Search

Myopia is a generally benign refractive error with an increasing prevalence worldwide. It can be corrected temporarily with glasses and contact lenses and permanently with laser vision correction. The 2 main procedures currently being performed for myopia correction are photorefractive keratectomy and laser-assisted in situ keratomileusis. Each technique has its advantages, but they appear to yield similar visual outcomes 1 year after surgery. Laser vision correction for myopia was considered a paradigm shift because healthy eyes could now undergo a surgical procedure to permanently and safely correct the error by altering the center of the cornea, which was previously off limits because of the potential for loss of transparency. Customized ablation using wavefront aberrometry and its optimized profiles were created to correct higher-order aberrations and give more vision quality to patients. Topography-guided ablation, initially used for complex retreatments, shows potential to make vision even better than glasses and contact lenses in a recent study on previously untreated eyes. One major concern is to identify corneas that are at risk of developing ectasia after the procedure. Topographic and tomographic screening indices have been implemented clinically, but there is still much to learn about corneal biomechanics. A more recently developed procedure for myopia correction is small-incision lenticule extraction, in which a lenticule is created in the cornea's stroma with a femtosecond laser and extracted through a small corneal incision. Long-term outcomes and new complication risks need to be better understood as this procedure develops.

Purpose: To investigate the association of the percent tissue altered (PTA) with the occurrence of ectasia after LASIK in eyes with suspicious preoperative corneal topography., Methods: This retrospective comparative case-control study compared associations of reported ectasia risk factors in 129 eyes, including 57 eyes with suspicious preoperative Placido-based corneal topography that developed ectasia after LASIK (suspect ectasia group), 32 eyes with suspicious topography that remained stable for at least 3 years after LASIK (suspect control group), and 30 eyes that developed ectasia with bilateral normal topography (normal topography ectasia group). Groups were subdivided based on topographic asymmetry into high- or low-suspect groups. The PTA, preoperative central corneal thickness (CCT), residual stromal bed (RSB), and age (years) were evaluated in univariate and multivariate analyses., Results: Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons (P < .003) except high- and low-suspect ectasia groups (P = .033), and presented the highest discriminative capability of all variables evaluated. Age was only significantly different between the high-suspect ectasia and normal topography ectasia groups, and CCT was not significantly different between any groups. Stepwise logistic regression revealed the PTA as the most significant independent variable (P < .0001), with RSB the next most significant parameter., Conclusions: There remains a significant correlation between PTA values and ectasia risk after LASIK, even in eyes with suspicious corneal topography. Less tissue alteration, or a lower PTA value, was necessary to induce ectasia in eyes with more remarkable signs of topographic abnormality, and PTA provided better discriminative capabilities than RSB for all study populations., (Copyright 2015, SLACK Incorporated.)

Unlabelled: We describe the case of a 50-year-old woman with anterior basement membrane dystrophy and dry eyes who had femtosecond laser in situ keratomileusis (LASIK) with gas-bubble breakthrough during flap creation in both eyes. The gas-bubble breakthrough appeared beneath the applanation interface in advance of the leading laser edge in the right eye and behind the advancing laser edge in the left eye. The surgery was aborted and 5 days later, photorefractive keratectomy with mitomycin-C was performed in the right eye and LASIK in the left eye. When a gas-bubble breakthrough extends in front of the advancing laser edge of the flap, the surgery should be aborted; surface ablation can be performed as a second-stage procedure. However, if the breakthrough occurs behind the advancing laser edge, the flap can be carefully lifted and the LASIK completed., Financial Disclosure: Dr. Krueger is a consultant to Alcon Laboratories, Inc. Dr. Ribeiro has no financial or proprietary interest in any material or method mentioned., (Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare the changes in corneal power (ΔK) induced by myopic ablations estimated by Placido-disk and total corneal power (TCP) ray tracing methods to the refractive change (ΔSE)., Methods: Manifest refraction, simulated keratometry from a Placido-disk based system, and TCP from a dual-Scheimpflug analyzer were obtained from 35 patients (58 eyes) before and 3 months after a myopic ablation. The change in the manifest refraction that occurred after surgery was then vertex distance corrected and compared to the changes observed in corneal power with the various systems analyzed., Results: The Placido-based simulated keratometry overestimated the corneal power after the procedure by 0.50 ± 0.53 diopters (D) when compared to refractive change in the corneal plane induced by the laser surgery (ΔSE-ΔK). The ray tracing method showed the opposite trend, with the TCP simulated keratometry showing an underestimation of the corneal power of -0.25 ± 0.48 D. The Placido system showed a direct correlation between the overestimation of the corneal power and the level of myopia, whereas the ray tracing method showed an underestimation, which was more pronounced in higher levels of myopia., Conclusions: Ray tracing methods underestimate corneal power as opposed to the overestimation in corneal power after refractive surgery, directly related to the level of myopia, observed in Placido-based systems. They have the potential to overcome the errors in calculations based on anterior curvature alone. However, ray tracing methods need to be validated and optimized before it can be used routinely in IOL calculation., (Copyright 2013, SLACK Incorporated.)

