Active clinical trials for "Keratoconus"

Cross-linking of the cornea increases the mechanical and biochemical stability of the stromal tissue. The purpose of this study is to assess the effectiveness of riboflavin-ultraviolet light induced cross-linking of corneal collagen in improving visual acuity and reducing progression of keratoconus in the Brazilian population.

The purpose of this study is to determine the effectiveness of collagen cross-linking in the cornea in halting the progression and possibly partially reversing the effects of keratoconus. Keratoconus is a progressive weakening in the cornea that causes irregular astigmatism and thinning of the cornea. The overall effect is reduction of vision, and in more advanced cases, scarring of the cornea that may lead to the need for corneal transplantation. Cross-linking has been shown increase the rigidity of the cornea. The patients would be treated once and then followed over 24 months. .

Young patients with keratoconus face two problems: disease progression and corneal shape irregularity. Both underlie the 20% rate of corneal transplantation in keratoconics required to maintain useful vision. Corneal collagen cross-linking (CXL) is a now the gold-standard treatment to halt disease progression. The aim is to strengthen the cornea to prevent further shape deterioration. For patients whose quality of vision has already suffered, standard CXL can generally only prevent further deterioration, rather than improving vision. Refractive CXL, a new iteration of CXL in which a bespoke treatment pattern is applied to the cornea, aims to smooth out surface irregularities thereby improving vision. This primary objective of this study is to compare the visual outcome in patients with progressive keratoconus treated with refractive CXL, as compared with historical controls treated with standard CXL.

This prospective, randomized study is being conducted to evaluate the safety and effectiveness of corneal cross-linking (CXL) in patients with keratoconus or post-refractive ectasia (post-LASIK or PRK) utilizing two techniques: the "standard" Epi-Off technique or an Epi-On technique that utilizes iontophoresis (I-CXL) to deliver the riboflavin to the cornea without need for removal of the corneal epithelium. Patients will be randomized to receive CXL treatment with either the Epi-On or Epi-Off technique.

The purpose of this study is to investigate changes in the corneal thickness of scleral contact lens wearers in a keratoconic (KC) population and compare to age-matched controls. The hypothesis is that scleral contact lens wear is associated with low levels of corneal hypoxia including measurable changes in corneal thickness. Corneal thickness will be altered post scleral lens wear compared to pre-lens wear and the amount of alteration will correlate to the fitting characteristics in the central zone of the scleral lenses. We propose to take a sample of keratoconic and control participants, fit them in scleral lenses, and to measure topographic corneal thickness after 8-10 hours of scleral lens wear after three weeks of wear, to compare two instruments in the measurement of corneal thickness, and to compare the effects of varying central corneal clearance of the scleral lens on corneal thickness.

The purpose of this study is to evaluate the efficacy of ultraviolet-A (UVA)-induced cross-linking of corneal collagen (CXL) as a method to increase the biomechanical and biochemical stability of the cornea by inducing additional cross-links within or between collagen fibers using UVA light and the photo- mediator riboflavin. The purpose of this study is to generate data for presentation at medical meetings and for peer-review publication. The data generated by this study will not be submitted to the FDA to support commercialization of these riboflavin drops.

The purpose of this study is to assess safety, efficacy and stability of riboflavin-UV induced cross-linking of corneal collagen in reducing the progression of keratecatasia and in improving visual acuity. This is the first Norwegian study concerning CCL.

Background: The objective of corneal collagen crosslinking (CXL) is to increase the binding of intrafibrillary and interfibrillary covalent bonds to improve the mechanical stability of the cornea and thus to stop the progression of corneal ectasias. Although the vast majority of studies have described pain after photorefractive keratectomy (PRK), the pathophysiological principle of pain is similar in CXL. From the anatomical point of view, the corneal epithelium is the most densely innervated and sensitive surface of the body, being 300-600 times greater than in the skin. The pain after CXL comes from several routes, the process begins with the epithelial rupture that generates exposure of the nerve endings, induces apoptosis and necrosis of the epithelial cells. Subsequently an inflammatory cascade is initiated in which the different cytokines stimulate the nerve terminals. Inflammatory mediators also activate the ion channels in the nerve membrane, and this process continues until the epithelium heals. Additionally, exposure to UVA rays can also cause nerve damage. The effect of local cold for pain management has already been reported in PRK. By cooling the cornea, the release of chemical mediators and inflammation can be reduced. In the CXL radiation is transformed into several forms of energy: fluorescent radiation, chemical energy and, to a small extent, heat. The CXL process is energetically comparable to photosynthesis, in which the radiation energy is transformed into chemical energy (glucose) with the help of pigments (chlorophyll). The thermal effect is negligible in the photochemical method of CXL. Justification: No method for the control of pain after crosslinking is considered ideal or universally accepted, the importance of this study lies in looking for an additional tool to reduce the most common postoperative complaint in a highly performed procedure worldwide. Hypothesis: The application of riboflavin at 4oC reduces the pain assessment after the CXL. Purpose: to evaluate the effect of the application of riboflavin at 4oC in the assessment of postoperative pain in patients undergoing CXL. Materials and methods: Prospective and interventional clinical study in patients older than 18 years with a diagnosis of keratoconus who underwent CXL, in the cornea and refractive surgery service of the Ophthalmology institute Fundación Conde de Valenciana.

This pilot study will compare upto 15 patients undergoing femtolaser assisted keratoplasty (using CE[Conformité Européene] approved femtolaser apparatus) with upto 15 patients undergoing conventional keratoplasty with a manual trephine. Patients will be randomly assigned to either group. All keratoplasties will be penetrating keratoplasties. The following aims of this research is detailed below: Does femtosecond laser assisted keratoplasty ( FLAK ) yield faster visual recovery and better long term BCVA (Best Corrected Visual Acuity)? Does FLAK offer a biomechanically stronger cornea and thereby more safety and less risk of wound dehiscence? Is there any difference between FLAK and conventional keratoplasty in terms of graft failure or rejection? Follow up in best corrected visual acuity, various refraction/astigmatism measurements, intraocular pressure, graft rejection/failure rates, pachymetry and corneal hysteresis and resistance factor will be recorded at 1 day, 1 week, 1, 3 and 6 months and 1 year and 18 months postoperatively. This study, to the investigators' knowledge will be the first randomised controlled trial in this area, the first to provide an empirical measurement to biomechanical stability of the cornea with the femtolaser, and the first done in an NHS (National Health Service) setting.

Keratoconus is a corneal ectatic disease responsible for a loss of visual acuity when the steepening increases. Corneal collagen crosslinking (CXL) is a procedure that appears to halt or slow down the progression and avoid the visual impairment. However, such a technique requires the epithelium debridement, wich can be responsible for severs complications. This study evaluate the safety and efficacy of transepithelial corneal crosslinking with oxygen to halt or slow down the progression of keratoconus. Such a procedure avoids the epithelium debridement and the related complications.