Intrastromal corneal ring segment implantation in 219 keratoconic eyes at different stages

To evaluate the visual and refractive outcomes of intrastromal corneal ring segment (ICRS) in keratoconic eyes at different stages.

Two hundred and nineteen keratoconic eyes were divided into three groups as a function of stage of keratoconus (stages I, II and III). There were 115 eyes with stage I, 84 eyes with stage II and 20 eyes with stage III. Snellen uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (CDVA), and residual refractive errors analyzed using vector analysis were recorded before surgery and 6 months post-surgery.

For stage I, UDVA changed from 0.26 ± 0.19 pre-surgery to 0.58 ± 0.30 post-surgery (P < 0.001) and CDVA from 0.79 ± 0.19 to 0.90 ± 0.13 (P < 0.0001). For stage II, UDVA was 0.17 ± 0.15 pre-surgery and 0.35 ± 0.22 post-surgery (P < 0.001) and CDVA changed from 0.56 ± 0.21 to 0.67 ± 0.20 after the surgery (P < 0.0001). For stage III, statistically significant differences both for UDVA and CDVA were not found (P = 0.08 and P = 0.01 respectively). For stage I, 52.16% of the eyes gained lines of CDVA, 39.13% did not change their CDVA, and 8.67% lost lines of CDVA. For stage II, 65.48% of the eyes gained lines of CDVA, 20.24% had unchanged CDVA, and 14.28% lost lines of CDVA. For stage III, 60% of the eyes gained >2 lines of CDVA, 25% did not change their CDVA, and 15% lost lines of CDVA. A significant decrease in the spherical equivalent after surgery was found for stages I and II (P < 0.0001) but not for stage III (P = 0.07).

ICRS implantation is an effective procedure for keratoconus treatment, being more effective for moderate keratoconus.