Acute corneal melt and perforation - A possible complication after riboflavin/UV-A crosslinking (CXL) in keratoconus.

Purpose: To report two cases of acute corneal melting and perforation requiring emergency penetrating keratoplasty after corneal crosslinking (CXL) in advanced keratoconus.

Observations: Case 1 was a 34 and case 2 was a 16-year old male, both with progressive keratoconus, who underwent CXL (Dresden protocol). After riboflavin imbibition, patients had a minimal pachymetry of 337 μm and 347 μm, and therefore required stromal swelling by hypoosmolar riboflavin resulting in pachymetries of 470 μm and 422 μm, prior to the 30 minute UV-irradiation with 3mW/cm.

Tuck-and-pull technique for posterior chamber phakic intraocular lens explantation.

The tuck-and-pull technique was developed for practical and safe explantations of posterior chamber phakic intraocular lenses (PCPIOLs). In this technique, after the creation of a side port, viscoelastic (or OVD [ophthalmic viscosurgical device]) is initially injected behind the PCPIOL to widen the space between PCPIOL and the crystalline lens. The old incisions can be used after recent implantations rendering the enlargement of the main incision unnecessary.

Selective Equatorial Sclera Crosslinking in the Orbit Using a Metal-Coated Polymer Waveguide.

Purpose: Photochemical crosslinking of the sclera is an emerging technique that may prevent excessive eye elongation in pathologic myopia by stiffening the scleral tissue. To overcome the challenge of uniform light delivery in an anatomically restricted space, we previously introduced the use of flexible polymer waveguides. We presently demonstrate advanced waveguides that are optimized to deliver light selectively to equatorial sclera in the intact orbit.

Spatially-resolved Brillouin spectroscopy reveals biomechanical abnormalities in mild to advanced keratoconus in vivo.

Mounting evidence connects the biomechanical properties of tissues to the development of eye diseases such as keratoconus, a disease in which the cornea thins and bulges into a conical shape. However, measuring biomechanical changes in vivo with sufficient sensitivity for disease detection has proven challenging. Here, we demonstrate the diagnostic potential of Brillouin light-scattering microscopy, a modality that measures longitudinal mechanical modulus in tissues with high measurement sensitivity and spatial resolution.

Intraoperative Optical Coherence Tomography-Guided Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty.

Purpose: To describe the feasibility and outcomes of intraoperative optical coherence tomography (OCT)-guided, femtosecond laser-assisted deep anterior lamellar keratoplasty in which the lamellar and tunnel cuts were completed by laser.

Methods: The Ziemer Z8 system was used to scan the corneas intraoperatively and guide the stromal lamellar and tunnel cuts created by the laser. Thirty porcine eyes and 3 human cadaver globes were used to evaluate the accuracy of laser-created intrastromal tunnels and the feasibility of achieving big-bubble pneumatic dissection.

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.

Wound healing in rabbit corneas after flapless refractive lenticule extraction with a 345 nm ultraviolet femtosecond laser.

Purpose: To characterize corneal wound healing in a rabbit model after flapless refractive lenticule extraction with a 345 nm ultraviolet femtosecond laser.

Setting: Departments of Ophthalmology and Anatomy II, University of Erlangen-Nürnberg and Wavelight GmbH, Erlangen, Germany.

Design: Experimental study.

Flexible Optical Waveguides for Uniform Periscleral Cross-Linking.

Purpose: Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery.

PAX6 Expression and Retinal Cell Death in a Transgenic Mouse Model for Acute Angle-Closure Glaucoma.

Purpose: PAX6 is a highly conserved protein essential for the control of eye development both in invertebrates and vertebrates. PAX6 expression persists in the adult inner retina, but little is known about its functions after completion of retinal differentiation. Therefore, we investigated PAX6 expression in wild-type and calcitonin receptor-like receptor transgenic (CLR(SMαA)) mice with angle-closure glaucoma.

Effect of the direct application of riboflavin and UVA on the Visian Implantable Collamer Lens.

