Abstract
Background: The Sapphire II platform is a clinical diagnostic device intended for aiding clinical evaluation and measurement of beta-amyloid aggregation in anatomically defined regions of the anterior segment of the eye. It detects a specific fluorescent signature emission of ligand-marked beta amyloid complex in the supranuclear region of the human lens. The current study results are Sapphire II scan to be used to classify patients as normal, MCI and mild Alzheimer’s disease and the utility of Sapphire II screening compared to b-amyloid PET scans in MCI and Mild AD subjects. Method: A naïve Bayes classifier using a base model with the three most theoretically relevant parameters (τ1, τ2, φ). Sensitivity and specificity is assessed comparing the normal group to the collective MCI/Mild AD group. 48 participants; 28 MCI, 16 Mild AD patients and 4 Normal Control subjects were studied. Results: The Sapphire II naïve Bayes classifier with cross validation had sensitivity of 96%, specificity of 75%, and overall accuracy of 92%. Results based on 4 healthy controls only, with one of the control subjects tested positive in Sapphire II; additional testing on 10 healthy controls is in progress. Conclusion: Sapphire II offers a non-invasive, safe, easy to use, community based inexpensive method for accurately classifying individuals as normal, MCI or mild AD dementia on the basis of the beta amyloid in the lens of the eye. Sapphire II may offer a practical alternative to PET amyloid scans for biomarker confirmed AD diagnosis. Evaluation of individual PET scans and cognitive testing suggests that Sapphire II is more sensitive than PET.