Comparative Results in a Combined Procedure of Intrastromal Corneal Rings Implantation and Cross-linking in Patients with Keratoconus: A Retrospective Study

Corneal thinning disorders caused by keratoconus often lead to protrusion, irregular astigmatism, and even perforation. Keratoconus, like other corneal ectasia, does not have a known cause. Severe cases of keratoconus may require correction or restoration of tectonic integrity of the cornea by surgical means. Intracorneal ring segments are a new modality in the treatment of corneal ectactic disorders. A new technique of stopping the evolution of keratoconus and strengthening the cornea is combining techniques of intrastromal corneal ring implantation and corneal collagen cross-linking. The objective of the study is to compare the effectiveness of combined procedures: intrastromal corneal ring implantation followed by cross-linking, with cross-linking followed by intrastromal corneal ring implantation. The study comprised two groups of patients with different evolutionary stages of keratoconus, which met the eligibility criteria for intrastromal corneal ring segment implantation and corneal collagen cross-linking. Group 1 included patients (41 eyes) who underwent intrastromal corneal ring implantation followed by cross-linking and group 2 (30 eyes) included patients who underwent cross-linking first followed by intrastromal corneal ring implantation. A decrease in Km values of about 1.5 D and refraction was observed in group 1, compared to a decrease in Km values of about 1 D and refraction in group 2. Recovery of visual acuity was higher in group 1 than group 2. The sequence of intrastromal corneal ring implantation followed by cross-linking proved to be more effective in reducing Km values, spherical equivalent and cylinder compared with cross-linking followed by intrastromal corneal ring implantation.