Introduction: The eye offers potential for the diagnosis of Alzheimer’s disease (AD) with retinal imaging techniques being explored to quantify amyloid accumulation and aspects of neurodegeneration. To assess these changes, this proof-of-concept study combined hyperspectral imaging and optical coherence tomography to build a classification model to differentiate between AD patients and controls. Methods: In a memory clinic setting, patients with a diagnosis of clinically probable AD (n = 10) or biomarker-proven AD (n = 7) and controls (n = 22) underwent non-invasive retinal imaging with an easy-to-use hyperspectral snapshot camera that collects information from 16 spectral bands (460–620 nm, 10-nm bandwidth) in one capture. The individuals were also imaged using optical coherence tomography for assessing retinal nerve fiber layer thickness (RNFL). Dedicated image preprocessing analysis was followed by machine learning to discriminate between both groups. Results: Hyperspectral data and retinal nerve fiber layer thickness data were used in a linear discriminant classification model to discriminate between AD patients and controls. Nested leave-one-out cross-validation resulted in a fair accuracy, providing an area under the receiver operating characteristic curve of 0.74 (95% confidence interval [0.60–0.89]). Inner loop results showed that the inclusion of the RNFL features resulted in an improvement of the area under the receiver operating characteristic curve: for the most informative region assessed, the average area under the receiver operating characteristic curve was 0.70 (95% confidence interval [0.55, 0.86]) and 0.79 (95% confidence interval [0.65, 0.93]), respectively. The robust statistics used in this study reduces the risk of overfitting and partly compensates for the limited sample size. Conclusions: This study in a memory-clinic-based cohort supports the potential of hyperspectral imaging and suggests an added value of combining retinal imaging modalities. Standardization and longitudinal data on fully amyloid-phenotyped cohorts are required to elucidate the relationship between retinal structure and cognitive function and to evaluate the robustness of the classification model.
1 February 2014 in Investigative Ophthalmology & Visual Science
Purpose.: To determine whether ROCK inhibition for the treatment of glaucoma can be improved by using novel, locally acting Rho kinase (ROCK) inhibitors, such as AMA0076, that lower IOP without inducing hyperemia. Methods.: On-target potency of AMA0076 was compared with other ROCK inhibitors (Y-27632 and Y-39983) and conversion of AMA0076 into its functionally inactive metabolite was evaluated in rabbit eye tissues. Human trabecular meshwork (HTM) cell morphology, actin filaments, and focal adhesion were studied in vitro after exposure to AMA0076. The effect of AMA0076 on IOP was investigated in normotensive rabbits and a new, acute hypertensive rabbit model. Intraocular pressure lowering efficacy of AMA0076 was compared with pharmacologic treatments. Hyperemia after single topical dosing of AMA0076 and Y-39983 was scored. Results.: AMA0076 and Y-39983 showed similar on-target potency. AMA0076 was most stable in aqueous humor and converted into its metabolite in other eye tissues. Exposure of HTM cells to AMA0076 led to significant and reversible changes in cell shape and a decrease in actin stress fibers and focal adhesions. Both AMA0076 and Y-39983 provided an equivalent IOP control. Compared with latanoprost and bimatoprost, AMA0076 was more potent in preventing the IOP elevation in the acute hypertensive rabbit model. The degree of hyperemia was significantly lower in rabbits treated with AMA0076 then with Y-39983. Conclusions.: AMA0076 is a locally acting ROCK inhibitor that is able to induce altered cellular behavior of HTM cells. Administration of AMA0076 effectively reduces IOP in ocular normotensive and acute hypertensive rabbits without causing distinct hyperemia.