All-in-One Femtosecond Laser Refractive Surgery

Bamba S., Rocha K.M., Ramos-Esteban J.C., Krueger R.R.

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.Department of Refractive Surgery, Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA.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.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.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.

Ruiz L.A., Cepeda L.M., Fuentes V.C.

To introduce a new, minimally invasive intrastromal correction for presbyopia (INTRACOR procedure) using the TECHNOLAS femtosecond laser system (Technolas Perfect Vision GmbH).The INTRACOR procedure was performed in 83 eyes of 45 patients aged 44 to 67 years. Follow-up was 6 to 12 months. Data recorded included age; pre- and postoperative refraction; uncorrected distance (UDVA), intermediate, and near visual acuity (UNVA); corrected distance visual acuity (CDVA); distance corrected near visual acuity; corneal hysteresis (CH), corneal resistance factor (CRF), and asphericity; pachymetry; endothelial cell density; contrast sensitivity; and ocular aberrations.At 6 months postoperatively, all 83 (100%) eyes had improved UNVA, with minimal or no change in UDVA. Twenty-two eyes were available at 12 months; UNVA improved to J1 in these eyes with continued improvement in mean UDVA. At last follow-up, a mild myopic shift in refraction was noted with only 3 (3.6%) eyes showing a 2- or 3-line decrease of UDVA, and 74 (89.2%) eyes achieved both J2 and 20/25 or better. Mean CDVA and distance corrected near visual acuity continued to improve with time. Two (2.4%) eyes lost 2 lines of CDVA at 6 months, but this did not occur in the 22 eyes seen at 1 year. Overall stability was noted in CH, CRF, pachymetry, endothelial cell density, and contrast sensitivity. Primary spherical aberrations shifted toward negative values and secondary spherical aberration shifted toward positive values. No corneal structural complications were observed.The INTRACOR intrastromal procedure using the TECHNOLAS femtosecond laser is a promising procedure for presbyopia correction. It preserves the corneal epithelium and anterior stromal fibers.

von Jagow B., Kohnen T.

To assess and compare the morphology of laser in situ keratomileusis flaps (LASIK) created by a 60 kHz femtosecond laser and a mechanical microkeratome.Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.Anterior segment optical coherence tomography (AS-OCT) (Visante) was used to assess 1 week postoperatively the morphology of 20 LASIK flaps created with the IntraLase femtosecond laser or the Zyoptix XP microkeratome. The flap diameter and flap thickness were assessed at 20 measuring points across each flap. First, the repeatability of the AS-OCT flap measurement was evaluated. On this basis, the dimensions of femtosecond laser flaps and microkeratome flaps were tested and their regularity, reproducibility, and accuracy compared.The method was approved with a repeatability of maximum 8.9 mum. The femtosecond laser flaps were more regular than the microkeratome flaps (P = .02). The reproducibility of flap morphology was not different in the central 1.0 mm radius area (P = .26); however, the femtosecond laser was significantly more precise than the microkeratome in the peripheral area (P = .001). The mean thickness of the femtosecond laser flap was significantly more accurate than the mean thickness of the microkeratome flap (P = .01), with a mean deviation of +16.9 mum and 40.8 mum, respectively.The flap architecture created with the femtosecond laser was more regular and accurate than the flap architecture created with the microkeratome.

Sekundo W., Kunert K., Russmann C., Gille A., Bissmann W., Stobrawa G., Sticker M., Bischoff M., Blum M.

To prospectively study the feasibility of femtosecond lenticule extraction (FLE), a new method of refractive correction.Department of Ophthalmology, Philipps University of Marburg and Helios Clinic, Erfurt, Germany.A flap and a lenticule of intrastromal corneal tissue were simultaneously cut with a VisuMax femtosecond laser system. Next, the lenticule was manually removed and the flap repositioned. The target refraction in all cases was -0.75 diopter (D).All 10 myopic eyes in the initial treatment group completed the final 6-month follow-up. The mean patient age was 39 years. The mean spherical equivalent (SE) was -4.73 +/- 1.48 (SD) preoperatively and -0.33 +/- 0.61 D 6 months postoperatively. Ninety percent of eyes were within +/-1.00 D and 40% were within +/-0.50 D of the intended correction. No eye lost 2 or more Snellen lines. Corneal topography showed large, prolate optical zones. Aberrometry showed no significant induction of higher-order aberrations. On a standardized questionnaire, all patients said they were very satisfied with the results.Preliminary results indicate that FLEx [corrected] is a promising new corneal refractive procedure to correct myopia.

