SynsLaser Kirurgi AS

Tromsø, Norway

SynsLaser Kirurgi AS

Tromsø, Norway

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Stojanovic A.,SynsLaser Kirurgi AS | Stojanovic A.,University of Tromsø | Zhou W.,SynsLaser Kirurgi AS | Utheim T.P.,University of Oslo
BioMed Research International | Year: 2014

Purpose. Our main purpose was to compare safety and efficacy in the treatment of progressive keratoconus with "epithelium-on" and "epithelium-off" corneal collagen cross-linking (CXL). Our secondary purpose was to evaluate efficacy of CXL when hypotonic 0.5% riboflavin is used as photosensitizer. Methods. One eye of 20 patients with bilateral progressive keratoconus was randomly treated for "epithelium-on" CXL (group 1) while the fellow eye underwent "epithelium-off" CXL (group 2). Hypotonic 0.5% riboflavin was used in both groups. Visual acuity, refraction, corneal topography, and wavefront aberrometry were evaluated at baseline and after 1, 6, and 12 months. Specular microscopy was performed on 10 patients preoperatively and after 12 months. Postoperative pain was evaluated using a patient questionnaire. Results. Uncorrected and corrected distance visual acuity improved significantly in both groups. Refraction, topography, and aberrometry showed nonsignificant changes from the preoperative status throughout the 12-month follow-up in both groups. Moreover, the outcomes between the groups were comparable at all follow-up points. Endothelial cell-count was stable. Postoperative pain length was shorter in group 1 P < 0.001. Conclusion. "Epithelium-on" and "epithelium-off" CXL using hypotonic 0.5% riboflavin were equally safe and effective in stabilization of keratoconus. Topography and aberrometry outcomes in both groups failed to show any significant improvements. This study is registered at ClinicalTrials.gov: NCT01181219. © 2014 Aleksandar Stojanovic et al.


Chen X.,SynsLaser Kirurgi AS | Chen X.,University of Oslo | Chen X.,University of Tromsø | Stojanovic A.,SynsLaser Kirurgi AS | And 5 more authors.
Journal of Refractive Surgery | Year: 2015

PURPOSE: To study the corneal epithelial and stromal thickness profile changes after photorefractive keratectomy (PRK) for myopia. METHODS: Retrospective analysis of the postoperative corneal epithelial and stromal thickness profile changes in 46 left eyes of 46 patients treated with PRK for myopia. Corneal and epithelial thickness maps within the central 6 mm were obtained by anterior segment spectral-domain optical coherence tomography preoperatively and at 1, 3, and 6 months postoperatively. Stromal thickness was calculated by subtracting the epithelial thickness from the total corneal thickness. Correlations between postoperative thickness changes and the amount of correction, treatment zone, and preoperative epithelial thickness were analyzed. RESULTS: Compared to preoperative values, the central 2 mm and the paracentral 2- to 5-mm zone epithelium was 5.20 ± 3.43 and 5.72 ± 3.30 μm thicker, respectively, at 3 months postoperatively (P < .05). No significant difference was detected between 3 and 6 months postoperatively. The stromal thickness did not change between 1 and 6 months postoperatively. The spherical equivalent (SE) changed from -2.82 ± 1.54 diopters (D) preoperatively to -0.06 ± 0.42 D at 1 month postoperatively, and remained stable thereafter. There was a trend toward greater epithelial thickening with a larger amount of programmed SE correction, smaller treatment zone, and thinner preoperative epithelium. No correlation between epithelial thickness change and postoperative change in refraction was detected. CONCLUSIONS: The corneal epithelial thickness increased after PRK up to 3 months postoperatively. It was affected by the amount of myopia treated, treatment zone, and preoperative epithelial thickness. The postoperative epithelial thickening did not affect the refractive outcomes. © SLACK Incorporated.


