1. Application of Quantitative Method for Prospectively Identifying Risk for Ectasia After LASIK in Normal, Suspect, and Ectatic Eyes
Mujtaba A. Qazi, MD
Pepose Vision Institute and
Department of Ophthalmology
Washington University School of Medicine
St. Louis, Missouri

2. Co-INVESTIGATORS: Pete Kollbaum, OD, PhD,1 Ashraf M
Co-INVESTIGATORS: Pete Kollbaum, OD, PhD,1 Ashraf M. Mahmoud,2 Michael Twa, OD, PhD,3 & Cynthia J. Roberts, PhD,2,5 Mohinder M. Merchea, OD, PhD,6 Jay S. Pepose, MD, PhD7,8
1. Indiana University, School of Optometry
2. The Ohio State University, Department of Ophthalmology
3. University of Houston, College of Optometry
4. The Ohio State University, Department of Biomedical Engineering
5. Bausch & Lomb
6. Pepose Vision Institute
7. Washington University School of Medicine, Department of Ophthalmology and Visual Sciences
Financial disclosures: Qazi: Alcon B; Allergan B Roberts: Reichert D,E; Ziemer A, D, E, P
Merchea: Bausch & Lomb Y Pepose: Bausch & Lomb A, D; Visiogen A

3. Purpose:
To compare the Randleman Ectasia Risk Factor (ERF) Score in populations with a clinical diagnosis of normal, suspect keratoconus, and kerectasia, including keratoconus and post-LASIK ectasia.

4. Design: Retrospective: chart review Keratoconus (KCN, n=36)
CLEK Study Criteria: Irregular Mires or Reflex; Vogt’s Striae or Fleisher ring or Apical scar
Fellow eye of Keratoconus (KCF, n=10)
No definite slit-lamp findings in study eye, with (+) CLEK criteria in contralateral eye
Keratoconus Suspect (KCS, n=44)
Topographic irregularity but no slit-lamp findings in either eye
Normal (n=32)
Post-LASIK Ectasia (n=9)

5. Design: Ectasia Risk Score Parameters Age Central Pachymetry (CCT)
Spherical Equivalent (SE)
Calculated Residual Stromal Bed (RSB)
120 micron flap for all eyes
14 microns/D of SE calculated for ablation (AD)
RSB = CCT - (120 + AD)
Topography

6. Methods: Randleman Ectasia Risk Factor (ERF) Scoring System
Age
Anterior & Posterior Elevation
Curvature (Axial, Mean, Tangential)
Pachymetry
Topography Grading System
1. Normal/symmetrical; includes round, oval, or symmetric bowtie patterns.
2. Suspicious; includes the following asymmetric patterns:
a. Asymmetric bowtie
i. Asymmetric steepening in any direction less than 1.0 D
ii. No skewed radial axis
b. Inferior steep/skewed radial axis
i. Significant skewed radial axis with or without inferior steepening, or
ii. One diopter or more of inferior steepening in some areas but an I-S value of less than 1.4.
3. Abnormal; includes keratoconus, pellucid marginal corneal degeneration, or forme fruste keratoconus with an I-S value of 1.4 or more.
Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery.. Ophthalmology Jan;115(1):37-50.

7. Randleman ERF Score
Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery.. Ophthalmology Jan;115(1):37-50.

8. ERF Scores MEAN SD RANGE MEDIAN
P VALUE comparing study group to NORMAL
NORMAL
1.67
1.76
0 - 6 1
Keratoconus Sustpect (no slit lamp lsigns in either eye but)
3.91
2.25
1 -9
4.0
<0.01
Keratoconus Fellow
(slit lamp signs in comtralateral eye only)
4.50
2.51
1 – 8
4.5
Keratoconus
(slit lamp signs in study eye)
9.08
4.29
3 – 16 8
Preop parameters of Post-LASIK Ectasia
2.33
1.00
1 - 3
0.23

9. RESULTS
In the KCNfellow (mean 2.60±1.43, range 1-4, median 3) and PLE (2.33±1.00, 1-3, 3) groups, only the topography score was statistically significantly higher (p<0.001) than in NRM (0.39±0.50, 0-1, 0).
In PLE, 66% of eyes had skewed asymmetry and 33% had an asymmetric bowtie.
Irregular topography (1.82±1.87, 0-4, 1, p<0.001) and younger age (p=0.01) scores were statistically higher in the KCS group compared to NRM.

10. SUMMARY
Application of the Randleman Ectasia after LASIK Risk Score in ectatic and suspicious eyes highlights the importance of topographic analysis in the preoperative assessment of the keratorefractive surgery candidate.
Differential weighting of the topography score may enhance the efficacy of ectasia risk analysis.
The relative risk of specific topographic features should be further quantified.