April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Concordance between corneal biomechanical testing and Scheimpflug tomography for keratoconus detection
Author Affiliations & Notes
  • Pablo Raul Ruisenor Vazquez
    Ophthalmology, Hospital de Clínicas, University of Buenos Aires, Buenos Aires, Argentina
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Jonatan David Galletti
    Ophthalmology, Hospital de Clínicas, University of Buenos Aires, Buenos Aires, Argentina
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Natalia Ximena Minguez
    Ophthalmology, Hospital de Clínicas, University of Buenos Aires, Buenos Aires, Argentina
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Marianella Delrivo
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Fernando Fuentes Bonthoux
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Tomas Pförtner
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Jeremias Gaston Galletti
    ECOS (Clinical Ocular Studies) Laboratory, Buenos Aires, Argentina
  • Footnotes
    Commercial Relationships Pablo Ruisenor Vazquez, None; Jonatan Galletti, None; Natalia Minguez, None; Marianella Delrivo, None; Fernando Fuentes Bonthoux, None; Tomas Pförtner, None; Jeremias Galletti, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3717. doi:
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      Pablo Raul Ruisenor Vazquez, Jonatan David Galletti, Natalia Ximena Minguez, Marianella Delrivo, Fernando Fuentes Bonthoux, Tomas Pförtner, Jeremias Gaston Galletti; Concordance between corneal biomechanical testing and Scheimpflug tomography for keratoconus detection. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3717.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To evaluate the concordance between Scheimpflug tomography and Ocular Response Analyser (ORA) testing in topographically unremarkable corneas for keratoconus detection

 
Methods
 

Observational case series of 206 eyes of 206 refractive surgery candidates evaluated with corneal topography for inclusion (only eyes with average corneal power power [ACP]≤47.75 D and corneal higher-order aberrations [HOA]≤0.650 µm) and then analyzed with Scheimpflug tomography (OCULUS Pentacam HR, Optikgeräte GmbH, Germany) and biomechanical testing (Ocular Response Analyzer, Reichert Ophathalmic Instruments, Depew, NY). Main outcome measurements were the Pentacam’s ectasia detection indices (Df, Db, Dp and D, cutoff ≥1.6) and previously validated combinations of ORA measurements (DifCRF and LF2, J Refract Surg. 2013 Sep;29(9):596-602). Statistical significance was set at p<0.05.

 
Results
 

Mean age (±SD) was 32.5±8.0 years and 43% of the subjects were male. Mean average corneal power was 44.5±1.5 D, HOA 0.263±0.093 µm, Df 0.53±1.11, Db -0.15±0.92, Dp 0.51±0.94, D 0.98±0.89, DifCRF 0.08±1.58 mm Hg and LF2 0.27±0.26. Actual positive rate (%) was Df 16.5, Db 5.3, Dp 10.2, Dt 11.2, Dy 10.2, D 21.8, DifCRF 30.6 and LF2 20.4. HOA were positively correlated with ACP (r=0.157, p=0.02), Dy (r=0.191, p=0.01), D (0.153, p=0.03) and LF2 (0.146, p=0.04). Concordance (both tests either positive or negative) was 62.1% for D and DifCRF, 68.4% for D and LF2, 66% for Dp and DifCRF and 76.2% for Dp and LF2. Only D-LF2 and Dp-LF2 double-positive cases had significantly (p<0.01) higher HOA (0.367±0.154 and 0.412±0.172 µm, respectively) than their double-negative counterparts (0.246±0.067 and 0.249±0.070 µm, respectively). Eyes with LF2>0.5 did not significantly differ in mean D and Dp from their counterparts, but eyes with LF2>0.7 did (Dp 0.47±0.91 vs 0.99±1.10, p=0.03; D 0.94±0.85 vs 1.42±1.14, p=0.03). LF2 reached highest concordance with Dp (86.9%) and D (76.2%) with a >0.7 cutoff, and conversely, the latter showed highest concordance with LF2 (89.3% and 86.4%, respectively) with a ≥2.0 cutoff.

 
Conclusions
 

Striving for high sensitivity for ectasia detection by a single method comes at the cost of reduced specificity. Concordance between ORA testing and Pentacam Scheimpflug tomography is acceptable, but there is the prospect of lowering the false positive rate by combining both technologies with modified diagnostic criteria.

 
Keywords: 479 cornea: clinical science • 574 keratoconus • 550 imaging/image analysis: clinical  
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