Comparing the Postoperative Outcomes of Intrastromal Corneal Ring Segments in Three Different Topographic Patterns of Eccentric Keratoconus

PURPOSE: To compare the postoperative outcomes following implantation of KERATACx ring segments (Imperial Medical Technologies Europe GmbH) in patients having eccentric keratoconus with three different topographic patterns.<br /> METHODS: This retrospective cohort study was conducted at Maadi Eye Subspeciality Center, Cairo, Egypt. The study included patients with keratoconus who had implantation of KERATACx ring segments. Three groups were segregated based on topographic keratoconus patterns using the Sirius CSO Topographer (CSO Italia): type I ectasia where the cone coincides with the corneal flat axis, type II ectasia in which the cone coincides with neither the steep nor the flat axis and lies between the two axes, and type II ectasia for cones coinciding with the corneal steep axis. The visual and topographic outcomes were compared preoperatively and postoperatively for the three enrolled groups.<br /> RESULTS: This study enrolled 92 eyes of 92 patients and had a mean +/- standard deviation follow-up of 16.9 +/- 9.2 months. The patients' medical records revealed that night vision complaints and halos around the light were experienced the most by the type III ectasia group (31.25%). For the type III ectasia group, four topographic indices and one visual parameter did not show statistically significant differences between the preoperative and postoperative data (inferior-superior difference at 2- and 4-mm diameter, coma aberration, higher order aberrations, and uncorrected distance visual acuity), contrary to the type I and II ectasia groups, which showed significant improvements in all evaluated parameters. CONCLUSIONS: The type III morphological pattern of ectasia is the least likely to benefit from KERATACx ring segments implantation.