Myoring Versus Keraring Implantation for Keratoconus

Study Overview
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Brief Summary
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Various approaches, including surgical and non-surgical management have been proposed for keratoconus. One of the surgical procedures is Intrastromal Corneal Ring implantations that have been designed to achieve refractive readjustment by flattening the cornea. There are different models of Intrastromal Corneal rings available: intrastromal corneal ring segments (ICRS) such as Keraring and intrastromal corneal continuous ring (ICCR) like Myoring. Most studies of these two types of ring implantation outcomes are retrospective case series. Thus, this Randomized Clinical Trial study was designed with the aim of Comparing visual and refractive outcomes and complications of insertion Myoring versus Keraring using Femtosecond laser. Keratoconus patients with compound myopic astigmatism who meet the inclusion criteria will randomly allocated to the Keraring and Myoring groups. Subsequently, the clinical outcomes of two groups will be compared at one,3 and 6 months after surgery.

Conditions
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Keratoconus

Intervention / Treatment
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* Other: intrastromal corneal ring segments (Keraring) implantation
* Other: Intrastromal corneal continuous ring (Myoring) implantation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: keratoconus patients and : age between 20 to 40 corneal thickness> 380 microns mean keratometry between 44 to 60 D clear central cornea Patients should be discontinued their contact lenses for 3 weeks prior to the exams contact lenses in tolerance 20/200<visual acuity <20/30 Exclusion Criteria: Positive pregnancy test Breast-feeding History of glaucoma, cataract, vernal and atopic keratoconjunctivitis History of previous ophthalmologic surgery, keratorefractive surgery on the operative eye Dry eye Corneal stromal disorders History of herpetic keratitis Pellucid marginal degeneration Corneal grafts Retinal disorders Nystagmus and uncooperative disposition Neuro-ophthalmologic disorders Intraocular pressure <10 mmHg or >21 mmHg Patients with autoimmune, connective tissue disorders, diabetes and immunosuppressive drugs users Hyperopia

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Intrastromal corneal continuous ring (Myoring)<br> | Other: Intrastromal corneal continuous ring (Myoring) implantation<br> <br> |
| Active Comparator: Intrastromal corneal ring segments (Keraring)<br> | Other: intrastromal corneal ring segments (Keraring) implantation<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| uncorrected visual acuity | Snellen E chart | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Corneal thickness | Galilei Dual Scheimpflug Analyzer ( Ziemer, Switzerland) | 6months | 
| Corneal irregularities (3, 5 and 7 mm of central cornea) | Galilei Dual Scheimpflug Analyzer ( Ziemer, Switzerland) | 6 months | 
| Front & back corneal elevation | Galilei Dual Scheimpflug Analyzer ( Ziemer, Switzerland) | 6 months | 
| Corneal aberrometry | Galilei Dual Scheimpflug Analyzer ( Ziemer, Switzerland) | 6 months | 
| Corneal eccentricity | Galilei Dual Scheimpflug Analyzer ( Ziemer, Switzerland) | 6 months | 
| Corneal hysteresis & corneal resistance factor | Ocular response Analyzer (reichert ophthalmic instruments, Buffalo,New York ,USA) | 6 months | 
| Intra and postoperative complications (glare, night vision problem, migration, extrusion, infection) | clinical examination, patients history | Intra and post operatien |