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.

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