Background: To investigate the association between femtosecond laser flap parameters, uncorrected distance visual acuity, and higher-order aberrations (HOA) after customized myopic LASIK., Methods: Retrospective review of the charts of patients who underwent uncomplicated wavefront-guided customized myopic LASIK with flap creation using the femtosecond laser. Patients were stratified by intended flap thickness, and the change in HOA from preoperative to 3 months postoperative was compared. Multivariate linear models were performed to assess the association between calculated flap thickness, intended flap diameter, HOA, and uncorrected visual acuity., Results: One hundred seventy-one eyes of 171 patients were included. There was no statistically significant difference in the induction of HOA between eyes with thin (90 μm) or thick (100 or 110 μm) intended flaps. In a multivariate model, the level of myopic correction was highly associated with the induction of total HOA, coma, and spherical aberration. There was no correlation between calculated flap thickness, uncorrected visual acuity, or HOAs. Intended flap diameter was not associated with coma or spherical aberration, but larger flap diameter was associated with better uncorrected visual acuity., Conclusions: Femtosecond laser flap thickness in the range of 90-110 μm was not associated with uncorrected visual acuity or the induction of HOA after uncomplicated customized myopic LASIK. The level of myopic correction was the largest determinant of the induction of HOA.

Purpose: To analyze the induced corneal higher order aberrations (HOAs) after wavefront-optimized ablation., Methods: Sixty-four myopic eyes that underwent wavefront-optimized myopic LASIK were divided into three groups based on spherical equivalent (SE): low myopia group (23 eyes with SE <-3.00 diopters [D]); moderate myopia group (27 eyes with SE between -3.00 and -6.00 D); and high myopia group (14 eyes with SE >-6.00 D). Total corneal HOA, corneal spherical aberrations, corneal coma through a 6-mm pupil size, and corneal eccentricity were measured with a dual Scheimpflug imaging device preoperatively and 3 months after surgery., Results: An overall increase in total corneal HOA was observed with a mean of 0.18±0.18 μm (P<.01), although this induction was not statistically significant in the low myopic group with a mean of 0.006±0.15 μm (P=.85). Root-mean-square spherical aberration varied the most after myopic ablation, with an overall induction of positive spherical aberration of 0.27±0.25 μm (P<.001)., Conclusions: Although the wavefront-optimized profile was designed to preserve the preoperative HOAs of the total eye, a significant induction of the corneal HOAs after myopic treatment was observed. The magnitude of the induced corneal HOA was related to the amount of intended correction. Corneal wavefront profiles do not reflect the visual performance; however, they provide relevant information, which may help in optimizing new laser treatment algorithms., (Copyright 2013, SLACK Incorporated.)

