Keratoconus (KC) is a bilateral asymmetric progressive corneal degenerative disease associated with corneal thinning and protrusion. The management of moderate progressive keratoconus involves halting its progression through corneal cross-linking as well as flattening of the ectatic steep cornea through the implantation of intrastromal corneal rings (ICR). Different nomograms were used to guide ophthalmic surgeons for the proper choice of ICR implantation to achieve the best results. The aim of the current study is to assess the visual, refractive and tomographic outcomes of Keraring implantation based on the Alfonso nomogram, in patients with keratoconus.

Inclusion Criteria:

• Patients aged between 18-35 years.
• Patients diagnosed with progressive keratoconus.
• Mean keratometry (Km) between 48-60 D.
• Clear cornea

Exclusion Criteria:

• Mild or advanced keratoconus
• Corneal scarring.
• Other corneal or ocular diseases.
• Systemic diseases such as diabetes mellitus and autoimmune diseases.