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Tromsø, Norway

Chen S.,Wenzhou Medical College | Feng Y.,Wenzhou Medical College | Stojanovic A.,University of Tromso | 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.

Lagali N.,Linkoping University | Eden U.,Linkoping 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.

Hua Y.,Shanghai JiaoTong University | Stojanovic A.,University of Tromso | Stojanovic A.,SynsLaser Kirurgi AS | Utheim T.P.,University of Oslo | And 4 more authors.
PLoS ONE | Year: 2015

Purpose: To determine the keratometric indices calculated based on parameters obtained by Fourier-domain optical coherence tomography (FD-OCT). Methods: 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. Results: 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. Conclusion: 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. © 2015 Hua et al.

Stojanovic A.,SynsLaser Kirurgi AS | Stojanovic A.,University of Tromso | 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 | Chen X.,SynsLaser Kirurgi AS | Stojanovic A.,SynsLaser Kirurgi | Stojanovic A.,SynsLaser Kirurgi AS | And 9 more authors.
Journal of Refractive Surgery | Year: 2012

PURPOSE: To evaluate the residual registration error after limbal-marking-based manual adjustment in cyclotorsional tracker-controlled laser refractive surgery. METHODS: Two hundred eyes undergoing custom surface ablation with the iVIS Suite (iVIS Technologies) were divided into limbal marked (marked) and non-limbal marked (unmarked) groups. Iris registration information was acquired preoperatively from all eyes. Preoperatively, the horizontal axis was recorded in the marked group for use in manual cyclotorsional alignment prior to surgical iris registration. During iris registration, the preoperative iris information was compared to the eye-tracker captured image. The magnitudes of the registration error angle and cyclotorsional movement during the subsequent laser ablation were recorded and analyzed. RESULTS: Mean magnitude of registration error angle (absolute value) was 1.82°±1.31° (range: 0.00° to 5.50°) and 2.90°±2.40° (range: 0.00° to 13.50°) for the marked and unmarked groups, respectively (P<.001). Mean magnitude of cyclotorsional movement during the laser ablation (absolute value) was 1.15°±1.34°(range: 0.00° to 7.00°) and 0.68°±0.97° (range: 0.00°to 6.00°) for the marked and unmarked groups, respectively (P=.005). Forty-six percent and 60% of eyes had registration error >2°, whereas 22% and 20% of eyes had cyclotorsional movement during ablation >2° in the marked and unmarked groups, respectively. CONCLUSIONS: Limbal-marking-based manual alignment prior to laser ablation significantly reduced cyclotorsional registration error. However, residual registration misalignment and cyclotorsional movements remained during ablation. Copyright © SLACK Incorporated.

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