Keratoconus is a corneal degenerative disease associated with loss of best-corrected visual acuity. The use of intrastromal corneal ring segment implants is indicated to regularize the cornea and to reduce aberrations.

Keratoconus is a corneal degenerative disease characterized by corneal thinning and subsequent development of irregular astigmatism, diminution of vision and loss of best-corrected visual acuity.

Management of keratoconus includes halting disease progression through a corneal strengthening procedure called corneal collagen cross-linking (CXL) which usually results in stabilizing the condition but with no improvement in visual acuity or quality. Intrastromal corneal ring segment (ICRS) implantation is a well-established procedure for the management of moderate keratoconus with a corneal flattening effect that is associated with improvement of visual acuity and reduction of optical aberrations.

The aim of the study is to evaluate and compare the visual, refractive and topographic outcomes of two different femtosecond laser assisted surgical techniques to create a corneal stromal pocket or a tunnel for implantation of ICRS for the management of central keratoconus

Inclusion Criteria:

1. Patients with progressive keratoconus with maximum keratometry (Kmax) between 50-65 diopters
2. Central keratoconus (Keratoconus with steepest corneal point within the central 3 mm zone).
3. Clear corneal with a minimum pachymetry of 400 μm.

Exclusion Criteria:

1. Corneal scars
2. Patients with advanced keratoconus with Kmax > 65 diopters.
3. Non-central keratoconus (para-central or peripheral keratoconus with steepest corneal point outside the central 3 mm zone).
4. Previous corneal cross-linking and/or ocular surgery.
5. Systemic diseases such as diabetes mellitus and autoimmune diseases