Purpose: To report the effect of corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) on the optical and material characteristics of a posterior chamber phakic intraocular lens (Visian ICL, STAAR Surgical).

Methods: Optical and material characteristics were assessed in vitro, analyzing potential changes in riboflavin staining, dioptric power, transmission characteristics, and surface structure. A total of 9 lenses were analyzed: 3 lenses were irradiated with 0.

Experimental setup to determine the pulse energies and radiant exposures for excimer lasers with repetition rates ranging from 100 to 1050 Hz.

Purpose: To evaluate the feasibility of surface profiling for central ablation depth measurements and determine experimentally the required single-pulse energies and radiant exposures to achieve equivalent central ablation depths on bovine corneas for a myopic correction of -6.00 diopters (optical zone 6.5 mm) performed with laser repetition rates ranging from 100 to 1050 Hz.

Effect of time sequences in scanning algorithms on the surface temperature during corneal laser surgery with high-repetition-rate excimer laser.

Purpose: To investigate the influence of temporal and spatial spot sequences on the ocular surface temperature increase during corneal laser surgery with a high-repetition-rate excimer laser.

Setting: Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany.

Methods: An argon-fluoride excimer laser system working at a repetition rate of 1050 Hz was used to photoablate bovine corneas with various myopic, hyperopic, and phototherapeutic ablation profiles.

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.

Influence of spatial and temporal spot distribution on the ocular surface quality and maximum ablation depth after photoablation with a 1050 Hz excimer laser system.

Purpose: To investigate the effect of temporal and spatial distributions of laser spots (scan sequences) on the corneal surface quality after ablation and the maximum ablation of a given refractive correction after photoablation with a high-repetition-rate scanning-spot laser.

Setting: IROC AG, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany.

Methods: Bovine corneas and poly(methyl methacrylate) (PMMA) plates were photoablated using a 1050 Hz excimer laser prototype for corneal laser surgery.

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).

Corneal collagen crosslinking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ keratomileusis.

Purpose: To determine whether riboflavin and ultraviolet-A (UVA) corneal crosslinking can be used as an alternative therapy to prevent the progression of keratectasia.

Setting: Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland, and a private clinic, Athens, Greece.

Methods: Corneal crosslinking was performed in 10 patients with formerly undiagnosed forme fruste keratoconus or pellucid marginal corneal degeneration who had laser in situ keratomileusis (LASIK) for myopic astigmatism and subsequently developed iatrogenic keratectasia.

Corneal cross-linking-induced stromal demarcation line.

Purpose: Corneal collagen cross-linking by UVA/riboflavin (X-linking) represents a new method for the treatment of progressive keratoconus and currently is under clinical study. To avoid UVA irradiation damage to the corneal endothelium, the parameters for X-linking are set in a way that effective treatment occurs only in the first 300 microm of the corneal stroma. Here, X-linking not only strengthens the biomechanical properties of the cornea but also induces keratocyte apoptosis.

Customized ablation algorithm for the treatment of steep central islands after refractive laser surgery.

Steep central island (SCI) formation after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) represents a major drawback in the visual rehabilitation of patients after refractive laser surgery. Because of the small size of SCIs, current ablation algorithms are unable to properly calculate an ablation pattern for customized retreatment. We present the use of a new ablation algorithm for the treatment of SCIs that occurred after PRK or LASIK surgery.

Compound developmental eye disorders following inactivation of TGFbeta signaling in neural-crest stem cells.

Background: Development of the eye depends partly on the periocular mesenchyme derived from the neural crest (NC), but the fate of NC cells in mammalian eye development and the signals coordinating the formation of ocular structures are poorly understood.

Results: Here we reveal distinct NC contributions to both anterior and posterior mesenchymal eye structures and show that TGFbeta signaling in these cells is crucial for normal eye development. In the anterior eye, TGFbeta2 released from the lens is required for the expression of transcription factors Pitx2 and Foxc1 in the NC-derived cornea and in the chamber-angle structures of the eye that control intraocular pressure.