title: Automatic Cataract Hardness Classification Ex Vivo by Ultrasound Techniques.
abstract: To demonstrate the feasibility of a new methodology for cataract hardness characterization and automatic classification using ultrasound techniques, different cataract degrees were induced in 210 porcine lenses. A 25-MHz ultrasound transducer was used to obtain acoustical parameters (velocity and attenuation) and backscattering signals. B-Scan and parametric Nakagami images were constructed. Ninety-seven parameters were extracted and subjected to a Principal Component Analysis. Bayes, K-Nearest-Neighbours, Fisher Linear Discriminant and Support Vector Machine (SVM) classifiers were used to automatically classify the different cataract severities. Statistically significant increases with cataract formation were found for velocity, attenuation, mean brightness intensity of the B-Scan images and mean Nakagami m parameter (p < 0.01). The four classifiers showed a good performance for healthy versus cataractous lenses (F-measure ≥ 92.68%), while for initial versus severe cataracts the SVM classifier showed the higher performance (90.62%). The results showed that ultrasound techniques can be used for non-invasive cataract hardness characterization and automatic classification.
authors.affiliation: Department of Physics, University of Coimbra, PT-3030-290 Coimbra, Portugal; Department of Electrical and Computer Engineering, University of Coimbra, Coimbra, Portugal. Electronic address: miguel.caixinha@gmail.com.
authors.forename: Miguel
authors.initials: M
authors.lastname: Caixinha
authors.affiliation: Department of Physics, University of Coimbra, PT-3030-290 Coimbra, Portugal.
authors.forename: Mário
authors.initials: M
authors.lastname: Santos
authors.affiliation: Department of Physics, University of Coimbra, PT-3030-290 Coimbra, Portugal.
authors.forename: Jaime
authors.initials: J
authors.lastname: Santos
mesh_terms: D000818:Animals; D002386:Cataract / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003941:Diagnostic Techniques, Ophthalmological; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques; D005240:Feasibility Studies; D006244:Hardness; D006245:Hardness Tests; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D007908:Lens, Crystalline / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
keywords: Cataract; Classification; Phacoemulsification; SVM; Ultrasound