Purchase this article with an account.
Marianella Delrivo, Jonatán D. Galletti, Fernando Fuentes Bonthoux, Tomás Pförtner, Jeremias G. Galletti; Comparative Diagnostic Performance of Pentacam Scheimpflug Tomography and Ocular Response Analyzer Measurements for Subclinical Keratoconus. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6798.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare the diagnostic performance of the Pentacam Scheimpflug tomograph and Ocular Response Analyzer (ORA) for healthy and subclinical keratoconus eyes.
19 eyes from 19 healthy subjects in group 1 and 30 eyes from 30 unilateral manifest keratoconus patients in group 2 were evaluated with corneal topography, Pentacam tomography and ORA. The eye with the lowest average corneal power (ACP) was recruited in group 2. Pentacam reported indices for posterior corneal elevation (Db), pachymetric progression (Dp) and overall keratonus findings (D) and previously defined ORA-derived biomechanical measurements DifCRF (CRF corrected for central corneal thickness) and CH-CRF were compared between groups.
The two groups were not different in mean age (years, 30.9±10.6 vs 31.3±12.2) or central corneal thickness (µm, 512.6±26.0 vs 496.9±34.6) but ACP was higher in group 2 eyes (diopters, 43.90±1.93 vs 45.66±3.17, p<0.05, Student’s t test). Pentacam’s Db, Dp and D indices (positive > 2) had 94.7%, 89.5% and 89.5% specificity and 50.0%, 50.0% and 66.7% sensitivity, respectively. ORA’s DifCRF (positive < -0.695).and CH-CRF (positive > 0.95) indices showed 78.9% and 57.9% specificity and 86.7% and 53.3% sensitivity, respectively. Either D or DifCRF indices were positive in 93.7% of group 2 eyes, with 68.4% combined specificity.
ORA-derived index DifCRF has higher sensitivity for subclinical keratoconus eyes but falsely flags healthy corneae more often than Pentacam’s indices, which on the other hand show high specificity. An approach combining both methods could markedly increase sensitivity while sacrificing some specificity, a probably acceptable tradeoff in the screening of refractive surgery candidates.
This PDF is available to Subscribers Only