Abstract
Keratoconus is degenerative, non-inflammatory corneal disease. Primary keratoconus treatment is corneal collagen cross-linking (CXL) to stabilize coning. Additional therapy as intra-corneal rings segment (ICRS) required improving visual acuity. This study aimed to evaluate refractive outcomes and pachymetric changes of combined simultaneous ICRS and CXL on one session (Simultaneous) versus two sessions (Sequential). This Prospective Intervention Comparative Study included forty patients (60 eyes) with mild to moderate KC. Patients sorted into 2 groups: Simultaneous group includes 21 KC patients (30 eyes) undergo two procedures (ICRS then CXL) at same session and Sequential group includes 19 KC patients (30 eyes) undergo ICRS then CXL on two sessions with 3-4 weeks. Patients followed up at end of 1st, 3rd and 6th months. Assessment included changes in uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive errors sphere and cylinder, and Pachymetry. Improvement of UCVA, Sphere and Cylinder mean in Simulations and Sequential groups occurred at postoperative period at end of 1st; 3rd and 6th month; while BCVA values significantly improvement at postoperative period at end of 3rd and 6th month versus preoperative value. In conclusion, combined ICRS and CXL performed effectively in one or two sessions.

Key words:
corneal collagen crosslinking, ectasia, femtosecond laser, intracorneal ring segments insertion, keratoconus, refractory error, sequential, simultaneous