Keratoconus progression after intrastromal corneal ring segment implantation according to age: 5-year follow-up cohort study

Intrastromal corneal ring segments (ICRS) have been found to be useful in correcting keratoconus by decreasing irregular astigmatism, thereby potentially improving visual acuity. However, its long-term effects in keratoconus progression are not completely understood, mainly concerning the effects of age on ICRS implantation results. This study aimed to evaluate long-term effects of ICRS implantation according to age at implantation.

We conducted a longitudinal retrospective study, where we evaluated patients with keratoconus who underwent ICRS implantation between 2004 and 2012.

We evaluated 34 eyes for 5 years post-operatively. The mean age of the 21 men and 7 women was 20.59 ± 4.65 years. Best spectacle-corrected visual acuity (BSCVA) improved from 0.32 ± 0.19 in the preoperative period to 0.46 ± 0.27 6 months post-operatively. After up to 5 years of follow-up, there was no significant difference in mean visual acuity of the group. As expected, there was a significant decrease in keratometric values after corneal ring implantation, which remained stable over the 5-year follow-up. Among the 34 cases analysed, nine (26%) showed signs of disease progression. In eight of the nine documented progression cases, patients were 21 years old or younger, revealing that these patients were sevenfold more likely to progress than those aged over 21 years.

In our series of cases, ICRS implantation was shown to be an excellent treatment to reduce corneal curvature and improve visual acuity at all ages, but it did not stabilize the disease, especially in young patients with more aggressive forms of the keratoconus.