Chen X.,SynsLaser Kirurgi AS | Stojanovic A.,SynsLaser Kirurgi AS | Stojanovic A.,University of Tromsø | Stojanovic A.,University of Oslo | And 4 more authors.
Journal of Refractive Surgery | Year: 2012

PURPOSE: To evaluate the efficacy and safety of a single-step, transepithelial, topography-guided surface ablation in the treatment of visual disturbances including irregular astigmatism and light scattering caused by LASIK flap or interface complications. METHODS: Seventeen eyes of 16 patients with LASIK flap or interface complications and central residual stromal thickness ≥300 μm were treated with a topography- guided custom transepithelial "no touch" (cTEN) technique using the iVIS Suite 1-kHz excimer laser (iVIS Technology). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, corneal irregularity, ocular higher order aberrations (HOAs), and visual symptoms were analyzed. RESULTS: Mean 15.9±11.0 months after surgery, mean UDVA improved from 20/87 to 20/25. Mean CDVA improved from 20/28 to 20/19 (P<.001), with 64.7% of eyes gaining two or more lines of CDVA. Mean corneal irregularity index decreased from 25.82 to 20.36 μm (P=.009). Mean root-mean-square (RMS) of total HOAs decreased from 1.30 to 0.49 (P=.042), whereas RMS of the odd-order (3rd and 5th) and evenorder (4th and 6th) HOAs decreased from 0.85 to 0.38 (P=.001) and 0.43 to 0.24 (P=.036), respectively. All patients claimed their visual symptoms were better (8 eyes) or cured (9 eyes). CONCLUSIONS: Corneal regularization and removal of the underlying flap or interface pathology by cTEN ablation appears to be an effective treatment for LASIK flap or interface complications associated with visually disturbing irregular astigmatism and light scattering in cases with sufficient residual stromal thickness. Copyright © SLACK Incorporated.


Lagali N.,Linköping University | Eden U.,Linköping University | Utheim T.P.,University of Oslo | Utheim T.P.,Massachusetts Eye and Ear Infirmary | And 4 more authors.
Investigative Ophthalmology and Visual Science | Year: 2013

PURPOSE. To investigate morphologic alterations in the limbal palisades of Vogt in a progressive form of limbal stem cell deficiency. METHODS. Twenty Norwegian subjects (40 eyes) with congenital aniridia and 9 healthy family members (18 eyes) without aniridia were examined. Clinical grade of aniridia-related keratopathy (ARK) was assessed by slit-lamp biomicroscopy, and tear production and quality, corneal thickness, and sensitivity were additionally measured. The superior and inferior limbal palisades of Vogt and central cornea were examined by laser scanning in vivo confocal microscopy (IVCM). RESULTS. In an aniridia patient with grade 0 ARK, a transparent cornea and normal limbal palisade morphology were found. In grade 1 ARK, 5 of 12 eyes had degraded palisade structures. In the remaining grade 1 eyes and in all 20 eyes with stage 2, 3, and 4 ARK, palisade structures were absent by IVCM. Increasing ARK grade significantly correlated with reduced visual acuity and corneal sensitivity, increased corneal thickness, degree of degradation of superior and inferior palisade structures, reduced peripheral nerves, increased inflammatory cell invasion, and reduced density of basal epithelial cells and central subbasal nerves. Moreover, limbal basal epithelial cell density and central corneal subbasal nerve density were both significantly reduced in aniridia compared to healthy corneas (P=0.002 and 0.003, respectively). CONCLUSIONS. Progression of limbal stem cell deficiency in aniridia correlates with degradation of palisade structures, gradual transformation of epithelial phenotype, onset of inflammation, and a corneal nerve deficit. IVCM can be useful in monitoring early- to late-stage degenerative changes in stem cell-deficient patients. © 2013 The Association for Research in Vision and Ophthalmology, Inc.


PubMed | University of Tromsø, SynsLaser Kirurgi AS, Shanghai JiaoTong University, Wenzhou University and University of Oslo
Type: Journal Article | Journal: PloS one | Year: 2015

