Donors Predisposed by Corneal Collagen Cross-linking in Deep Lamellar Keratoplasty for the Patients With Keratoconus

Study Overview
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Brief Summary
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The Study was designed as a randomized controlled study with the following objectives: To investigate whether use of donors predisposed by corneal collagen cross-linking (CXL) reduced myopic refractive errors for keratoconic eyes after Deep anterior lamellar keratoplasty (DALK). Overall 70 patients are planned to recruit., the patients were assigned to CXL graft group, in which corneal donors predisposed by CXL were used, or the conventional graft group, in which corneal donors stored in corneal storage media were used. The patients will be followed-up for 24 months.

Detailed Description
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Keratoconus is a progressive ecstatic corneal disease characterized by forward bulging of the cornea, thinning of the corneal stroma, and irregular astigmatism. Corneal transplantation is necessary for patients with advanced keratoconus when spectacles and contact lens are inadequate for visual correction. Deep anterior lamellar keratoplasty is a conventional procedure for the treatment of keratoconus. However, DALK itself frequently causes abnormality of refraction, such as high degrees of astigmatism owing to irregular corneal surface for keratoconic eyes. Possible mechanisms of this progressive astigmatism include the recurrence of keratoconus in the grafts, progressive corneal thinning of the host cornea, or progressive misalignment of the graft- host interface over time, which prevents the achievement of satisfactory vision. Corneal collagen cross-linking is believed to have the ability to halt or decrease the progression of keratoconus. CXL treats keratoconus by strengthening corneal stromal collagen bonds with riboflavin activated by ultraviolet A (UVA), and is now a first-line treatment for progressive keratoconus. In this randomized controlled trial, we performed CXL on corneal donor tissues with the aim of achieving corneal stromal stiffening, thereafter DALK was conducted for the patients with advanced keratoconus using the tissues predisposed by CXL. The goal of this study is evaluating whether the strengthening grafts could reduce postoperative myopic refractive errors or arrest the progression of keratoconus for the patients with DALK.

Official Title
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Effectiveness and Safety of Donors Predisposed by Corneal Collagen Cross-linking in Deep Lamellar Keratoplasty for Treating the Patients With Keratoconus，A Randomized Controlled Trial.

Conditions
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Keratoconus

Intervention / Treatment
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* Procedure: Corneal donors predisposed by CXL
* Procedure: Corneal donors stored in corneal storage media


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1.The best corrected visual quality of frame glasses is less than 0.3，2.The best corrected visual quality of rigid gas permeable contact lens (RGPCL) is less than 0.5/ RGPCL intolerance，3.The anterior corneal surface curvature >55D，4.The thinnest corneal thickness is less than 400 μm. One of the above four items is met Patients must be willing and able to return for scheduled follow-up examinations for 36 months after surgery Ages：over 18 Years Exclusion Criteria: History of intraocular surgery Severe dry eye Severe eyelid and conjunctival scar Loss of vision in contralateral eye Pregnant and lactating women

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 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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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: CXL graft group<br>Corneal donors predisposed by CXL were used and the conventional DALK procedure was conducted in patients | Procedure: Corneal donors predisposed by CXL<br>* Corneal donors predisposed by CXL and DALK procedure was conducted in patients<br>|
| Active Comparator: Conventional graft group<br>Corneal donors stored in corneal storage media were used and the conventional DALK procedure was conducted in patients | Procedure: Corneal donors stored in corneal storage media<br>* Corneal donors stored in corneal storage media and DALK procedure was conducted in patients<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Simulated keratometry | Simulated keratometry measured by topography | up to 36 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Uncorrected distance visual acuity（UDVA） | UDVA (by using Snellen acuity charts) before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after surgery | 36 months | 
| Corrected distance visual acuity （CDVA） | CDVA (by using Snellen acuity charts) before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after surgery | 36 months | 
| Spherical equivalent (SE) | SE will be detected by combined optometry and phoroptor refractometer before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after surgery | 36 months | 
| Manifest cylinder | Manifest cylinder will be detected by topography before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after surgery | 36 months | 
| Corneal thickness | Corneal thickness of the thinnest area will be detected by Optical Coherence tomography before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after surgery | 36 months | 
| Corneal endothelium cells | Corneal endothelium cells will be detected by confocal microscopy before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24 ,30 and 36 months after surgery | 36 months | 
| Intraocular pressure | Intraocular pressure was measured by non-contact tonometer before surgery, at 1 week, 1, 3, 6, 9, 12, 15, 18, 21, 24,30 and 36 months after surgery | 36 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Corneal collagen cross-linking, Deep lamellar keratoplasty, Keratoconus