Therapeutic Femtosecond Laser-Assisted Lamellar Keratectomy for Multidrug-Resistant Nocardia Keratitis.

PURPOSE: To describe the novel use of femtosecond laser technology for therapeutic resection of infectious foci in a case of multidrug-resistant Nocardia asteroides keratitis. METHODS: A 30-year-old man presented with a corneal infiltrate. Cultures were taken, and fortified vancomycin and tobramycin were initiated. After 3 negative cultures and minimal improvement on various broad-spectrum antibiotics, all topical medications were stopped and a final fourth corneal culture grew N. asteroides. Treatment with topical amikacin was initiated, but the infection continued to worsen. With drug sensitivities still pending, the patient's clinical status continued to deteriorate rapidly, despite treatment with amikacin, gatifloxacin, and polymyxin B/trimethoprim. The femtosecond laser was then used to perform targeted lamellar keratectomy. RESULTS: Femtosecond laser-assisted lamellar keratectomy successfully removed the infected tissue and allowed for increased penetration of topical antibiotics. Drug sensitivities finally returned, revealing multidrug resistance and sensitivity only to trimethoprim/sulfamethoxazole and tobramycin, some of which the patient had previously tried and failed. The infection fully resolved after readministering polymyxin B/trimethoprim and tobramycin, leaving minimal residual scarring. CONCLUSIONS: Multidrug-resistant N. asteroides keratitis can be difficult to manage even with appropriate antibiotic therapy based on drug sensitivity testing. Femtosecond laser-assisted resections may facilitate treatment in these cases by safely and precisely debulking infected tissue and enhancing penetration of topical medications.

Femtosecond laser-assisted cataract surgery in a patient with posterior chamber phakic intraocular lens.

We describe a case of modified femtosecond laser settings for cataract extraction in a patient with a posterior chamber phakic intraocular lens (PIOL), to avoid incomplete treatment patterns and treatment displacement. Modification of laser settings (increased depth for the capsulotomy, increased vertical spot spacing for the capsulotomy and increased anterior and posterior capsule safety margins for lens fragmentation) seems to make femtosecond laser-assisted cataract surgery feasible in patients with posterior chamber PIOLs, as complete treatment patterns are achieved.

Calculation of ophthalmic viscoelastic device-induced focus shift during femtosecond laser-assisted cataract surgery.

PURPOSE: To assess if a change in refractive index of the anterior chamber during femtosecond laser-assisted cataract surgery can affect the laser beam focus position. METHODS: The index of refraction and chromatic dispersion of six ophthalmic viscoelastic devices (OVDs) was measured with an Abbe refractometer. Using the Gullstrand eye model, the index values were used to predict the error in the depth of a femtosecond laser cut when the anterior chamber is filled with OVD. Two sources of error produced by the change in refractive index were evaluated: the error in anterior capsule position measured with optical coherence tomography biometry and the shift in femtosecond laser beam focus depth. RESULTS: The refractive indices of the OVDs measured ranged from 1.335 to 1.341 in the visible light (at 587 nm). The error in depth measurement of the refilled anterior chamber ranged from -5 to +7 µm. The OVD produced a shift of the femtosecond laser focus ranging from -1 to +6 µm. Replacement of the aqueous humor with OVDs with the densest compound produced a predicted error in cut depth of 13 µm anterior to the expected cut. CONCLUSIONS: Our calculations show that the change in refractive index due to anterior chamber refilling does not sufficiently shift the laser beam focus position to cause the incomplete capsulotomies reported during femtosecond laser-assisted cataract surgery.

Operating times of experienced cataract surgeons beginning femtosecond laser-assisted cataract surgery.

PURPOSE: To compare the time a patient spent in the operating room during femtosecond laser-assisted with that during traditional cataract surgery. SETTING: Academic tertiary referral center. DESIGN: Retrospective review. METHODS: Data from 3 attending surgeons who operated in the room that housed the femtosecond laser were collected from the first 6 months of the femtosecond laser's use. The time in the operating room was measured from when the patients entered the room to the time they left. Traditional-approach cases done in the room were compared with cases performed using the femtosecond laser (Catalys Precision Laser System). RESULTS: During the first 6 months, 420 cataract cases were performed in the operating room housing the femtosecond laser; the femtosecond laser was used in 162 cases (38.6%). Femtosecond laser-assisted surgeries were 11.1 to 12.1 minutes longer than traditional surgeries (P<.0001). When only routine cases were included in the comparison, the femtosecond laser-assisted approach remained 11.6 to 13.4 minutes longer (P<.0001). CONCLUSION: The additional steps required to perform femtosecond laser-assisted cataract surgery resulted in a statistically significant longer time per case than the time required with a traditional approach. FINANCIAL DISCLOSURES: Dr. Culbertson is a consultant to Abbott Medical Optics, Inc., and Optimedica Corp. Dr. Yoo is a consultant to Alcon Laboratories, Inc., and Abbott Medical Optics, Inc.. No other author has a financial or proprietary interest in any material or method mentioned.