Seider M.I., Ide T., Kymionis G.D., Culbertson W.W., O'Brien T.P., Yoo S.H.

We report the clinical manifestations and outcomes in 4 patients who experienced premature gas-bubble leakage during raster lamellar dissection during IntraLase femtosecond laser corneal flap creation. Three patients experienced a full-thickness epithelial breakthrough and the fourth, a flap tear. The patient who experienced the flap tear was unable to have laser in situ keratomileusis successfully. The flap complications did not result in a decreased best corrected visual acuity in any patient but may have resulted in epithelial ingrowth in one and a corneal scar and microstriae in another. Potential predisposing factors for epithelial breakthrough, the incidence of epithelial breakthrough, and methods for avoiding and salvaging traumatic corneal flaps are discussed.

Binder P.S.

To examine a database of laser in situ keratomileusis (LASIK) procedures for preoperative and operative factors assumed to increase the risk for developing post-LASIK ectasia.Private clinical practice.A computer database was queried for eyes that had LASIK for myopic refractive errors with the following characteristics: preoperative corneal thickness 500 microm or less, mean keratometry greater than 47.0 diopters (D), patient age 25 years or younger, attempted correction greater than -8.0 D, refractive astigmatism not with-the-rule and greater than 2.0 D, and residual stromal bed thickness (RST) 250 microm or less. Flap thickness and RST were measured using ultrasound pachymetry. All recorded information was exported to MS Excel and analyzed for eyes that had ectasia.Of the 9700 eyes in the database, none with the above characteristics developed ectasia over mean follow-up periods exceeding 2 years. Seven eyes had multiple risk factors without ectasia. Three eyes with abnormal preoperative topography developed ectasia.Individual preoperative and operative factors did not in and of themselves increase the risk for ectasia. Unmeasured and unknown factors that affect the individual cornea's biomechanical stability, in combination with some suspected risk factors as well as the current inability to identify corneas at risk for developing ectatic disorders, probably account for most eyes that develop ectasia today.

Steinert R.F., Ignacio T.S., Sarayba M.A.

To determine the feasibility of using a modified femtosecond laser to perform penetrating corneal resections.Controlled laboratory study.Fourteen corneoscleral rims were mounted on an artificial anterior chamber. Eight underwent traditional penetrating keratoplasty (PKP) and six underwent "top hat"-shaped PKP using a femtosecond laser. Wound leakage pressure and induced astigmatism were compared between the two groups.Deep corneal resection with the femtosecond laser was feasible. Wound leakage occurred at 38 +/- 11 mm Hg in the traditional PKP eyes and at 240 +/- 69 mm Hg in the laser-shaped PKP groups. Initial induced astigmatism was 3.76 +/- 0.82 diopters and 3.46 +/- 1.36 diopters in the traditional and shaped PKP groups, respectively.Shaped PKP using the femtosecond laser is feasible and provides superior incision integrity compared to traditional PKP. Initial induced astigmatism is dominated by suture effects.

Ertan A., Kamburoğlu G.

