Assessment of Corneal Endothelium After Collagen Cross Linking

Study Overview
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Brief Summary
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The aim of this study is to assess the effect of accelerated corneal collagen cross linking on corneal endothelium using the specular microscopy

Detailed Description
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Keratoconus (KC) is a progressive, non-inflammatory corneal degenerative disease. It is a pathology characterized by a progressive thinning and protrusion of the cornea that ends in a cone-shaped cornea. This results in progressive myopia and irregular astigmatism with associated progressive loss of vision and thus reduced quality of life.Collagen cross-linking (CXL) is a relatively new conservative approach for progressive corneal ectasia. The main indication for CXL is to slow the progression of corneal ectatic diseases, such as keratoconus, pellucid marginal degeneration (PMD), keratoglobus and iatrogenic ectasia.The basic principle of this method is the chemical interaction of ultraviolet A radiation (315-400nm ) and riboflavin to induce covalent bond formation between collagen fibers of the cornea. In this way, the stiffness and rigidity of the cornea are provided.Corneal collagen cross-linking (CXL) was first introduced by Wollensak with an ultraviolet-A (UVA) protocol of 3 medium wave mW/cm2 intensity at 370 nm over an exposure time of 30 minutes (now termed the Dresden protocol). Researchers have proposed accelerated CXL (ACXL) protocols, to improve convenience and comfort for patients. These ACXL protocols have the aim of decreasing UVA exposure time by increasing UVA fluency to achieve the same overall total UVA dosage.Despite corneal CXL is a safe and effective procedure with few known side effects .Persistent corneal edema and possible endothelial cell damage have been reported in a few cases after CXL. Based on the extent of endothelial damage, patients may require penetrating keratoplasty.

Official Title
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A Specular Microscopic Study of Corneal Endothelium After Accelerated Corneal Collagen Cross Linking

Conditions
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Accelerated Corneal Collagen Cross Linking

Intervention / Treatment
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* Device: specular microscopy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1. patients with mild to moderate corneal ectasia who are candidates for CXL. Exclusion Criteria: patients with advanced corneal ectasia with maximum keratometry readings <56 diopters. corneal pachymetry >380um. corneal scarring. previous corneal surgeries (e.g intrastromal corneal ring segments)

Ages Eligible for Study
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Minimum Age: 16 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Device: specular microscopy|An informed written consent will be obtained from all patients that will be included in this study. Patients in this study will undergo specular microscopic examination of corneal endothelium before CXL procedure. Patients will be assigned to undergo accelerated (epithelium-off ,transepithelial ) CXL . Follow up specular microscopy will be done 3 months and 6 months after corneal collagen cross linking procedure .|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| endothelial cell count by specular microscopy. | specular microscopy will be used to assess corneal endothelial cell count after accelerated corneal collagen cross linking | from preoperatively to 6 months postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| endothelial cell morphology by specular microscopy. | specular microscopy will be used to assess corneal endothelial cell morphology after accelerated corneal collagen cross linking | from preoperatively to 6 months postoperatively |