Avoiding Negative Dysphagia Outcomes.

Dysphagia in adults affects their quality of life and can lead to life-threatening conditions. The authors draw on both 30 years of experience as clinicians and also on expert testimony in adult, dysphagia-malpractice cases to make five recommendations with the aim of preventing dysphagia-related deaths. They discuss the importance of informed consent documents and suggest the following nursing actions to reduce these often unnecessary tragedies: consider the importance of diet status; understand and follow speech-language-pathologists' recommendations; be familiar with the dysphagia assessment; be responsive to the need for an instrumental assessment; and ensure dysphagia communication is accurate and disseminated among healthcare professionals. They conclude that most negative dysphagia-management outcomes can be prevented and that nurses play a pivotal role in this prevention.

Femtosecond laser-assisted technique for performing bag-in-the-lens intraocular lens implantation.

We describe a technique for femtosecond laser-assisted bag-in-the-lens (BIL) intraocular lens (IOL) implantation. Anterior capsulotomy and lens division into small pieces are performed by the laser. A fluid-filled interface makes it possible to re-dock the laser to the eye for posterior capsulotomy after the eye has been opened for lens aspiration without complications. The integrated optical coherence tomography also visualizes the posterior capsule, allowing a centered central posterior capsulotomy for uncomplicated IOL positioning. In 31 patients, no complications were observed within a 1-month follow-up. Femtosecond laser-assisted cataract surgery facilitated the BIL technique.

Comparison of IOL power calculation methods and intraoperative wavefront aberrometer in eyes after refractive surgery.

PURPOSE: To compare preoperative methods for calculating intraocular lens (IOL) power versus the intraoperative wavefront aberrometer in eyes with a history of refractive surgery. METHODS: A retrospective study of 46 eyes (33 patients) with previous refractive surgery that underwent subsequent cataract surgery was conducted. Suggested IOL power predicted by ORange intraoperative wavefront aberrometer (WaveTec Vision Systems, Inc., Aliso Viejo, CA) was compared to power predicted by the (1) SRK-T formula using keratometry and axial length measurements from the IOLMaster (Carl Zeiss Meditec, Dublin, CA), (2) average central keratometry (Avg K) from corneal topography, and (3) average IOL power predicted by the American Society of Cataract and Refractive Surgery (ASCRS) web site. No historical information was used for the calculations. IOL power required for emmetropia was back-calculated using manifest refraction and implanted IOL power after cataract surgery. RESULTS: Mean age was 60 ± 7.9 years. Fifteen percent had a history of myopic photorefractive keratectomy (n = 7), 57% myopic LASIK (n = 26), 13% hyperopic LASIK (n = 6), and 22% radial keratectomy (RK) (n = 10). In 37% of cases, ORange predicted IOL power to within ±0.50 diopters (D) of emmetropia, compared to 30% for IOLMaster keratometry, 26% for Avg K, and 17% for ASCRS web site. In eyes after myopic treatment, ORange, IOLMaster, Avg K, and ASCRS web site predicted within ±0.50 D of emmetropia in 39%, 27%, 24%, and 18%, respectively, and within ±1.0 D in 60%, 39%, 39%, and 51%, respectively. In eyes after RK, ORange, Avg K, and ASCRS web site predicted to within ±0.50 D of emmetropia in 14% and the IOLMaster in 43% cases. CONCLUSIONS: Although the ORange most often predicted to within ±0.5 D of emmetropia, no method was able to achieve this accuracy more than 50% of the time. Predictions for eyes after RK were worse than for other types of refractive procedures.

Complications of femtosecond laser-assisted re-treatment for residual refractive errors after LASIK.