To analyze the centration of intrastromal ring segments (Intacs, Addition Technology, Inc.) implanted using a femtosecond laser in eyes with keratoconus.Kudret Eye Hospital, Ankara, Turkey.In a retrospective noncomparative case series, the distance of deviation of the intrastromal ring segment from the pupillary center was evaluated in 59 eyes of 39 keratoconic patients after tunnel creation with a femtosecond laser. The distance of deviation of segments from the pupillary edge and direction of decentration were analyzed using the anterior segment analyzer of the Pentacam Scheimpflug photographic camera (Oculus Opticgerate GmbH).Intacs were successfully implanted in all eyes. The mean horizontal deviation was 788.33 microm +/- 500.34 (SD) (range 30 to 2450 microm), and there was a temporal displacement in all eyes. The mean vertical deviation was 370.83 +/- 343.17 microm (range 0 to 1690 microm), and there was an inferior displacement in 28.81% of eyes and superior displacement in 66.10% of eyes. There was no vertical displacement in 3 eyes (5.08%).During applanation for Intacs correction by a femtosecond laser, the cornea and pupil are not in their natural position, which leads to decentration and misalignment of the segments.

Barraquer J.I.

Binder P.S.

To measure laser in situ keratomileusis (LASIK) flap dimensions created with the IntraLase FS (IL) laser (Intralase Corporation).Private practice, San Diego, California, USA.Consecutive LASIK flaps created with the IL were measured with subtraction ultrasound at primary and enhancement surgeries. Data were stored in Outcomes Analysis Software and analyzed using MS Excel (Microsoft Corporation) and SSPS software.The mean achieved flap thickness exceeded the attempted by 9.4 to 34.3 mum. The standard deviation varied from +/-10.2 to +/-21.7 mum. Preoperative corneal thickness and power did not affect achieved flap thickness. Seventy-three percent of mate eye flaps were within +/-15 mum of each other for the 90 mum attempted. The same flaps measured at enhancement were thicker than the primarily measured flaps (n = 58). Diffuse lamellar keratitis and slipped flaps were eliminated with experience. There were no decentered or irregular flaps, epithelial defects, or flap perforations.Compared with published results of mechanical microkeratomes, the IL reduced the standard deviation of flap thickness as well as the achieved range. It eliminated physical complications associated with mechanical flap creation, and the impact of preoperative pachymetry and corneal power, thereby permitting more myopia to be corrected without risking deep ablations.

Stonecipher K.G., Dishler J.G., Ignacio T.S., Binder P.S.

To describe the constellation of subjective and objective findings associated with unusual occurrences of photosensitivity after laser in situ keratomileusis (LASIK) with femtosecond flap creation and identify optimal management strategies.Demographic data, laser settings, subjective complaints, clinical findings, treatment, and response to treatment were recorded for suspected cases of transient postoperative photosensitivity from 3 surgeons operating at 3 different sites. All cases were estimated for the period covering the suspected cases at each site to assess incidence. Additional cases were solicited from IntraLase users via a survey.For the 3 sites, 63 eyes from 33 patients were reported of a total estimated case log of 5667 (incidence, 1.1%). Average age was 41 years, and 51.7% of patients were women. Onset of symptoms ranged from 2 to 6 weeks after uneventful LASIK. All patients were treated with prednisolone acetate drops, whereas 1 surgeon also used Restasis (cyclosporine ophthalmic solution 0.05%). Patients noted improvement of symptoms within 1 week of treatment. When the raster and side-cut energy settings were lowered (by an average of 24% and 33%, respectively), significant reductions in incidence were noted. Similar findings were reported by 3 additional surgeons reporting 17 cases in the survey of IntraLase users.This report describes a new complication of LASIK performed with a femtosecond laser keratome that may be related to the pulse energy used for flap creation. Although there is no loss of uncorrected visual acuity, symptoms can be prolonged, especially without prompt steroid therapy. Technical advances that reduced pulse energies appear to decrease the incidence.

Tran D.B., Sarayba M.A., Bor Z., Garufis C., Duh Y., Soltes C.R., Juhasz T., Kurtz R.M.

