Feasibility Study: Towards a Robot-Assisted Gait Training in Ophthalmological Rehabilitation.

The idea of using mobile assistance robots for gait training in rehabilitation has been increasingly explored in recent years due to the associated benefits. This paper describes how the previous results of research and praxis on gait training with a mobile assistance robot in orthopedic rehabilitation can be transferred to ophthalmic-related orientation and mobility training for blind and visually impaired people. To this end, the specific requirements for such orientation and mobility training are presented from a therapeutic perspective. Using sensory data, it is investigated how the analysis of training errors can be automated and transferred back to the training person. These pre-examinations are the prerequisite for any form of robot-assisted mobile gait training in ophthamological rehabilitation, which does not exist so far and which is expected to be of great benefit to these patients.

10-Year Results of FLEx Refractive Surgery.

PURPOSE: To evaluate the 10-year results of femtosecond lenticule extraction (FLEx) for treatment of myopia and myopic astigmatism. METHODS: This long-term follow-up of a prospective clinical trial was conducted at HELIOS Klinikum Erfurt and Phillips University of Marburg, Germany. In 2006, 108 eyes underwent the FLEx procedure. All patients were invited for reexamination 10 years after FLEx treatment for myopia and astigmatism. Visual acuity, objective and manifest refraction, intraocular pressure, and slit-lamp examination and side effects were documented. Main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuity, objective and manifest refraction, and slit-lamp examination and side effects. RESULTS: A total of 77 eyes of 40 patients of the original treatment group volunteered for a reexamination 10 years after surgery. The mean age of the patients was 45.9 years; 26 were women and 14 were men. UDVA was 0.09 ± 0.19 logMAR and CDVA was stable at -0.1 ± 0.09 logMAR. More than half of the eyes gained one or two Snellen lines, and none of the eyes lost two or more lines. Over the 10-year period, regression was 0.18 D. CONCLUSIONS: FLEx has stable results 10 years after treatment for myopia and astigmatism. [J Refract Surg. 2019;35(11):707-711.].

10-Year Results of Small Incision Lenticule Extraction.

PURPOSE: To evaluate the 10-year results of refractive lenticule extraction using the small incision lenticule extraction (SMILE) technique for treatment of myopia and myopic astigmatism. METHODS: In 2008-2009, the first 91 eyes were treated using a novel surgical technique (SMILE), in which a refractive lenticule of intrastromal corneal tissue is removed through a small incision, completely eliminating flap cutting. A total of 56 of 91 eyes of the original treatment group volunteered for reexamination 10 years after surgery, including uncorrected and corrected distance visual acuity, objective and manifest refraction, and evaluation of the interface and corneal surface by slit-lamp examination. Late side effects such as corneal scarring, corneal ectasia, persistent dry eye symptoms, or cataract were documented. RESULTS: At 10 years postoperatively, there was no significant change from the 6-month results. Spherical equivalent was -0.35 ± 0.66 diopters and therefore close to target refraction. Sixteen of the 56 eyes (29%) had gained one to two Snellen lines. There was no loss of two or more lines in the long term. Regression was -0.35 ± 0.66 diopters over the 10-year period. CONCLUSIONS: This 10-year long-term study demonstrates SMILE to be an effective, stable, and safe procedure for the treatment of myopia and myopic astigmatism. [J Refract Surg. 2019;35(10):618-623.].

[Retrospective Study of Long-term Patient Satisfaction after Bilateral Implantation of Multifocal Intraocular Lenses of Different Generations - a 10 Year Follow-up]. / Patientenzufriedenheit nach Implantation von Multifokallinsen verschiedener Generationen ­ ein 10-Jahres-Follow-up.

