Noninvasive Evaluation of Retinal Leakage Using Optical Coherence Tomography

Abstract

Purpose: To demonstrate the association between changes in the blood-retinal barrier (BRB) identified by fluorescein leakage and those in the optical properties of the human retina determined by optical coherence tomography (OCT) and show how these changes can be quantified and their location identified within the retina. Methods: Two imaging techniques were applied: the retinal leakage analyzer, to map BRB function into intact or disrupted regions, and OCT, to measure refractive index changes along the light path within the human ocular fundus. Results: A total of 140 comparisons were made, 77 between areas of regions receiving the same classification (intact or disrupted BRB) and 63 between areas of regions receiving distinct classifications, from 4 pathological cases: 2 eyes with nonproliferative diabetic retinopathy and 2 eyes with wet age-related macular degeneration. In all cases, the distribution of OCT data between regions of intact and regions of disrupted BRB, identified by the retinal leakage analyzer, was quantified and was statistically significantly different (p < 0.001). In addition, it was found that the differences could be localized in the retina to specific structural sequences. Conclusions: Using a novel method to analyze OCT data, we showed that it may be possible to quantify differences in the extracellular compartment in eyes with retinal disease and alterations of the BRB. Based on quantitative techniques, our findings demonstrate the presence of indirect information on the BRB status within noninvasive OCT data.

A Splitting Algorithm for Medical Image Denoising

“…All these pathologies can be diagnosed more conclusively with the help OCT (Serranho, Morgado, Bernardes 2012), (Bouma, Tearney 2002). In fact, previous studies have established a link between changes in the blood-retina barrier and in optical properties of the retina (Bernardes, Santos, Serranho, Lobo, Cunha-Vaz 2011) which can be identified by this exam.…”

Optical Coherence Tomography ? Automatic Retina Classification Through Support Vector Machines

“…Following the authors initial proof of concept that OCT data embeds information on the BRB, 11,14 the authors went a step further demonstrating the possibility to discriminate between healthy and diseased eyes (diabetic retinopathy eyes) resorting to an automatic classification procedure widely used -the SVM classification process. 16,17 Since the classification is based on the statistics of the OCT data only, the fact the system is able to correctly classify eyes in the proper group in over 64 % of the cases (see Table 4) clearly suggests the presence of this information embedded within the OCT data.…”

“…In brief, it was demonstrated that differences in the histograms of OCT data were significantly distinct from regions of intact to regions of disrupted BRB. 11,14 Moreover, it demonstrated the association of the differences found with the retinal vascular network through the depth discrimination within the retinal tissue. This discrimination demonstrated that the differences found were significantly different within the top 1/3 of the human retina, the location of the majority of the retinal vascular network, thus establishing a direct association between the differences found and the inner BRB.…”

Advances in Imaging in Age-Related Macular Degeneration

“…In more recent years, efforts have also been made to obtain direct measurements of fluorescein leakage. Examples of this approach include ''topographic angiography'' (TAG) and the ''retinal leakage analyzer'' (RLA) [23,24]. In both cases, a confocal SLO is used to obtain a stack of 32 images at different focal planes between the vitreous and the choroid.…”