To measure and compare the changes in objective wavefront aberration and subjective manifest refraction after laser in situ keratomileusis (LASIK) flap creation with a mechanical microkeratome and a femtosecond laser.Private practice refractive surgery center, Irvine, California, USA.This randomized prospective study comprised 9 patients (18 eyes) treated with a 2-step LASIK procedure: lamellar keratectomy with a Hansatome microkeratome (Bausch & Lomb) or the IntraLase femtosecond laser in fellow eyes followed by non-wavefront-guided (standard) excimer laser treatment with the Technolas 217A (Bausch & Lomb) excimer laser 10 weeks later. Fellow eyes were matched to within 0.75 diopter (D) sphere and 0.50 D cylinder. Patients were followed for 3 months after excimer laser treatment. Preoperative and post-flap creation wavefront aberrometry using a Hartmann-Shack aberrometer and manifest refraction were compared between the 2 groups. The same tests were performed 3 months after excimer laser ablation.Statistically significant changes were seen in defocus wavefront aberrations after Hansatome (P=.004) and IntraLase (P=.008) flap creation. A hyperopic shift in manifest refraction was noted in the Hansatome group after the creation of the corneal flap (P=.04); no statistically significant changes in manifest refraction were seen in the IntraLase group. Statistically significant changes in total higher-order aberrations (HOAs) (trefoil and quadrafoil Zernike terms) were seen after flap creation in the Hansatome group (P=.02). No significant changes in HOAs were noted after flap creation in the IntraLase group. After the flap was relifted and standard excimer laser ablation was performed, a statistically significant increase in coma occurred in the Hansatome group (P=.008). Standard refractive outcomes in the 2 groups were similar.The creation of the LASIK flap alone can modify the eye's optical characteristics in low-order aberrations and HOAs. A significant increase in HOAs was seen in the Hansatome group but not in the IntraLase group. This may have significant clinical implications in wavefront-guided LASIK treatments, which are based on measurements made before flap creation.

Sandoval H.P., de Castro L.E., Vroman D.T., Solomon K.D.

To determine the refractive surgery (RS) preferences of ophthalmologists worldwide, questionnaires were sent to 8897 members of the American Society of Cataract and Refractive Surgery. A total of 1053 questionnaires were returned by the deadline. The practice distribution included 29.5% cataract surgeons, 48.8% comprehensive ophthalmologists, 11.6% RS specialists, 5.1% cornea and external disease specialists, 1.9% glaucoma specialists, 1.1% retina specialists, and

Walter K.A., Stevenson A.W.

To determine whether environmental factors affect laser in situ keratomileusis (LASIK) enhancement rates.Wake Forest University Eye Center, Winston-Salem, North Carolina, USA.This retrospective chart review comprised 368 consecutive eyes of 191 myopic patients who had LASIK by the same surgeon (K.A.W.). All patients had surgery in 2000 with the Visx Star S2 excimer laser. Refractive outcome, visual acuity, and enhancement rates were monitored closely for 1 year. Fifty-seven eyes (15.5%) had an enhancement procedure. Using enhancement procedure or percentage of correction as the outcome measure, factors that were suspected to affect LASIK results and the need for enhancement were examined; specifically, age, eye, sex, pachymetry, corneal curvature (K), preoperative spherical equivalent, ablation depth, and environmental factors (procedure room temperature, procedure room relative humidity, outdoor temperature, and outdoor relative humidity).Using univariate and multivariate analysis, LASIK enhancement rates strongly correlated with the following variables: procedure room humidity (P =.003; odds ratio [OR] = 1.093; 95% confidence intervals [CI], 1.030-1.160), 2-week preoperative mean outdoor humidity (P =.011; OR = 1.054; 95% CI, 1.012-1.096), outdoor temperature (P =.0059; OR = 1.039; 95% CI, 1.011-1.068), and age (P =.0497; OR = 1.034; 95% CI, 1.001-1.070). The percentage of correction strongly correlated with the following variables: procedure room humidity (P =.021), 2-week preoperative mean outdoor humidity (P =.001), outdoor temperature (P =.0052), and room temperature (P =.017).The 2-week-preoperative mean outdoor relative humidity, procedure room relative humidity, outdoor temperature, and procedure room temperature may have to be considered during LASIK planning. The effect of these environmental variables on LASIK outcomes warrants further evaluation.

Binder P.S.