BACKGROUND: This retrospective study investigates the postoperative satisfaction of patients with a mixed generation background after bilateral implantation of non-toric multifocal intraocular lenses between the year 2006 and year 2017. PATIENTS/METHODS: 245 patients between 45 and 95 years old were included in the study. Patient satisfaction was examined with the Heidelberg DATE questionnaire (DATE: Daily Tasks Evaluation), with respect to everyday tasks and the perception of optical phenomena. All criteria of the questionnaire were assessed for significant differences with respect to the time of the operation, the age of the patient, gender as well as the model of the implanted intraocular lens. The data was analysed with the statistics software SPSS 23.0. RESULTS: At the time of the survey, 97.1% of patients reported they were completely or partially satisfied with the outcome of the operation. 95.9% of patients could accomplish all common tasks without any significant problems. 34.6% said they only needed glasses under very challenging visual circumstances. The older patients more often reported that they needed glasses (p < 0.01). Women wore glasses more frequently for driving during night than men. They also described dazzling as more disturbing (p < 0.03). Younger patients perceived halos more drastically than older patients (p < 0.01). Patients with bifocal lens implants used glasses for intermediary distances far more often than patients with trifocal implants (p < 0.01). CONCLUSION: Most patients were independent of additional optical correction. Optical phenomena are commonly reported, so extensive preoperative briefing is inevitable. The need for further information seems to be especially high among younger, female patients. The Heidelberg DATE questionnaire is well suited for surveying patient satisfaction after the implantation of multifocal intraocular lenses.

Interface morphology and gas production by a refractive 347 nm ultraviolet femtosecond laser: Comparison with established laser systems.

PURPOSE: To evaluate gas production and interface quality after refractive lenticule creation. A new ultraviolet (UV) 347 nm femtosecond laser was compared with the FS200 and the Visumax lasers. SETTING: Department of Anatomy II, University of Erlangen-Nürnberg, Erlangen, Germany. DESIGN: Experimental study. METHODS: Refractive lenticules were created in 52 porcine corneas with the UV laser (n = 20), the Visumax laser (n = 20), and a modified FS200 laser (n = 12). Twelve corneas in each laser group were fixed immediately after lenticule creation to entrap the gas produced. Lenticule extraction was omitted. From 16 other corneas (UV and Visumax lasers; n = 8 each) -5.0 diopter (D) and -10.0 D lenticules were extracted. On lenticule extraction, a flap was created and lifted. In 12 additional corneas, a flap was cut using the FS200 laser and lifted afterward; laser in situ keratomileusis was performed on 8 of these samples. The corneas were processed for light microscopy (gas bubble 2-dimensional morphometry) and scanning electron microscopy (interface quality). RESULTS: The Visumax generated approximately one half as much gas as the FS200. The UV laser undercut the Visumax by another 50%. The interfaces created by the FS200 appeared smooth and without irregularities. The optical zone margin was always conspicuous in the Visumax samples but hardly discernible in the UV specimens. Slight irregularities and very small lenticule pieces were found occasionally in both groups. The UV interfaces appeared slightly rougher than the Visumax interfaces. CONCLUSIONS: Ultraviolet laser lenticule extraction seems promising. The interface quality was similar to that of the clinical Visumax system while gas production was reduced significantly.

Influence of the beam profile crosslinking setting on changes in corneal topography and tomography in progressive keratoconus: Preliminary results.

