The ultrastructure of rabbit sclera after scleral crosslinking with riboflavin and blue light of different intensities.

Purpose: We aimed to determine the ultrastructural changes of collagen fibrils and cells in the rabbit sclera after scleral crosslinking using riboflavin and blue light of different intensities. Scleral crosslinking is known to increase scleral stiffness and may inhibit the axial elongation of progressive myopic eyes.

Methods: The equatorial parts of the sclera of one eye of six adult albino rabbits were treated with topical riboflavin solution (0.

Scleral cross-linking by riboflavin and blue light application in young rabbits: damage threshold and eye growth inhibition.

Background: Scleral cross-linking (SXL) by riboflavin and light application has been introduced as a possible treatment to increase scleral tissue stiffness and to inhibit excessive axial elongation of highly myopic eyes. We evaluated an ocular tissue damage threshold for blue light irradiation, and used SXL treatment to induce eye growth inhibition.

Methods: The sclera of 3-week-old rabbits (39 pigmented and 15 albino rabbits) were treated with different blue light intensities (450 ± 50 nm) and riboflavin.

Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application.

Several scleral cross-linking (SXL) methods were suggested to increase the biomechanical stiffness of scleral tissue and therefore, to inhibit axial eye elongation in progressive myopia. In addition to scleral cross-linking and biomechanical effects caused by riboflavin and light irradiation such a treatment might induce tissue damage, dependent on the light intensity used. Therefore, we characterized the damage threshold and mechanical stiffening effect in rabbit eyes after application of riboflavin combined with various blue light intensities.

Dose-dependent collagen cross-linking of rabbit scleral tissue by blue light and riboflavin treatment probed by dynamic shear rheology.

Purpose: To determine the visco-elastic properties of isolated rabbit scleral tissue and dose-dependent biomechanical and morphological changes after collagen cross-linking by riboflavin/blue light treatment.

Material: Scleral patches from 87 adult albino rabbit eyes were examined by dynamic shear rheology. Scleral patches were treated by riboflavin and different intensities of blue light (450 nm), and the impact on the visco-elastic properties was determined by various rheological test regimes.

Laboratory measurement of the absorption coefficient of riboflavin for ultraviolet light (365 nm).

Purpose: Corneal cross-linking (CXL) is an increasingly used treatment technique for stabilizing the cornea in keratoconus. Cross-linking (polymerization) between collagen fibrils is induced by riboflavin (vitamin B2) and ultraviolet light (365 nm). Although reported to reach a constant value at higher riboflavin concentrations, the Lambert-Beer law predicts a linear increase in the absorption coefficient.

Scheimpflug imaging of corneas after collagen cross-linking.

Purpose: To compare geometrical shape factors of keratoconus corneas after cross-linking (CXL) by means of Scheimpflug imaging with those of untreated fellow eyes.

Setting: Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland.

Methods: Scheimpflug imaging of the anterior segments was performed with the Pentacam (Oculus, Wetzlar, Germany) in 21 patients with progressive keratectasia before and after CXL.

Collagen crosslinking with ultraviolet-A and hypoosmolar riboflavin solution in thin corneas.

Corneal collagen crosslinking (CXL) with riboflavin and ultraviolet-A light is a method for treating progressive keratectasia. The currently accepted treatment parameters induce collagen crosslinking in the anterior 250 to 350 microm of corneal stroma. To protect the endothelium, CXL inclusion criteria require a minimum corneal thickness of 400 microm after removal of the epithelium.

Efficacy and safety of blue-light scleral cross-linking.

Purpose: To evaluate the efficacy of blue-light scleral cross-linking as well as its safety in preventing retinal damage beneath the treated sclera.

Methods: Six rabbits were unilaterally treated with topical riboflavin (0.5%) and blue light (465 nm) on the equatorial sclera using a light emitting diode source with an exposure area of 9 mm in diameter.

Pregnancy-related exacerbation of iatrogenic keratectasia despite corneal collagen crosslinking.

Iatrogenic keratectasia after laser in situ keratomileusis (LASIK) represents a serious complication of refractive laser surgery. We describe a woman who developed bilateral iatrogenic keratectasia during her first pregnancy 26 months after LASIK. Corneal collagen crosslinking (CCL) with riboflavin and ultraviolet-A was performed in March 2005 (right eye) and April 2005 (left eye).

Ultraviolet A/riboflavin corneal cross-linking for infectious keratitis associated with corneal melts.

Purpose: To evaluate the efficacy of ultraviolet-corneal cross-linking (CXL) for treating infectious melting keratitis.

Methods: Five patients with infectious keratitis associated with corneal melting were treated with CXL at the outpatient departments of the Institut für Refraktive und Ophthalmo-Chirurgie and the eye hospital at the University of Zurich. CXL was performed when the infection did not respond to systemic and topical antibiotic therapy.

