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. Author manuscript; available in PMC: 2019 Apr 2.
Published in final edited form as: Curr Opin Ophthalmol. 2017 Jul;28(4):337–342. doi: 10.1097/ICU.0000000000000383

Table 2.

Randleman et al. Ectasia Risk Score System (ERSS) [5].

Risk Factors
(in order of
significance)		 Score
0
(low risk)		 1
(low risk)		 2
(low risk)		 3
(moderate
risk)		 4
(high risk)
Preop topography Symmetrical bowtie Asymmetric bowtie (asymmetric steepening in any direction less than 1.0 D) Inferior steepening; skewed radial axis (significant skewed radial axis with or without inferior steepening, I-S value less than 1.4 D) Keratoconus; pellucid marginal degeneration; forme fruste keratoconus with I-S value of 1.4 or more
Residual stromal bed (RSB) thickness (μm) >300 280-299 260-279 240-259 <240
Age >30 26-29 22-25 18-21
Preop corneal thickness (μm) >510 481-510 451-480 <450
Preop spherical equivalent manifest refraction (D) −8 or less > −8 to −10 > −10 to −12 > −12 to −14 > −14