Strike Point System to Determine Candidacy for LASIK or PRK Lewis R. Groden, MD Monte Sichelman, MD The authors have no financial interests in any of the material in this presentation

Strike Point System to Determine Candidacy for Lasik or PRK Lewis R Groden MD, Monte Sichelman, MD Purpose: To present the Strike Point System (SPS) algorithm, a practice pattern codification, used to determine candidacy for lasik or prk, and compare this system to those published by Randleman and Tabbara. Methods: SPS has been applied to more than 13,000 patients over the past 3 years to determine candidacy for laser vision correction. Points are assigned based on age, pachymetry, topography pattern, Orbscan posterior float elevation, and the inferior- superior difference on the keratometric map. 0-1 strike per eye makes the patient a candidate for lasik, 2 strikes prk, and three or more strikes a non-candidate. SPS was compared to Tabbara’s and Randleman’s systems in 22 patients deemed to be non- candidates, 20 prk patients, and 26 lasik patients. SPS was also applied retrospectively to 13 cases of post-lasik ectasia. Results: For all three groups (non-candidate, prk, lasik) SPS and Randleman’s system were in excellent agreement for all patients. In Tabbara’s system most patients fell into the middle risk group. There was poor correlation between SPS/Randleman scores and the Tabbara score. For the ectasia cases, at least one eye of each patient had a SPS score of 3 or more strikes. Conclusions: SPS is a useful, easy to apply tool to help determine candidacy for lasik or prk. It is in good agreement with the system published by Randleman. Tabbara’s system is difficult to apply, places most patients in one risk group, and has poor agreement with SPS and Randleman.

Tabbara KF, Kotb AA Ophthalmology 2006; 113: Retrospective, comparative analysis of 37 patients who developed post lasik ectasia out of 148 myopic patients (SE -4 to -8 D) Retrospective, comparative analysis of 37 patients who developed post lasik ectasia out of 148 myopic patients (SE -4 to -8 D) (111 no ectasia age/gender matched controls) (111 no ectasia age/gender matched controls) 6 parameters, each given a grade 1 to 3 6 parameters, each given a grade 1 to 3 Total grade ≤ 7: no ectasia Total grade ≤ 7: no ectasia 8-12: 16/27 (59%) ectasia 8-12: 16/27 (59%) ectasia > 12: 21/21 (100%) ectasia > 12: 21/21 (100%) ectasia

Tabbara KF, Kotb AA Ophthalmology 2006; 113: Grade 1 Grade 2 Grade 3 Keratometry 47 Keratometry 47 Oblique Cylinder 1.5 Oblique Cylinder 1.5 Pachymetry > <500 Posterior surface 40 Posterior surface 40 elevation elevation I-S difference 1.4 I-S difference 1.4 Post BSF/Ant BSF 1.27 Post BSF/Ant BSF 1.27

SPS vs Tabbara Non candidates (topo): 22 patients Non candidates (topo): 22 patients PRK: 20 patients PRK: 20 patients LASIK: 26 patients LASIK: 26 patients Random, retrospective chart review Random, retrospective chart review

Strike Point SystemTabarra score# patientsscore# patients Non- candidate ≥322 > PRK 04* ≤ >121 LASIK ≤125≤ * secondary to occupation or inadequate residual stromal bed thickness

Randleman et al. Ophthalmology 2008; 115: 37-50

SPS vs Randleman Non-candidates 10 patients Non-candidates 10 patients PRK 15 patients PRK 15 patients Lasik 20 patients Lasik 20 patients Random, retrospective chart review Random, retrospective chart review

Strike Point SystemRandleman score# patientsscore# patients Non- candidate ≥310≥410 PRK215 ≥43 ≤312 LASIK≤ ≤219

Ectasia 13 patients 13 patients Retrospective review of submitted cases Retrospective review of submitted cases SPS: ≥ 3 strikes in at least 1 eye of each patient SPS: ≥ 3 strikes in at least 1 eye of each patient

Conclusions Tabbara et al. Tabbara et al. - article poorly defines parameters - article poorly defines parameters - not sensitive enough to be useful - not sensitive enough to be useful SPS has good agreement with system published by Randleman et al. SPS has good agreement with system published by Randleman et al. SPS is useful and easy to apply SPS is useful and easy to apply