PURPOSE: To evaluate the effect of accelerated corneal crosslinking (CXL) with a "higher peripheral intensity" profile setting compared with a standard "top hat" profile setting performed using different CXL systems. SETTING: Department of Ophthalmology, University Hospital Carl Gustav Carus, Dresden, Germany. DESIGN: Retrospective case series. METHODS: Eyes from patients with progressive keratoconus were included. Group 1 included eyes treated with the higher peripheral intensity profile. Group 2 included eyes treated with the top hat profile. Accelerated CXL was performed based on the modified Dresden protocol (9 mW/cm2, 10 minutes). Corneal-topography and tomography are characterized using the Pentacam Scheimpflug system. RESULTS: The study comprised 45 eyes (25 eyes in Group 1, 20 eyes in Group 2) from 45 patients. The keratometry (K) at the apex (maximum K) decreased significantly from 54.95 diopters (D) ± 6.73 (SD) to 53.21 ± 6.05 D for Group 1 (P < .001) and from 57.29 ± 7.16 D to 56.48 ± 6.88 D for Group 2 (P = .01). In Group 1, flat K (K1) and steep K (K2) decreased significantly after treatment (P < .05). The thinnest corneal thickness decreased significantly by -17.5 ± 21.9 µm (P = .001) in Group 1. In Group 2, no significant flattening was observed in K1 and K2 (P > .05), and the thinnest corneal thickness showed a slight but not significant thinning (P = .097). CONCLUSIONS: In Group 1 (the higher peripheral intensity group), the corneal topographic and tomographic parameters improved significantly after accelerated CXL. The higher peripheral intensity profile effect on keratoconic cornea flattening seemed to be more pronounced compared with the top hat profile.

Topical administration of regorafenib eye drops: phase I dose-escalation study in healthy volunteers.

AIM: Regorafenib is a multikinase inhibitor under investigation for use in neovascular age-related macular degeneration. In this phase I study, regorafenib eye drops were administered to healthy volunteers to provide information on safety, tolerability and systemic exposure. METHODS: This was a single-centre, randomized, double-masked, parallel-group, dose-escalation, placebo-controlled study. Subjects received regorafenib eye drops (30 mg ml-1 , 25 µl) as a 0.75 mg single dose (Cohort 1), 0.75 mg twice daily (bid) or thrice daily (tid) over 14 days (Cohorts 2 and 3, respectively), 1.5 mg tid unilaterally for 3 days, then bilaterally for up to 14 days (Cohort 4), or placebo. Plasma samples were taken to estimate systemic exposure. Safety and functional assessments were performed throughout the study. RESULTS: Thirty-six subjects received regorafenib and 12 received placebo. Regorafenib was safe and well tolerated over the dose range. No pathological changes occurred in the anterior, vitreous or posterior eye compartments. Mild eyelid redness, oedema and conjunctival hyperaemia were observed across all regorafenib cohorts; these were comparable with the effects seen with placebo. Predominant symptoms were blurred vision in the active and placebo groups. Systemic safety evaluations showed no clinically relevant findings. Absolute systemic exposure after multiple administrations of regorafenib eye drops at a dose of 0.75 mg was 600-700-fold lower than after multiple oral administration of 160 mg day-1 , the dose approved in cancer indications. CONCLUSION: These results indicate a favourable safety and tolerability profile of regorafenib eye drops up to 30 mg ml-1 tid for use in clinical studies.

[Dacryoendoscopic Surgery-Factors Influencing Postoperative Results]. / Dakryoendoskopische Tränenwegschirurgie ­ Einflussfaktoren auf das postoperative Ergebnis.

BACKGROUND: Dacryoendoscopy (DE) is an established method in lacrimal surgery. Long-term follow-up-analyses of this surgery are of great interest. Here, factors influencing postoperative success rates should be considered to elect suitable patients. METHODS: In this retrospective study, patients having had dacryoendoscopic surgery were included. Using a questionnaire, a prospective follow-up analysis was made. Pre- and intraoperative factors were correlated with treatment success, which was defined as improved epiphora, absence of a second lacrimal surgery and no signs of chronic dacryocystitis (secretion, pain at the lacrimal sac). Additionally, we asked for patient's satisfaction with the postoperative result (categorized in "very good", "good", "poor", and "bad"). RESULTS: Overall, 215 DE of 182 patients (130 women, 52 men) were studied. Mean patient age was 58 ± 17 years (range: 18 to 91 years). Follow-up was 31 to 77 months (median: 55 months). Treatment success after this time was 59.1%, in which neither patient's age nor sex showed significant influences. In comparison to complete stenosis, incomplete obstruction could be treated successfully twice as often (p = 0.02). Patients suffering from ectatic lacrimal sacs had a risk of 1.9 for failing therapy (p = 0.01). A trend concerning worse cure rates could be observed in patients with postsaccal localization of stenosis (p = 0.2) and an age of older than 49 years (p = 0.1). Surgical results evaluated by the patients were "very good" in 32.1% and "good" in 30.2%. CONCLUSION: Dacryoendoscopy with its minimally invasive approach is suitable as a first-step procedure in lacrimal surgery. The absence of a scar and the quick recovery are vitally important for the patients. Medically important is that the topographic anatomy is preserved by using dacryoendoscopy, so other surgical techniques can be performed later without limitations, if necessary. Patients with incomplete obstructions and a localization of stenosis, being pre- to intrasaccal, profit from this treatment method in particular.