PURPOSE: To report complications of femtosecond laser-assisted re-treatment by the creation of side cuts within the old flaps for residual refractive error after primary LASIK in two patients. METHODS: Case report. RESULTS: Three eyes of two patients had complications with a circumferential sliver of stromal tissue displaced during surgery due to overlap of old and new side cuts. The displaced tissue was repositioned and corneal anatomy was restored. Two of three eyes demonstrated improvement in the uncorrected visual acuity, whereas one eye lost two lines of corrected visual acuity due to loss of tissue at side cut resulting from flap manipulation, which was done at 1 week. CONCLUSIONS: These cases demonstrate a complication of femtosecond laser-enabled side-cut for LASIK enhancement and factors that may lead to this complication and precautions to avoid it.

Femtosecond laser-assisted retreatment for residual refractive errors after laser in situ keratomileusis.

PURPOSE: To study the utility of creating an additional side cut within the old laser in situ keratomileusis (LASIK) flap using a femtosecond laser to reduce the incidence of epithelial ingrowth in patients having retreatments for residual refractive errors after LASIK. SETTING: Bascom Palmer Eye Institute, Miller School of Medicine, Miami, Florida, USA. DESIGN: Comparative case series. METHODS: On a chart review of all cases that had retreatment between January 2004 and April 2011, eyes in which an additional side cut with the femtosecond laser within the old LASIK flap margin was created were classified as Group 1. All eyes having retreatment using traditional flap-relifting techniques between January 2008 and April 2011 were classified as Group 2. RESULTS: Twenty-four eyes of 18 patients had femtosecond laser-assisted retreatment with side cut only (Group 1), while 103 eyes of 80 patients had a flap-lift LASIK enhancement (Group 2). Twenty-seven cases of epithelial ingrowth were identified in the 2 groups, 4 cases (17%) in the side-cut group and 23 cases (22%) in the flap-lift group. There was a statistically significant difference between the 2 groups in the incidence of epithelial ingrowth in patients in which the microkeratome was used as the initial method of flap creation (P<.05). CONCLUSION: Femtosecond laser-assisted side-cut LASIK resulted in a statistically significant lower incidence of epithelial ingrowth after stratification because of the higher risk for epithelial ingrowth in patients who had primary LASIK with microkeratome flaps.

Sources of medical error in refractive surgery.

PURPOSE: To evaluate the causes of laser programming errors in refractive surgery and outcomes in these cases. METHODS: In this multicenter, retrospective chart review, 22 eyes of 18 patients who had incorrect data entered into the refractive laser computer system at the time of treatment were evaluated. Cases were analyzed to uncover the etiology of these errors, patient follow-up treatments, and final outcomes. The results were used to identify potential methods to avoid similar errors in the future. RESULTS: Every patient experienced compromised uncorrected visual acuity requiring additional intervention, and 7 of 22 eyes (32%) lost corrected distance visual acuity (CDVA) of at least one line. Sixteen patients were suitable candidates for additional surgical correction to address these residual visual symptoms and six were not. Thirteen of 22 eyes (59%) received surgical follow-up treatment; nine eyes were treated with contact lenses. After follow-up treatment, six patients (27%) still had a loss of one line or more of CDVA. Three significant sources of error were identified: errors of cylinder conversion, data entry, and patient identification error. CONCLUSION: Twenty-seven percent of eyes with laser programming errors ultimately lost one or more lines of CDVA. Patients who underwent surgical revision had better outcomes than those who did not. Many of the mistakes identified were likely avoidable had preventive measures been taken, such as strict adherence to patient verification protocol or rigorous rechecking of treatment parameters.

Optical patient interface in femtosecond laser-assisted cataract surgery: contact corneal applanation versus liquid immersion.

PURPOSE: To compare 2 optical patient interface designs used for femtosecond laser-assisted cataract surgery. SETTING: Optimedica Corp., Santa Clara, California, USA, and Centro Laser, Santo Domingo, Dominican Republic. DESIGN: Experimental and clinical studies. METHODS: Laser capsulotomy was performed during cataract surgery with a curved contact lens interface (CCL) or a liquid optical immersion interface (LOI). The presence of corneal folds, incomplete capsulotomy, subconjunctival hemorrhage, and eye movement during laser treatment were analyzed using video and optical coherence tomography. The induced rise of intraocular pressure (IOP) was measured in porcine and cadaver eyes. RESULTS: Corneal folds were identified in 70% of the CCL cohort; 63% of these had areas of incomplete capsulotomies beneath the corneal folds. No corneal folds or incomplete capsulotomies were identified in the LOI cohort. The mean eye movement during capsulotomy creation (1.5 sec) was 50 µm with a CCL and 20 µm with an LOI. The LOI cohort had 36% less subconjunctival hemorrhage than the CCL cohort. During suction, the mean IOP rise was 32.4 mm Hg ± 3.4 (SD) in the CCL group and 17.7 ± 2.1 mm Hg in the LOI group. CONCLUSIONS: Curved contact interfaces create corneal folds that can lead to incomplete capsulotomy during laser cataract surgery. A liquid interface eliminated corneal folds, improved globe stability, reduced subconjunctival hemorrhage, and lowered IOP rise.