Eighty-five cases of post laser in situ keratomileusis ectasia were reviewed and analyzed. Cases of keratoconus or forme fruste keratoconus were eliminated; many remaining case reports lacked key information. The current literature is unable to define a specific residual corneal thickness or a range of preoperative corneal thickness that would put an eye at risk for developing ectasia. The most logical cause for eyes without preexisting pathology to develop ectasia is a postablation stromal thickness that is mechanically unstable; this "minimal" thickness is probably specific to each eye. The preoperative and postoperative corneal thickness, measured flap thickness, and microkeratome and laser parameters used in a given case are required to determine the range of residual corneal thickness that puts the eye at risk for developing ectasia. Other as yet undetermined factors may play a role in the development of this complication.

Zheng Y., Zhou Y., Zhang J., Liu Q., Zhang L., Deng Z., Li S.

To compare the mesopic contrast sensitivity (CS) and higher order aberrations (HOAs) at 3 months after femtosecond-laser in situ keratomileusis (LASIK) (FS-LASIK), wave front-guided femtosecond LASIK (WF-LASIK), and femtosecond lenticule extraction (FLEx) for the correction of myopia and myopic astigmatism.In this prospective nonrandomized study, 332 right eyes of 332 patients were treated with FS-LASIK, WF-LASIK, or FLEx. The HOAs and mesopic CS were evaluated preoperatively and at 3 months postoperatively.At 3 months of follow-up, 98 eyes (96.1%) of the FS-LASIK group, 92 eyes (98.9%) of the WF-LASIK group, and 133 eyes (96.4%) of the FLEx group had an uncorrected distance visual acuity of 20/20 or better. The HOAs improved from 0.34 μm during preoperative examination to 0.56 μm of the end of the follow-up in the FS-LASIK group, from 0.31 to 0.41 μm in the WF-LASIK group, and from 0.32 to 0.54 μm in the FLEx group (all P < 0.01). At a spatial frequency of 12 cycles per degree, a better mesopic CS was observed in the WF-LASIK group (1.47) than in the FS-LASIK (1.36) and FLEx (1.33) groups (P < 0.01); a better mesopic CS with glare was also noted in the WF-LASIK group (1.37) than in the FS-LASIK (1.25) and FLEx (1.29) groups (P < 0.01).The FS-LASIK, WF-LASIK, and FLEx procedures result in comparable refractive results at 3 months postoperatively. However, there is improvement in the mesopic CS and HOAs after WF-LASIK.

Yao P., Zhao J., Li M., Shen Y., Dong Z., Zhou X.

To study microdistortions in Bowman's layer after femtosecond laser small incision lenticule extraction (SMILE) using Fourier-domain optical coherence tomography (OCT) and to investigate possible sources and potential visual impacts.A nonrandomized controlled prospective study enrolled 52 eyes of 29 consecutive patients undergoing SMILE, with spherical equivalent of -6.33 ± 1.88 diopters and 4.2 mm superior incision. The microdistortions in Bowman’s layer were counted at 1 day, 1 week, and 1 month postoperatively and at long-term follow-up. Another 38 eyes of 20 patients undergoing femtosecond laser-assisted LASIK (FS-LASIK) were examined at 1 day and long-term postoperatively as the control group.Microdistortions in Bowman’s layer were observed by OCT, with no clinically significant corneal striae under slit-lamp microscopy, in 46 eyes (88.5%) on day 1 after SMILE and in 16 eyes (42.1%) after FS-LASIK, with more in SMILE eyes than in FS-LASIK eyes. The amount decreased at 1 week and then remained stable. There were more microdistortions in the center area than in the periphery in both groups. Microdistortions were more in the inferior than the superior quadrant on the first day after SMILE but there was no difference at long-term follow-up. Microdistortions after SMILE were associated with the refractive lenticule thickness and surgery order but had no significant impact on long-term visual outcomes or wavefront aberrations.Microdistortions in Bowman's layer after SMILE were associated with the refractive lenticule thickness and surgery order. The microdistortions remained stable after 1 week and had no impact on long-term visual performance.