External analysis of the Randleman Ectasia Risk Factor Score System: a review of 36 cases of post LASIK ectasia

Background: To validate Randleman's model of ectasia risk factor scores using a large unbiased sample of unpublished cases. Methods: Data were collected retrospectively on 36 eyes with ectasia post laser in situ keratomileusis treated by two surgeons at Vision Eye Institute. The data were then entered into Randleman's risk factor score system. Data were also collected about posterior maximum elevation (PME) and posterior maximum elevation position (PMEP); and these were compared with a control group of 50 eyes. Results: Of the 36 eyes, 9 (25%) were classified as low risk, 7 (19%) as moderate risk and 20 (56%) as high risk. On average, the most points were scored in the topography and topography was abnormal in 69% of cases. Topography points also correlated the most strongly with the increasing risk scores (P < 0.0001). PME or PMEP was not significantly different between our ectasia group and the control group. Conclusion: Randleman's ectasia risk factor scale can miss a significant proportion of patients at risk of ectasia. Other factors must play a role in ectasia risk. Abnormal corneal topography appears to be the most important preoperative risk factor.