Semifluorinated Alkane Eye Drops for Treatment of Dry Eye Disease Due to Meibomian Gland Disease.

PURPOSE: Meibomian gland disease is generally accepted as the leading cause for evaporative dry eye disease (DED). In a previous study, perfluorohexyloctane, a semifluorinated alkane, has been demonstrated to significantly increase tear film breakup time and to reduce corneal fluorescein staining in patients with evaporative DED, thereby vastly reducing dry eye-related symptoms. This study was set up to evaluate perfluorohexyloctane in a larger population of patients with Meibomian gland dysfunction. METHODS: Seventy-two patients with Meibomian gland disease and associated dry eye received 1 drop of perfluorohexyloctane 4 times daily during an observational, prospective, multicenter, 6-8-week study. Clinical assessment included best-corrected visual acuity, intraocular pressure, Schirmer test I, tear film breakup time, anterior and posterior blepharitis assessment, number of expressible Meibomian glands, meibum quality and quantity, ocular surface fluorescein staining, lid margin and symptom assessment, and Ocular Surface Disease Index (OSDI©). RESULTS: From the 72 patients recruited, 61 completed the trial per protocol. Nine patients did not apply the medication as recommended and 2 patients were lost to follow-up. Tear film breakup time, corneal and conjunctival fluorescein staining, number of expressible Meibomian glands, and severity of anterior and posterior blepharitis significantly improved after 6-8 weeks of perfluorohexyloctane application. In addition, symptoms improved as demonstrated by a significant decrease of OSDI-values from 37 (±13) to 26 (±16). CONCLUSIONS: In concordance with previous findings, 6-8 weeks of topical application of perfluorohexyloctane significantly improves clinical signs of Meibomian gland disease and associated mild to moderate DED.

Repeatability and Agreement of Central Corneal Thickness and Keratometry Measurements between Four Different Devices.

Background. To estimate repeatability and comparability of central corneal thickness (CCT) and keratometry measurements obtained by four different devices in healthy eyes. Methods. Fifty-five healthy eyes from 55 volunteers were enrolled in this study. CCT (IOLMaster 700, Pentacam HR, and Cirrus HD-OCT) and keratometry readings (IOLMaster 700, Pentacam HR, and iDesign) were measured. For statistical analysis, the corneal spherocylinder was converted into power vectors (J0, J45). Repeatability was assessed by intraclass correlation coefficient (ICC). Agreement of measurements between the devices was evaluated by the Bland-Altman method. Results. The analysis of repeatability of CCT data of IOLMaster 700, Pentacam HR, and Cirrus HD-OCT showed high ICCs (range 0.995 to 0.999). The comparison of CCT measurements revealed statistically significant differences between Pentacam HR versus IOLMaster 700 (p < 0.0001) and Pentacam HR versus Cirrus HD-OCT (p < 0.0001), respectively. There was no difference in CCT measurements between IOLMaster 700 and Cirrus HD-OCT (p = 0.519). The repeatability of keratometry readings (J0 and J45) of IOLMaster 700, Pentacam HR, and iDesign was also high with ICCs ranging from 0.974 to 0.999. The Pentacam HR revealed significantly higher J0 in comparison to IOLMaster 700 (p = 0.009) and iDesign (p = 0.041); however, no significant difference was between IOLMaster 700 and iDesign (p = 0.426). Comparison of J45 showed no significant difference between IOLMaster 700, Pentacam HR, and iDesign. These results were in accordance with Bland-Altman plots. Conclusion. In clinical practice, the devices analyzed should not be used interchangeably due to low agreement regarding CCT as well as keratometry readings.