Purpose: To report the visual outcomes and change in spherical aberration in the first cohort of eyes treated at the Cole Eye Institute using the FS200 laser (Alcon Laboratories Inc)., Methods: A chart review was performed on 100 eyes targeted for emmetropia with wavefront-optimized femto-LASIK using the WaveLight Allegretto Wave Eye-Q (Alcon Laboratories Inc) and FS200 lasers. Patients were subdivided into low (< -3.00 D, n = 23), moderate (-3.00 to -6.00 D, n = 45), and high myopia (> -6.00 D, n = 2). Pre- and 3- to 9-month postoperative wavefront aberrometry and uncorrected distance visual acuity (UDVA) were compared., Results: An increase was found in spherical aberration of 0.03 +/- 0.02 microm (P = .14) for low myopia, but decreases were found of 0.01 +/- 0.01 microm (P = .45) for moderate myopia and 0.02 +/- 0.04 microm (P = .48) for high myopia. An increase in coma was noted of 0.02 +/- 0.02 microm (P = .37), 0.04 +/- 0.02 microm (P = .02), and 0.11 +/- 0.04 microm (P = .01) for low, moderate, and high myopes, respectively. An increase was found in total higher order aberrations of 0.05 +/- 0.04 microm (P = .17), 0.04 +/- 0.01 microm (P = .01), and 0.11-0.03 microm (P = .01) for low, moderate, and high myopes, respectively. Uncorrected distance visual acuity of 20/15 and 20/20 was achieved in 70% and 91% of low myopes, 58% and 93% of moderate myopes, and 34% and 78% of high myopes, respectively., Conclusions: Wavefront-optimized femto-LASIK with the WaveLight Allegretto Wave Eye-Q and FS200 lasers achieved excellent postoperative UDVA outcomes, with no significant induction of spherical aberration at all refractive errors.

Purpose: To evaluate the posterior corneal surface response at a very early stage after myopic laser in situ keratomileusis (LASIK) with different ablation depths., Setting: Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA., Design: Cohort study., Methods: Healthy myopic eyes were divided based on the achieved ablation depth as follows: Group 1, more than 100 μm; Group 2, between 50 μm and 99 μm; Group 3, less than 50 μm. Posterior eccentricity and central (0.0 to 4.0 mm), paracentral (4.0 to 7.0 mm), and peripheral (7.0 to 10.0 mm) posterior corneal curvatures were measured with the Galilei system preoperatively and postoperatively after 1 day, 1 week, and 1 and 3 months., Results: Eighty eyes were evaluated. Posterior surface steepening and a shift toward prolateness occurred in all groups, with a peak within the first week before returning toward the original level after 1 month. The maximum change in the central posterior cornea occurred after 1 day in Group 1 and reached -0.106 diopter (D). This change was statistically significant (P=.03) and statistically greater than the change in Group 2 (mean -0.042 D; P = 0.02) and Group 3 (mean -0.026 D; P<.01). This change was not significant after 3 months (P = .5)., Conclusions: Posterior steepening and a shift toward prolateness of the posterior surface were observed very early after myopic LASIK, with a tendency to return toward the preoperative level between 1 month and 3 months. The degree of change was related to the amount of anterior tissue severed., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To provide an overview of the clinical results of different ablation profiles based on wavefront technology and discuss their characteristics and limitations., Methods: Literature review of studies reporting results of ablation profiles based on wavefront technology in virgin healthy eyes., Results: Over the past 10 years, a large number of studies comparing different treatment algorithms and newer excimer laser platforms have been published. Thirty-six clinical studies including 3637 eyes analyzing the clinical results obtained after wavefront-guided, wavefront-optimized, and Q-factor profiles have been reviewed. Although wavefront-driven profiles allowed reduction of the amount of induced optical aberrations with conventional ablations, thereby improving the quality of vision, it appears that no algorithm of treatment or excimer laser platform has demonstrated a clear superiority over another. Wound healing and unexpected biomechanical response to surgery affect the accuracy of customized treatments and produce variable results. In addition, it is difficult to rigorously analyze and compare findings among different studies because of the diverse variety in which the data are reported., Conclusions: Despite several technological improvements over the years, wavefront ablation profiles have not consistently demonstrated superiority in terms of visual acuity and lower order aberrations compared to the standard procedure, although the induction of higher order aberrations has been reduced. The concept of an individualized eye model has emerged recently, based on the optical ray tracing algorithm, and could theoretically provide a higher level of customization, thus fulfilling the promise of "super vision.", (Copyright 2012, SLACK Incorporated.)

