Background: Corneal ectasia is a sight-threatening complication of excimer laser refractive surgery with progressive thinning of the cornea, estimated between 0.04% and 0.6%. Aim of the work: Evaluate the sensitivity, specificity, and accuracy of ectasia risk score system and the practical subjective scoring system in screening keratorefractive surgery candidates. Patients and methods: This retrospective study was included 226 eyes at Ebsar Eye Center, Benha, Egypt, subjects divided into 5 groups based on preoprative Pentacam and prevalence of post lasik ectasia. Group 1-2 included 100 eyes, group 3 no eyes found to meet it, group 4 included 4 eyes, group 5 included 22 eyes. Group 1 : Patients with grade 1 keratoconus, were not enrolled in keratorefractive surgeries. Group 2 : had normal tomography, were enrolled for keratorefractive surgeries, and no postoperative ectasia. Group 3: Preoperative normal tomography, had keratorefractive surgeries, with postoperative ectasia. Group 4 : preoperative abnormal tomography, had keratorefractive surgeries, with ectasia. Group 5: had abnormal tomography with keratorefractive surgeries, with ectasia. Complete ophthalmological examination including auto refractometer and subjective refraction examination, Slit lamp bio microscopy, ophthalmoscopy. Corneal topography done by Pentacam HR, and repeated twice for each eye. Topographic analysis was obtained for each eye. Results: Positive correlations between groups regarding PS3 Thinnest local, preop thickness, profile map shape, inter eye interpretation score, preop Ant Km, no significant differences regarding PS3 Ant Km. Conclusion: Both ERSS and PS3 are sensitive, specific, and accurate in screening keratorefractive surgery candidates. Keywords: Ectasia, PS3, score, ERSS, keratorefractive.