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Vishal Jhanji, Tommy Chan, Marco Yu; Comparison between the diagnostic ability of corneal Tomography and novel biomechanical parameters in keratoconus. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2385. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Early and accurate diagnosis of keratoconus is of paramount importance for effective management of these cases. Corneal tomography as well as biomechanical evaluation are being increasingly employed for this purpose. This study compared the diagnostic ability of tomographic and novel biomechanical parameters in cases with keratoconus
Forty-two eyes of 42 participants were included (21 normal, 21 keratoconus). Corneal tomographic parameters were measured using Scheimpflug imaging (Pentacam, Oculus, Wetzlar, Germany). Biomechanical parameters were obtained from a Scheimpflug camera (Corvis, Oculus, Wetzlar, Germany). The area under receiver operating curve (AUC) and partial AUC for specificity ≥ 80% for each parameter was calculated to assess the discrimination ability and compared between devices. Correlation analysis was performed between parameters obtained from both devices. A p-value < 0.05 was considered statistically significant. In addition, deformation amplitude (DA) ratio 1 and 2, a ratio between deformation amplitude at apex and at 1mm and 2 mm from the centre of the corneal apex respectively, was proposed and validated on Corvis.
Corneal parameters were selected for comparison based on their diagnostic performance. Belin/Ambrosio Enhanced Ectasia Display (BAD) showed the highest AUC and partial AUC followed by Ambrosio’s relational thickness maximum (ARTmax) with AUC ≥ 0.95 and partial AUC ≥ 0.18. DA ratio 1 and 2 also demonstrated the highest AUC and partial AUC amongst other Corvis parameters. There was no significant difference for AUC and partial AUC of BAD and ARTmax compared to those of DA Ratio 1 and 2 (p>0.186). Significant correlation was found between BAD and DA Ratio 1 and 2 (p<0.003) as well as ARTmax and DA Ratio 1 and 2 (p<0.002) for eyes with keratoconus.
Novel biomechanical parameters were able to provide discriminative ability between normal and keratoconic eyes comparable to tomographic analysis using Scheimpflug imaging. Corneal biomechanics may have the potential to effectively diagnose keratoconus.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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