Purpose: To describe the outcomes of the first 285 eyes receiving LASIK or photorefractive keratectomy (PRK) using an optimized ablation profile at a refractive surgery practice experienced with customized ablation., Methods: A retrospective chart review was performed on all patients who underwent refractive treatments using the ALLEGRETTO WAVE Eye-Q platform (Alcon Laboratories Inc) between September 2008 and July 2009. Patients were divided into LASIK and PRK treatments, then further subdivided based on pre- and targeted postoperative refraction. Pre- and postoperative measures of uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest refraction, keratometry, and wavefront values were taken and compared, and the average changes in keratometry and higher order aberrations were calculated., Results: At 3 months postoperative, 92% of myopes and 63% of hyperopes undergoing LASIK with a target of emmetropia achieved UDVA of 20/20. Of PRK eyes targeted for emmetropia, 80% of myopic eyes achieved UDVA of 20/20 (the hyperopic subgroup was too small to analyze). In both LASIK and PRK subgroups, total wavefront aberrations decreased, as did some higher order aberrations., Conclusions: This group of patients, who all achieved excellent postoperative UDVA, represents our initial surgical experience with the ALLEGRETTO WAVE, using only a standard (global surgeon) nomogram. These results may serve as an estimate of what a practice could expect in terms of initial outcomes with this system., (Copyright 2010, SLACK Incorporated.)

Purpose: To evaluate the risk factors for interface haze formation after thin-flap femtosecond laser--laser in situ keratomileusis (LASIK)., Design: Prospective case series., Methods: One hundred and ninety-nine consecutive eyes that underwent femtosecond laser LASIK with a LADAR 4000 excimer laser (Alcon Laboratories, Fort Worth, Texas, USA), were analyzed from January 1 to April 30, 2008. Treated eyes were divided into 2 groups according to desired flap thickness: 90 microm (106 eyes), and 100 to 110 microm (93 eyes). Cycloplegic refraction, spherical equivalent (SE), uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), depth of ablation, central corneal thickness, flap thickness (optical coherence tomography), Scheimpflug images (Pentacam; Oculus Inc, Lynnwood, Washington, USA), and light scattering were assessed in all eyes that developed haze postoperatively., Results: Haze was observed in 32 eyes treated for moderate to high myopia (SE -6.23 +/- 1.67 diopters and depth of ablation 94.6 +/- 22.9 microm) at 3 months postoperatively. Ultra-thin IntraLASIK flaps (

Purpose: To report the incidence of and factors associated with rainbow glare after laser in situ keratomileusis (LASIK) flap creation with a 60 kHz femtosecond laser., Setting: Department of Refractive Surgery, Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA., Methods: Consecutive patients having LASIK by the same surgeon were questioned during postoperative examinations or by telephone about postoperative rainbow glare (radiating colors around a white light at night). Femtosecond laser (IntraLase) settings included pulse frequency 60 kHz, flap thickness 90 to 110 mum, and spot/line separation 8 mum. Raster energy was 0.8 microJ (75% of eyes) and 1.0 to 1.1 microJ (25%). Excimer laser ablation was performed with the LADAR 4000 or 6000 platform using custom or conventional treatments., Results: Of 260 consecutive patients, 256 (98.5%) were successfully contacted. Fifteen patients (28 eyes) reported postoperative rainbow glare (5.8%), described as 4 to 12 bands of color around a white light, with 6 bands most common. The symptom did not correlate with refractive error, age, or sex but was more frequent at 1.0 microJ or 1.1 microJ raster energy (11.6%) than at 0.8 microJ (4.1%). The incidence followed a bimodal distribution, with the first grouping due to inadequate alignment and higher energy just after laser installation and the second just before a later maintenance service call., Conclusion: Rainbow glare is a mild optical side effect of femtosecond LASIK. In this study, higher raster energy levels and length of time between service calls were associated with the occurrence of rainbow glare.