Repeatability and agreement in optical biometry of a new swept-source optical coherence tomography-based biometer versus partial coherence interferometry and optical low-coherence reflectometry.

PURPOSE: To estimate the repeatability of biometric parameters obtained with a new swept-source biometer and to compare the agreement with that of partial coherence interferometry (PCI) and optical low-coherence reflectometry (OLCR). SETTING: Department of Ophthalmology, Helios Hospital Erfurt, Erfurt, Julius-Maximilians University, Würzburg, and Philipps University, Marburg, Germany. DESIGN: Prospective comparative multicenter clinical study. METHODS: Biometry was taken with the use of 3 different biometers: the IOLMaster 700 swept-source biometer, the PCI-based IOLMaster 500, and the OCLR-based Lenstar LS 900. Axial length (AL), anterior chamber depth (ACD), and spherical equivalent (SE) were compared between swept-source and PCI biometry and central corneal thickness (CCT) and lens thickness (LT) between swept-source and OLCR biometry. The repeatability of swept-source biometry was evaluated on the basis of 3 measurements captured for each patient. RESULTS: One hundred twenty cataract eyes were included in the study. The mean difference between swept-source and PCI biometry for AL, ACD, and SE measurements was 4 µm ± 25 (SD), 17 ± 122 µm, and -0.001 ± 0.19 diopter (D), respectively. The mean difference between swept-source and OLCR biometry for LT and CCT measurements was 21 ± 122 µm and 0.15 ± 4.51 µm, respectively. Differences between swept-source biometry and the other devices distributed around zero without statistical significance. The standard deviation of repeatability for AL, ACD, LT, CCT, and SE was 8.8 µm, 9.8 µm, 2.3 µm, 19.5 µm, and 0.1 D, respectively. CONCLUSIONS: Swept-source biometry showed high repeatability performance for all biometric parameters. The agreement of AL, ACD, and SE between swept-source and PCI biometry as well as that of LT and CCT between swept-source and OLCR biometry was excellent. It remains to be validated whether high repeatability shown by swept-source biometry will result in better postoperative refractive outcomes. FINANCIAL DISCLOSURE: Drs. Blum and Sekundo are members of the Scientific Advisory Board of Carl Zeiss Meditec AG. Drs. Peter and Bühren are employees of Carl Zeiss Meditec AG.

Five-year results of Small Incision Lenticule Extraction (ReLEx SMILE).

BACKGROUND: To evaluate the 5-year results of Refractive Lenticule Extraction (ReLEx) as Small Incision Lenticule Extraction (SMILE) technique for treatment of myopia and myopic astigmatism. METHODS: In 2008/2009, the worldwide first 91 eyes were treated using a novel surgical technique (SMILE), where a refractive lenticule of intrastromal corneal tissue is removed though a small incision completely eliminating flap-cutting. 56 out of 91 eyes of the original treatment group volunteered for re-examination 5 years after surgery. Uncorrected distance visual acuity and corrected distance visual acuity after 5 years, objective and manifest refractions as well as evaluation of the interface and corneal surface by slit-lamp examination were documented. Late side effects like corneal scars, corneal ectasia, persistent dry eye symptoms or cataract were documented. RESULTS: 5 years postoperatively, no significant change to the 6-month data was found. Spherical equivalent was -0.375 D and therefore close to target refraction (emmetropia). 32 of the 56 eyes had gained 1-2 Snellen lines. There was no loss of 2 or more lines over the 5-year period. Regression in the long term was 0.48 D. CONCLUSIONS: This first long-term study demonstrates SMILE to be an effective, stable and safe procedure for treatment of myopia and myopic astigmatism. CLINICAL TRIAL NUMBER: DE/CA93/KP/07/001. Post-results.