To determine the keratometric indices calculated based on parameters obtained by Fourier-domain optical coherence tomography (FD-OCT).The ratio of anterior corneal curvature to posterior corneal curvature (Ratio) and keratometric index (N) were calculated within central 3 mm zone with the RTVue FD-OCT (RTVue, Optovue, Inc.) in 186 untreated eyes, 60 post-LASIK/PRK eyes, and 39 keratoconus eyes. The total corneal powers were calculated using different keratometric indices: Kcal based on the mean calculated keratometric index, K1.3315 calculated by the keratometric index of 1.3315, and K1.3375 calculated by the keratometric index of 1.3375. In addition, the total corneal powers based on Gaussian optics formula (Kactual) were calculated.The means for Ratio in untreated controls, post-LASIK/PRK group and keratoconus group were 1.176 0.022 (95% confidence interval (CI), 1.172-1.179), 1.314 0.042 (95%CI, 1.303-1.325) and 1.229 0.118 (95%CI, 1.191-1.267), respectively. And the mean calculated keratometric index in untreated controls, post-LASIK/PRK group and keratoconus group were 1.3299 0.00085 (95%CI, 1.3272-1.3308), 1.3242 0.00171 (95%CI, 1.3238-1.3246) and 1.3277 0.0046 (95%CI, 1.3263-1.3292), respectively. All the parameters were normally distributed. The differences between Kcal and Kactual, K1.3315 and Kactual, and K1.3375 and Kactual were 0.00 0.11 D, 0.21 0.11 D and 0.99 0.12 D, respectively, in untreated controls; -0.01 0.20 D, 0.85 0.18 D and 1.56 0.16 D, respectively, in post-LASIK/PRK group; and 0.03 0.67 D, 0.56 0.70 D and 1.40 0.76 D, respectively, in keratoconus group.The calculated keratometric index is negatively related to the ratio of anterior corneal curvature to posterior corneal curvature in untreated, post-LASIK/PRK, and keratoconus eyes, respectively. Using the calculated keratometric index may improve the prediction accuracies of total corneal powers in untreated controls, but not in post-LASIK/PRK and keratoconus eyes.


Chen S.,Wenzhou Medical College | Feng Y.,Wenzhou Medical College | Stojanovic A.,University of Tromsø | Stojanovic A.,SynsLaser Kirurgi AS | And 2 more authors.
Journal of Refractive Surgery | Year: 2012

PURPOSE: To evaluate the safety, efficacy, and predictability of IntraLase (Abbott Medical Optics) femtosecond laser-assisted compared to microkeratome-assisted myopic LASIK. METHODS: A comprehensive literature search of Cochrane Library, PubMed, and EMBASE was conducted to identify relevant trials comparing LASIK with IntraLase femtosecond laser to LASIK with microkeratomes for the correction of myopia. Meta-analyses were performed on the primary outcomes (loss of ≥2 lines of corrected distance visual acuity [CDVA], uncorrected distance visual acuity [UDVA] 20/20 or better, manifest refraction spherical equivalent [MRSE] within ±0.50 diopters [D], final refractive SE, and astigmatism), and secondary outcomes (flap thickness predictability, changes in higher order aberrations [HOAs], and complications). RESULTS: Fifteen articles describing a total of 3679 eyes were identified. No significant differences were identified between the two groups in regards to a loss of ≥2 lines of CDVA (P=.44), patients achieving UDVA 20/20 or better (P=.24), final UDVA (P=.12), final mean refractive SE (P=.74), final astigmatism (P=.27), or changes in HOAs. The IntraLase group had more patients who were within ±0.50 D of target refraction (P=.05) compared to the microkeratome group, and flap thickness was more predictable in the IntraLase group (P<.0001). The microkeratome group had more epithelial defects (P=.04), whereas the IntraLase group had more cases of diffuse lamellar keratitis (P=.01). CONCLUSIONS: According to the available data, LASIK with the IntraLase femtosecond laser offers no significant benefits over LASIK with microkeratomes in regards to safety and efficacy, but has potential advantages in predictability. Copyright © SLACK Incorporated.


Chen X.,SynsLaser Kirurgi AS | Stojanovic A.,SynsLaser Kirurgi AS | Stojanovic A.,University of Tromsø | Nitter T.A.,Oyelegesenteret
Journal of Refractive Surgery | Year: 2010

PURPOSE: To describe a new, single-step, transepithelial and trans-LASIK flap topography-guided surface ablation technique in a case of recurrent epithelial ingrowth with visual disturbances caused by irregular astigmatism, scattering, and decreased corneal transparency after LASIK. METHODS: Custom ablation through both the epithelium and the LASIK flap performed by 1-kHz flying spot excimer laser was used to transform an irregular corneal surface into a regular aspheric surface and in the same continuous process to ablate the epithelial ingrowth causing the irregularity. RESULTS: Visual rehabilitation was achieved, the corneal surface was regularized, and epithelial ingrowth was removed within the ablation. CONCLUSIONS: The transepithelial topography-guided surface ablation technique was safe and effective in this case of visually disturbing epithelial ingrowth after LASIK, and may also be applied to treat other types of flap/interface complications. Copyright © SLACK Incorporated.