Purpose: To describe a series of myopic patients in whom a LASIK flap was created with the IntraLase femtosecond laser. The LADARVision (Alcon Laboratories Inc) tracking system failed and resulted in postponement of surgery., Methods: Five myopic Asian patients with darkly pigmented irides underwent bilateral superior hinge flap creation with three different femtosecond laser (IntraLase Corp) pulse frequencies: 15, 30, and 60 kHz. Mean patient age, preoperative best spectacle-corrected visual acuity (BSCVA), and spherical equivalent refraction were 33 years, 20/20, and -6.25 diopters (D), respectively. Despite uncomplicated flap-lift and adequate pharmacologic dilated pupil diameter >7 mm, difficulty was experienced with LADARVision eye tracking in 9 of 10 eyes. Intraoperative manipulations (fluid application, levitation of the laser bed, and tracking through a repositioned flap) were attempted to facilitate eye tracking at the time of femtosecond laser flap creation, but without success., Results: The flap was repositioned, and patients were asked to return 1 to 5 days later, at which time the flap was relifted, eye tracking was successfully achieved, and the surgery was completed. Mean postoperative uncorrected visual acuity was 20/18 and no eyes lost any lines of BSCVA at 1 year., Conclusions: Irregularities of the IntraLASIK stromal bed surface induce forward light scatter, and dark ocular pigmentation further reduces retinal reflectance, leading to tracking failure with the Alcon LADARVision platform. Delaying the surgery by 1 to 5 days may aid in reducing the light scatter, so that eye tracking can be achieved.

Purpose: To report a new optical side effect associated with the IntraLASIK procedure., Design: Retrospective chart review and questionnaire of all patients treated with IntraLASIK from June 2004 to August 2005., Participants: A cohort of 585 eyes (312 patients) was divided sequentially into those treated with the older-model IntraLase laser (group 1: 399 eyes of 215 patients) and those treated with the newer model (group 2: 186 eyes of 97 patients)., Methods: Preoperative and postoperative refraction, visual acuity, pupillometry, pachymetry, intraocular pressure, mean topographic power and cylinder, wavefront aberrations, and answers to a questionnaire of symptoms were recorded. The precise spatial extent of the rainbow spectrum was drawn by select patients for calculation of the diffractive grating size responsible for the light scatter. A glass slide was also irradiated and photographed using the older model to simulate the rainbow spectrum., Main Outcome Measures: The symptom of rainbow glare was correlated with preoperative and postoperative factors and time between the most recent service call and surgery., Results: In group 1, 90.2% of patients were successfully contacted, and 37 (69 eyes) reported symptoms of rainbow glare around lights, for an incidence of 19.07%. In group 2, 88.6% of patients were contacted, and 2 (4 eyes) reported similar symptoms, for an incidence of 2.32%. The odds ratio (OR) between the 2 groups is 9.4 (P<0.001). For every 10-mum increase in ablation depth, the OR is 1.2 (P = 0.038), and for every 30 days from the last service call, it is 1.5 (P = 0.007). The spatial extent of the color pattern was used to calculate the spacing array at approximately 9 mum, corresponding to the laser spot and line separation., Conclusions: Light scattering from the back surface of the IntraLASIK flap creates a spectral pattern whose visual impact is clinically inconsequential in the majority of patients. The spectral pattern and visual angle correspond to a grating size that matches the raster spot separation of IntraLase pulsing. Eyes treated with newer focusing optics of higher numerical aperture reduced the rainbow symptom. Variance in optical quality and numerical aperture can impact the spot size and uniformity of IntraLase flap creation.

