Percorrer por autor "Oliveira, Sara"
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- Early retinal changes in type 2 diabetes detected by texture-based OCT analysis: potential approach for subclinical diabetic retinopathy diagnosisPublication . Oliveira, Sara; Guimarães, Pedro; Roque-Rosado, Ângelo; Campos, Elisa Julião; Serranho, Pedro; Matafome, Paulo; Bernardes, Rui; Ambrósio, António FranciscoBackground: Diabetic retinopathy (DR) is often diagnosed many years after diabetes onset, highlighting the need for early diagnosis. The current study aimed to assess whether texture analysis of computed optical coherence tomography (OCT) retinal images can identify (very) early retinal changes. We previously reported retinal texture changes in a type 1 diabetes animal model. This study extends this approach to a type 2 diabetes model exhibiting subtler, more gradually developing retinal alterations to further explore its potential for detecting texture changes when DR-related retinal alterations are minor, strengthening its promising value. Methods: OCT scans and electroretinograms were acquired at baseline and 4, 8, and 12 weeks after initiating the diabetes induction protocol. Automated OCT segmentation, retinal thickness computation, and texture analysis were performed. Blood-retinal barrier permeability, glial reactivity, neuroinflammation, and nitrosative stress were assessed. Results: Retinal texture was affected in the inner plexiform layer and inner/outer photoreceptor segments. At weeks 8 and 12, autocorrelation, cluster prominence, correlation, homogeneity, information measure of correlation II, inverse difference moment normalised, inverse difference normalised, and sum average texture metrics significantly increased/decreased. Importantly, seven of these metrics were also altered in our previous study with type 1 diabetic animals. Type 2 diabetic retinas presented subtle thinning and impaired function, along with a slight reduction in tight junction proteins immunoreactivity, without affecting the blood-retinal barrier. Conclusions: The findings from this study indicate that texture analysis can identify subtle retinal changes during early, clinically silent stages of disease, when biological alterations remain minimal. This highlights its potential utility for the early diagnosis of diabetic retinopathy, though further clinical validation is needed.
- Retinal OCT-derived texture features as potential biomarkers for early diagnosis and progression of Diabetic RetinopathyPublication . Oliveira, Sara; Guimarães, Pedro; Campos, Elisa Julião; Fernandes, Rosa; Martins, João; Castelo-Branco, Miguel; Serranho, Pedro; Matafome, Paulo; Bernardes, Rui; Ambrósio, António FranciscoPURPOSE. Diabetic retinopathy (DR) is usually diagnosed many years after diabetes onset. Indeed, an early diagnosis of DR remains a notable challenge, and, thus, developing novel approaches for earlier disease detection is of utmost importance. We aim to explore the potential of texture analysis of optical coherence tomography (OCT) retinal images in detecting retinal changes in streptozotocin (STZ)-induced diabetic animals at “silent” disease stages when early retinal molecular and cellular changes that cannot be clinically detectable are already occurring. METHODS. Volume OCT scans and electroretinograms were acquired before and 1, 2, and 4 weeks after diabetes induction. Automated OCT image segmentation was performed, followed by retinal thickness and texture analysis. Blood-retinal barrier breakdown, glial reactivity, and neuroinflammation were also assessed. RESULTS. Type 1 diabetes induced significant early changes in several texture metrics. At week 4 of diabetes, autocorrelation, correlation, homogeneity, information measure of correlation II (IMCII), inverse difference moment normalized (IDN), inverse difference normalized (INN), and sum average texture metrics decreased in all retinal layers. Similar effects were observed for correlation, homogeneity, IMCII, IDN, and INN at week 2. Moreover, the values of those seven-texture metrics described above decreased throughout the disease progression. In diabetic animals, subtle retinal thinning and impaired retinal function were detected, as well as an increase in the number of Iba1-positive cells (microglia/macrophages) and a subtle decrease in the tight junction protein immunoreactivity, which did not induce any physiologically relevant effect on the blood-retinal barrier. CONCLUSIONS. The effects of diabetes on the retina can be spotted through retinal texture analysis in the early stages of the disease. Changes in retinal texture are concomitant with biological retinal changes, thus unlocking the potential of texture analysis for the early diagnosis of DR. However, this requires to be proven in clinical studies.