Zhou W.,SynsLaser Kirurgi AS | Stojanovic A.,SynsLaser Kirurgi AS | Stojanovic A.,University of Tromsø
PLoS ONE | Year: 2014

Purpose: To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain optical coherence tomography (SD-OCT). Patients and Methods: We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1) and in 20 healthy subjects with corneal astigmatism ≥2 D (group 2). Epithelial and stromal thicknesses were measured at 11 strategic locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry superimposition was used in the statistical analysis. Results: The mean maximum keratometry measurements in groups 1 and 2 were 47.9±2.9 D (range, 41.8-52.8) and 45.6±1.1 D (range, 42.3-47.5), respectively, with mean corneal cylinders of 3.3±2.2 D (range, 0.5-9.5) and 3.6±1.2 D (range, 2.0-6.4), respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.4±4.4 μm) at 1.2 mm inferotemporally and the highest (59.3±4.4 mm) at 1.4 mm supranasally from the corneal vertex. There was only a small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups. The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally lower in group 1 than in group 2. Conclusions: SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of keratoconus. Trial Registration: ClinicalTrials.gov NCT02023619 © 2014 Zhou, Stojanovic.


PubMed | University of Tromsø and SynsLaser Kirurgi AS
Type: Journal Article | Journal: PloS one | Year: 2014

To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain optical coherence tomography (SD-OCT).We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1) and in 20 healthy subjects with corneal astigmatism 2 D (group 2). Epithelial and stromal thicknesses were measured at 11 strategic locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry superimposition was used in the statistical analysis.The mean maximum keratometry measurements in groups 1 and 2 were 47.9 2.9 D (range, 41.8-52.8) and 45.6 1.1 D (range, 42.3-47.5), respectively, with mean corneal cylinders of 3.3 2.2 D (range, 0.5-9.5) and 3.6 1.2 D (range, 2.0-6.4), respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.4 4.4 m) at 1.2 mm inferotemporally and the highest (59.3 4.4 m) at 1.4 mm supranasally from the corneal vertex. There was only a small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups. The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally lower in group 1 than in group 2.SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of keratoconus.ClinicalTrials.gov NCT02023619.


Chen S.-H.,Wenzhou Medical College | Feng Y.-F.,Wenzhou Medical College | Stojanovic A.,SynsLaser Kirurgi AS | Wang Q.-M.,Wenzhou Medical College
Journal of Refractive Surgery | Year: 2011

PURPOSE: To evaluate the current clinical evidence of safety and efficacy of intraoperative topical application of 0.02% mitomycin C (MMC) used for up to 2 minutes after surface ablation for correction of myopia. METHODS: A comprehensive literature search was conducted of Cochrane Library, MEDLINE, and EMBASE to identify relevant trials comparing surface ablation for correction of myopia with and without MMC. A meta-analysis was performed on the results of the reports and statistical analysis was performed. RESULTS: Eleven clinical trials were identified with MMC used in 534 eyes and no MMC in 726 eyes. Surface ablations with MMC led to significantly less corneal haze in photorefractive keratectomy, whereas the results were comparable in laser epithelial keratomileusis (LASEK) and epithelial laser in situ keratomileusis (epi-LASIK). Although proportionately more eyes in the MMC group achieved uncorrected distance visual acuity 20/25 or better and less frequently lost ≥2 lines of corrected distance visual acuity, the difference was not statistically significant. CONCLUSIONS: Our meta-analysis suggests that the topical intraoperative application of 0.02% MMC may reduce haze and improve visual acuity after surface ablation for correction of myopia. However, the advantage of using MMC in LASEK and epi-LASIK is unclear. Copyright © SLACK Incorporated.

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