Quality of corneal lamellar cuts quantified using atomic force microscopy.

PURPOSE: To quantify the cut quality of lamellar dissections made with the femtosecond laser using atomic force microscopy (AFM). SETTING: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. DESIGN: Experimental study. METHODS: Experiments were performed on 3 pairs of human cadaver eyes. The cornea was thinned to physiologic levels by placing the globe, cornea side down, in 25% dextran for 24 hours. The eyes were reinflated to normal pressures by injecting a balanced salt solution into the vitreous cavity. The eyes were placed in a holder, the epithelium was removed, and the eyes were cut with a Visumax femtosecond laser. The energy level was 180 nJ for the right eye and 340 nJ for the left eye of each pair. The cut depths were 200 µm, 300 µm, and 400 µm, with the cut depth maintained for both eyes of each pair. A 12.0 mm trephination was then performed. The anterior portion of the lamellar surface was placed in a balanced salt solution and imaged with AFM. As a control, the posterior surface was placed in 2% formalin and imaged with environmental scanning electron microscopy (SEM). Four quantitative parameters (root-mean-square deviation, average deviation, skewness, kurtosis) were calculated from the AFM images. RESULTS: From AFM, the 300 µm low-energy cuts were the smoothest. Similar results were seen qualitatively in the environmental SEM images. CONCLUSION: Atomic force microscopy provided quantitative information on the quality of lamellar dissections made using a femtosecond laser, which is useful in optimizing patient outcomes in refractive and lamellar keratoplasty surgeries.

Epithelial ingrowth after LASIK: clinical characteristics, risk factors, and visual outcomes in patients requiring flap lift.

PURPOSE: To describe clinical characteristics, risk factors, and visual outcomes in patients requiring flap lift for epithelial ingrowth following LASIK. METHODS: Consecutive, noncomparative, retrospective case series of eyes requiring flap lift for epithelial ingrowth following LASIK from June 2003 through July 2011 at a tertiary care, university-based eye hospital. Main outcome measures were uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) at 1 and 3 months and recurrence of epithelial ingrowth. RESULTS: Forty-five eyes were included. Laser in situ keratomileusis retreatment was the most common etiologic factor for epithelial ingrowth (28/45 eyes [62%]). All patients were treated with flap lift and scraping. Mean logMAR UDVA at presentation was 0.28 (Snellen equivalent 20/38). Mean logMAR UDVA at 3 months was 0.17 (Snellen equivalent 20/30) with 53% of eyes 20/25 or better. Mean logMAR CDVA at 3 months was 0.06 (Snellen equivalent 20/23) with 78% of eyes 20/25 or better. Epithelial ingrowth into the central cornea portended a trend towards UDVA worse than 20/25 or worse at 3-month follow-up (hazard ratio [HR] 5.54, 95% confidence interval [CI]: 0.98-31.3, P=.05) and CDVA worse than 20/25 at 3-month follow-up (HR 4.32, 95% CI: 0.85-21.9, P=.08). Recurrence after treatment was 31% at 3 months and 36% at 1 year. Risk factors for recurrence included: infectious etiology of ingrowth (HR 5.7, 95% CI: 1.11-29.1, P=.04), use of microkeratome for primary LASIK (HR 4.64, 95% CI: 1.07-20.1, P=.04), and hyperopic primary LASIK (HR 2.49, 95% CI: 0.98-6.31, P=.06). CONCLUSIONS: Patients undergoing flap lift for the treatment of epithelial ingrowth have a relatively high rate of recurrence but good visual acuity outcomes.

Protective effect of LASIK flap in penetrating keratoplasty following blunt trauma.

Penetrating keratoplasty (PKP) often results in large and unpredictable refractive errors following suture removal in the postoperative period. Laser in situ keratomileusis (LASIK) is an effective means of correcting these errors. However, LASIK following PKP is believed to further weaken an already weak graft-host junction and may predispose such eyes to traumatic dehiscence of the graft-host junction. We describe a case in which the LASIK surgery following PKP seemed to benefit the patient by preventing complete dehiscence of the graft-host junction.