Topography-guided surface ablation for forme fruste keratoconus.

Purpose: To evaluate the efficacy of customized surface ablation in cases of forme fruste keratoconus.

Design: Prospective noncomparative case series.

Participants: Eleven eyes of 8 contact lens-intolerant patients with forme fruste keratoconus treated at the Institute of Refractive and Ophthalmic Surgery and the University Eye Clinic Zurich.

Corneal and total wavefront aberrations in phakic and pseudophakic eyes after implantation of monofocal foldable intraocular lenses.

Purpose: To compare the correlation between corneal and total wavefront aberrations in normal phakic and pseudophakic eyes after implantation of foldable monofocal intraocular lenses (IOLs).

Setting: University Hospital, Eye Clinic, Zurich, Switzerland.

Methods: Wavefront aberrations and corneal topography of 29 eyes that had cataract surgery with implantation of hydrophobic monofocal foldable IOL (AcrySof, Alcon Labs) were measured at least 2 months postoperatively and compared with wavefront measurements performed in 33 normal young phakic eyes.

The effect of phenylephrine and cyclopentolate on objective wavefront measurements.

Purpose: To investigate the impact of phenylephrine and cyclopentolate on wavefront refraction and fourth order spherical aberration C12.

Methods: This cohort study comprised 151 eyes with sphere up to -10.00 diopters (D) and cylinder -3.

Q-factor customized ablation profile for the correction of myopic astigmatism.

Purpose: To compare the results of the Q-factor customized aspheric ablation profile with the wavefront-guided customized ablation pattern for the correction of myopic astigmatism.

Setting: Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland.

Methods: Thirty-five patients were enrolled in a controlled study in which the nondominant eye was treated with the Q-factor customized profile (custom-Q study group) and the dominant eye was treated with wavefront-guided customized ablation (control group).

Treatment-induced shifts of ocular reference axes used for measurement centration.

Purpose: To determine the shifts of the main corneal reference points in dependence of the chosen centration axis for the treatment.

Setting: Federal Institute of Technology Zurich, Institute of Biomedical Engineering, Zurich, Switzerland.

Methods: Computer simulations were performed on several variants of the Gullstrand-Emsley schematic eye, which was modified by an off-axis fovea.

Clinical photoablation with a 500-Hz scanning spot excimer laser.

Purpose: The aim of this study was to use a 500-Hz scanning spot laser (Concept500, WaveLight Laser Technologie AG, Erlangen, Germany) to investigate potential side effects that might be associated with the use of a high repetition rate laser platform.

Methods: Seven eyes were treated using a 500-Hz scanning spot laser for laser in situ keratomileusis (LASIK). The local frequency of the ablation was kept below 40 Hz to avoid local heating of corneal tissue.

Transferring wavefront measurements into corneal ablations: an overview of related topics.

We give an overview of possible side effects that are specific for, or of particular relevance in, customized treatments. Certain processes involved in customized ablations have the potential to alter the quality of the optical correction. Professionals associated with customized treatment should be informed and trained with respect to possible sources of error.

Conservative treatment of vertical diplopia in a patient with silent sinus syndrome.

Silent sinus syndrome is a rare disease of the maxillary sinus characterized by bony absorption processes leading to progressive sinus wall thinning with consecutive enophthalmos and hypoglobus. It represents a benign cause of acquired enophthalmos and is often accompanied by painless vertical diplopia, the latter treated surgically in all cases published to date. We report a 56-year-old patient with silent sinus syndrome in whom vertical diplopia was treated with prisms showing that conservative treatment alone may, in mild cases, be an effective alternative to reconstructive surgery.

Light damage susceptibility and RPE65 in rats.

A sequence variation in the pigment epithelial protein RPE65 has been shown to correlate with RPE65 protein levels, rhodopsin regeneration kinetics and light damage susceptibility in different mouse strains. Here, we tested whether such a correlation can also be found in rats. We examined four rat strains for RPE65 protein levels and the Rpe65 gene sequence.

Fra-1 substitutes for c-Fos in AP-1-mediated signal transduction in retinal apoptosis.

Lack of the AP-1 member c-Fos protects photoreceptors against light-induced apoptosis, a model for retinal degeneration. In mice, light damage increases the activity of the transcription factor AP-1, while pharmacological suppression of AP-1 prevents apoptosis, suggesting the involvement of pro-apoptotic AP-1 target genes. Recently, however, it was shown that photoreceptors expressing Fra-1 in place of c-Fos (Fos (Fosl1/Fosl1) ) are apoptosis competent despite the lack of transactivation domains in Fra-1.