los Angeles, and Department of Ophthalmology, University of California, Irvine, California, USA. METHODS: In this retrospective case series, data were examined from the first PRK procedures by 33 consecutive ophthalmologists and the first LASIK procedures by 19 consecutive ophthalmologists. Preoperative and postoperative uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), as well as intraoperative and early postoperative complications, were recorded. RESULTS: In the PRK group, 33.3% of eyes achieved a UCVA of 20/20 and 87.8%, 20/40 or better; 54.5% were within +/-0.5 diopter (D) of emmetropia and 87.8%, within +/-1.0 D. Two eyes with a preoperative spherical equivalent of greater than -11.0 D lost 2 lines of BSCVA. If eyes with low myopia (