Femtosecond laser capsulotomy.

PURPOSE: To evaluate a femtosecond laser system to create the capsulotomy. SETTING: Porcine and cadaver eye studies were performed at OptiMedica Corp., Santa Clara, California, USA; the human trial was performed at the Centro Laser, Santo Domingo, Dominican Republic. DESIGN: Experimental and clinical study. METHODS: Capsulotomies performed by an optical coherence tomography-guided femtosecond laser were evaluated in porcine and human cadaver eyes. Subsequently, the procedure was performed in 39 patients as part of a prospective randomized study of femtosecond laser-assisted cataract surgery. The accuracy of the capsulotomy size, shape, and centration were quantified and capsulotomy strength was assessed in the porcine eyes. RESULTS: Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 µm ± 26 (SD) for the laser technique and 337 ± 258 µm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 ± 47 µm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 ± 21 mN for 3 µJ, 121 ± 16 mN for 6 µJ, and 113 ± 23 mN for 10 µJ. The strength of the manual capsulorhexes was 65 ± 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique.

Long-term results of femtosecond laser-assisted sutureless anterior lamellar keratoplasty.

PURPOSE: To evaluate the long-term results of femtosecond laser-assisted anterior lamellar keratoplasty (FALK) for anterior corneal pathologies. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Thirteen consecutive patients who underwent FALK for anterior corneal pathologies. INTERVENTION: Femtosecond laser-assisted sutureless anterior lamellar keratoplasty. MAIN OUTCOME MEASURES: Best spectacle-corrected visual acuity (BSCVA), manifest refraction, need for adjunctive surgery, and complications. RESULTS: Follow-up ranged from 12 to 69 months (mean = 31 months). The BSCVA was significantly improved over preoperative values at the 12-, 18-, 24-, and 36-month visits. A BSCVA greater than 20/30 was achieved in 54% of patients at the 12-month visit when all 13 patients were available for follow-up, in 50% and 33% of patients at the 18- and 24-month visits, respectively, when 12 patients were available, and in 60% and 50% of patients at the 36- and 48-month visits when 5 and 2 patients were available, respectively. The BSCVA of the eye that completed the 60- and 70-month visits was 20/50. Patients achieved a mean gain of 5 lines of BSCVA at the 6-, 12-, 18-, and 24-month visits, 4 lines at the 36-month visit, 5 lines at the 48-month visit, and 6 lines at the 60- and 72-month visits. Two patients lost a mean of 1.5 lines of BSCVA because surface haze developed after photorefractive keratectomy (PRK) and granular dystrophy recurred in the graft. At a mean of 5 weeks postoperatively, 83.3% of patients achieved BSCVA within 2 lines of that recorded at the 24-month visit. At the 12-month visit, mean spherical equivalent and refractive astigmatism were -0.4 diopters (D) and 2.2 D, respectively, with no significant shift from preoperative values or values recorded in different follow-up visits. Adjunctive surgeries included phototherapeutic keratectomy, PRK, cataract extraction, and epithelial ingrowth debridement. Complications included residual corneal pathology, mild interface haze, anisometropia, recurrence of pathology, haze after adjunctive PRK, dry eye, epithelial ingrowth, and suspicious ectasia. CONCLUSIONS: Femtosecond laser-assisted sutureless anterior lamellar keratoplasty improves the BSCVA of patients with anterior corneal pathologies with rapid visual rehabilitation and no significant induced astigmatism. Our preliminary results indicate that FALK results remained stable throughout the follow-up period.

Femtosecond laser-assisted cataract surgery.

PURPOSE OF REVIEW: In 2010, the US Food and Drug Administration (FDA) cleared femtosecond laser systems for cataract surgery. Available in 2011, this technology has the potential to significantly impact cataract surgery. RECENT FINDINGS: Femtosecond lasers offer surgeons the ability to make very precise cuts in a targeted area without damaging the surrounding tissues. This technology has already dramatically changed refractive surgery and is poised to do the same for cataract surgery. Three companies, OptiMedica, LenSx (acquired by Alcon in September 2010), and LensAR, in different stages of FDA clearance, are developing femtosecond laser systems for cataract surgery. These systems will create the initial corneal incisions, capsulotomy, and also fragment the lens. SUMMARY: This article outlines the advantages of femtosecond laser cataract surgery and provides an initial comparison of the LensAR, LenSx/Alcon, and OptiMedica systems and early clinical results.