Identifying glaucoma patients by applying multivariate analyses of cardiovascular signals.

Glaucoma is a disease that damages the eye's optic nerve. However, the exact cause of this optic nerve damage is not yet fully understood. Besides the factors of age, genetics and others, such as obesity, medication and migraines, a vascular dysfunction is believed to be a significant factor leading to glaucoma. This study's objective was to investigate whether these vascular dysfunctions could be recognized by analyzing cardiovascular regulation in glaucoma patients. Linear and nonlinear methods were applied to the extracted heart rate (HR), and systolic/ diastolic blood pressure (DBP) time series to discriminate between 35 healthy controls and 20 glaucoma patients. The combination of indices from 30-min analysis of time domain (Renyi entropy of systolic blood pressure) and nonlinear dynamics (segmented Poincare plot analysis of DBP, high-resolution joint symbolic dynamics of DBP/ HR) were able to differentiate between controls and patients with a specificity and sensitivity of > 95%. Since changes in short-term blood pressure regulation patterns and heart-rate coupling are clear signs of a vascular dysfunction, this approach could be useful for providing an earlier diagnosis of glaucoma in clinical practice.

Topographic Findings of the Porcine Cornea.

The porcine eye is often used as an ex vivo animal model in ophthalmological research. It is well suited for investigations concerning refractive surgery; however, corneal topography data are scarce. This study investigated the corneal topography and pachymetry of the porcine eye to provide further reproducible data. We evaluated freshly enucleated porcine eyes (n = 16) by performing computerized corneal topographies (Orbscan® IIz, Bausch and Lomb, Rochester, NY, USA). We assessed the steepest and flattest keratometric powers (K1 and K2, units in diopters (D)), astigmatism (D), white-to-white (WTW) diameter (mm), thinnest point pachymetry (µm), anterior and posterior best-fit sphere (BFS) (D), refractive power of the anterior and posterior curvatures, and total refractive power of the cornea (D). The mean keratometric powers were 39.6 ± 0.89 D (K1) and 38.5 ± 0.92 D (K2), and the mean astigmatism was 1.1 ± 0.78 D. The mean WTW diameter was 13.81 ± 0.83 mm, and the mean corneal thickness was 832.6 ± 40.18 µm. The BFSs were 38.14 ± 0.73 D (anterior) and 42.56 ± 1.15 D (posterior), and the mean refractive powers were 43.27 ± 1.08 D (anterior) and -5.15 ± 0.20 D (posterior); therefore, the mean of the total refractive power was 38.16 ± 1.00 D. The topography and pachymetry of the porcine cornea showed a specific configuration differing from the human cornea. When using animal ex vivo models such as porcine corneas for experimental corneal surgery, findings such as these should be considered.

Foveal pit morphology evaluation during optical biometry measurements using a full-eye-length swept-source OCT scan biometer prototype.