Purpose: To evaluate the clinical outcomes of custom topographic neutralizing technique in treating highly aberrated eyes using the WaveLight ALLEGRETTO WAVE Excimer Laser., Methods: A retrospective consecutive case series of 67 eyes with decentered ablations and 48 eyes with symptomatic small optical zones after previous LASIK underwent topography-guided retreatment with the ALLEGRETTO WAVE. Sixteen keratoconus eyes underwent topographic neutralizing technique photorefractive keratectomy (PRK). The study assessed preoperative and 6-month and 1-year postoperative results regarding best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), topography, and predictability., Results: Sixty-seven eyes with previously decentered optical zones had an improvement of centration from 0.92 mm preoperatively to 0.30 mm postoperatively relative to pupil center (P<.01). Twenty-nine percent of these eyes gained 1 or more lines of BSCVA, whereas 71% had no change in BSCVA. Forty-eight eyes with previously small optical zones had an increase of the central monodioptric optical zone from 3.9 mm to 5.6 mm (P<.01). Nineteen percent of eyes had an improvement of at least 1 line, whereas 75% had no change in BSCVA and 6% lost 1 line. Sixteen keratoconus eyes had custom topographic neutralizing technique PRK as an alternative to penetrating keratoplasty. All eyes had improvement of astigmatism up to 5.00 diopters (D), with a mean change of 1.68+/-1.62 D. Best spectacle-corrected visual acuity was unchanged in 8 (50%) eyes, with 4 (25%) eyes gaining 1 line, 2 (12%) eyes gaining 2 lines, and 2 (12%) eyes losing 1 line of BSCVA at 6 months., Conclusions: Management of some highly aberrated eyes is now possible with topography-guided ablation using the WaveLight ALLEGRETTO platform and custom topographic neutralizing technique. Safety was acceptable for small optical zone and decentered ablation retreatments. The topography-guided ablation could be an alternative treatment for keratoconus patients if keratoplasty is otherwise indicated. The algorithms for custom topographic neutralizing technique need further refinement.

Purpose: To illustrate the challenges associated with a misaligned free flap (cap) and to report the outcome of applying wavefront-guided customized photorefractive keratectomy (PRK) followed by conventional PRK ablation to correct residual refractive error and aberrations after LASIK free cap complications., Methods: The clinical course and surgical interventions of two patients with free cap complications from LASIK surgery were reviewed. The first patient underwent a total of six interventions after the initial LASIK procedure, and the second patient underwent a total of five interventions. Interventions included cap lift, cap rotation, custom PRK, and conventional PRK enhancement with prophylactic topical mitomycin C (MMC)., Results: Customized PRK treatment and subsequent enhancements with prophylactic topical MMC led to the recovery of best spectacle-corrected visual acuity (BSCVA), neutralization of higher and lower order aberrations, and astigmatic neutrality. Symptoms related to higher order aberrations resolved in both patients., Conclusions: Wavefront-guided custom PRK for higher order aberrations followed by conventional PRK enhancement for residual lower order aberrations, both with topical MMC application, represents an efficacious strategy for treating patients with loss of BSCVA and visual symptoms due to LASIK free cap complications.

Purpose: To retrospectively compare the safety and efficacy of lower dose mitomycin C (MMC) (0.002%) to that of the standard dose (0.02%) in eyes treated with photorefractive keratectomy (PRK) for myopia., Methods: The clinical efficacy of 95 eyes receiving myopic PRK with a standard concentration of MMC (0.02%) is sequentially compared to 126 eyes receiving low dose MMC (0.002%). The topical exposure times for MMC varied between 30 seconds and 2 minutes in both groups, and direct contralateral eye comparison of these two exposure times was analyzed in a prospective subset of 39 patients from among the low dose group. Patients were examined preoperatively and postoperatively at 1, 3, 6-9, and 9-12 months. Haze, visual acuity, and efficacy ratio outcomes were analyzed., Results: The preoperative findings were overall statistically similar, except for higher spherical equivalent refractive error (P = .007) and best spectacle-corrected visual acuity (P = .007) in the standard MMC group. Postoperatively, haze levels ranged from 0 to 4+. With multivariable analysis, significantly less haze was noted among the standard dose MMC eyes for high myopia and higher ablation depth at all postoperative time points. In contrast, the haze levels were statistically similar for moderate myopia and lower ablation depths at the latter postoperative time points. The subset of contralateral eyes randomly receiving low dose MMC (0.002%) at either 30 seconds or 2 minutes exposure showed no significant difference in haze between these exposure times., Conclusions: The standard concentration of topical MMC (0.02%) is more effective than low dose MMC (0.002%) in preventing postoperative haze following surface ablation for myopia > or = -6.00 D and deeper ablation depth > or = 75 microm. However, for moderate myopia and shallow depth, low dosing appears to be equally effective. The duration of MMC exposure appears to be less important than its concentration.