PURPOSE: To assess the scan quality of foveal pit morphology (FPM) and to quantify central retinal thickness (CRT) during routine optical biometry measurements with a full-eye-length swept-source optical coherence tomography (SS-OCT) scan biometer prototype (IOLMaster700) and to compare these results with standard examinations using spectral-domain optical coherence tomography (SD-OCT) technique (Cirrus4000 SD-OCT). METHODS: As part of a SS-OCT scan protocol to measure biometric parameters for intraocular lens power calculation, central horizontal 1 mm retinal B scans were taken from phakic (group I) and pseudophakic (group II) nonvitrectomized eyes. To evaluate FPM, macular scans of either examination technique were subjectively analyzed and compared. Repeated CRT measurements were performed to analyze repeatability and consistency of IOLMaster700 recordings. These results were compared with CRT evaluations using SD-OCT. RESULTS: Overall, 146 eyes of 146 patients were included in this series. The subjective assessments of FPM are illustrated. Repeated CRT measurements (repeatability) with the IOLMaster700 disclosed an overall intraclass correlation of 0.57 (group I: 0.48; group II: 0.89). Overall coefficient of variation (accuracy) was calculated to be 12.43% (group I: 14.21%; group II: 5.66%). The comparison of CRT measurements between both devices showed significant differences in group I (p = 0.006). CONCLUSIONS: Compared with SD-OCT, resolution of the 1 mm retinal B scan of SS-OCT scan biometry was lower. However, advanced pathologic characteristics were clearly discernible. Repeatability and accuracy of CRT measurements were acceptable though lower than with the standard SD-OCT technique. The CRT differed significantly in eyes of particular interest (group I) between both devices. The new scan could provide useful information for subsequent patient examination and further treatment planning for cataract surgery.

Five-year results of refractive lenticule extraction.

PURPOSE: To evaluate the 5-year results of femtosecond laser-assisted refractive lenticule extraction (ReLEx-FLEx) for the treatment of myopia and myopic astigmatism. SETTING: Departments of Ophthalmology, Helios Klinikum Erfurt, Erfurt, and Phillips Universität Marburg, Marburg, Germany. DESIGN: Prospective clinical trial. METHODS: This was a follow-up of a prospective study that evaluated the first patients treated with refractive lenticule extraction, in which a flap and a refractive lenticule of intrastromal corneal tissue were simultaneously cut using a 200 kHz Visumax femtosecond laser system. Thereafter, the lenticule was manually removed and the flap repositioned. The main outcome measures were the uncorrected and corrected distance visual acuities, objective and manifest refractions, slitlamp examination findings, and side effects after 5 years. RESULTS: Forty-one of 108 eyes in the original treatment group were available for a reexamination. Five years postoperatively, 100% of eyes were within ±1.00 diopter (D) of the intended correction and 73% were within ±0.50 D. By 5 years, no eye had lost 2 or more Snellen lines and 1 eye had lost 1 Snellen line. The mean regression was 0.07 D. CONCLUSION: Long-term data indicate that refractive lenticule extraction is an effective and safe procedure for the treatment of myopia and myopic astigmatism and has excellent stability. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Influence of microkeratome parameters on the stromal bed and flap edge quality in laser in situ keratomileusis.

PURPOSE: Femtosecond lasers have become the standard for laser-assisted in situ keratomileusis (LASIK) flap creation, but advanced mechanical microkeratomes are still an alternative, more cost-effective way to create the flap. The SCHWIND Carriazo-Pendular microkeratome is one of the most commonly used microkeratomes. The influence of different cutting parameters (head-advance speeds, cutting heads) on morphology of LASIK cuts was investigated. SETTING: Experimental study performed at the University Eye Hospital of the Martin Luther University Halle/Wittenberg, Halle (Saale), Germany. METHODS: The Carriazo-Pendular microkeratome was used on freshly enucleated porcine eyes for lamellar keratotomy. After flap removal, the cutting edge and stromal bed were evaluated from scanning electron micrographs using an individualized scoring system. Four different settings of microkeratome parameters were compared. For each setting, eight cuts were evaluated (n=32). RESULTS: Different oscillation frequencies and head-advance speeds did not influence the cutting qualities. A higher oscillation/feed rate ratio seemed to be advantageous for a smoother interface. Concerning different cuttings heads, a deeper keratotomy led to sharper cutting edges. The thinner the flap, the more irregularities in the stromal bed appeared. Complications did not occur. CONCLUSION: The Carriazo-Pendular microkeratome is a safe tool with which to create a LASIK flap and is a good alternative to a costly femtosecond laser. Deeper keratotomies, as well as the use of a higher oscillation/feed rate quotient, improve the cutting quality.