Browsing by Author "Soundararajan, Srinath"

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    Choroidal Structural Analysis in Alzheimer's Disease, Mild Cognitive Impairment, and Cognitively Healthy Controls.
    (Am J Ophthalmol, 2020-10-08) Robbins, Cason B; Grewal, Dilraj S; Thompson, Atalie C; Powers, James H; Soundararajan, Srinath; Koo, Hui Yan; Yoon, Stephen P; Polascik, Bryce W; Liu, Andy; Agrawal, Rupesh; Fekrat, Sharon
    PURPOSE: To assess choroidal structural parameters in symptomatic Alzheimer's disease (AD), mild cognitive impairment (MCI), and cognitively healthy controls. DESIGN: Prospective cross-sectional study. METHODS: Setting: Outpatient neurological disorders clinic. STUDY POPULATION: One hundred and twelve eyes of 67 individuals with AD, 143 eyes of 74 individuals with MCI, and 248 eyes of 137 controls. Individuals with diabetes, glaucoma, or retinal pathology were excluded. OBSERVATION PROCEDURE: High-definition EDI foveal scans were obtained using Zeiss Cirrus HD-5000 AngioPlex (Carl Zeiss Meditec, Dublin, CA). Subfoveal choroidal thickness (SFCT) was measured by two masked graders with a third adjudicator. Total choroidal area (TCA), luminal area (LA), and choroidal vascularity index (CVI) were calculated after image binarization. MAIN OUTCOME MEASURES: Association of choroidal parameters with AD, MCI, or controls using generalized estimating equations, adjusted for age and sex. RESULTS: After adjustment for age, sex, and visual acuity, TCA was significantly greater in AD (ß 2.73, p = 0.001) and MCI (ß 4.38, p < 0.001) compared to controls, LA was significantly greater in AD (ß 1.68, p = 0.001) and MCI (ß 2.69, p < 0.001) compared to controls, and CVI was significantly lower in MCI (ß -0.58, p = 0.002) compared to controls. SFCT was similar among AD, MCI, and controls on multivariable analysis (p > 0.05). CONCLUSIONS: TCA, LA, and CVI may differ between individuals with AD, MCI, and healthy cognition, whereas SFCT may not differ between these groups. TCA, LA, and CVI deserve further study in individuals along the Alzheimer's continuum.
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    Convolutional neural network to identify symptomatic Alzheimer's disease using multimodal retinal imaging.
    (The British journal of ophthalmology, 2020-11-26) Wisely, C Ellis; Wang, Dong; Henao, Ricardo; Grewal, Dilraj S; Thompson, Atalie C; Robbins, Cason B; Yoon, Stephen P; Soundararajan, Srinath; Polascik, Bryce W; Burke, James R; Liu, Andy; Carin, Lawrence; Fekrat, Sharon
    BACKGROUND/AIMS:To develop a convolutional neural network (CNN) to detect symptomatic Alzheimer's disease (AD) using a combination of multimodal retinal images and patient data. METHODS:Colour maps of ganglion cell-inner plexiform layer (GC-IPL) thickness, superficial capillary plexus (SCP) optical coherence tomography angiography (OCTA) images, and ultra-widefield (UWF) colour and fundus autofluorescence (FAF) scanning laser ophthalmoscopy images were captured in individuals with AD or healthy cognition. A CNN to predict AD diagnosis was developed using multimodal retinal images, OCT and OCTA quantitative data, and patient data. RESULTS:284 eyes of 159 subjects (222 eyes from 123 cognitively healthy subjects and 62 eyes from 36 subjects with AD) were used to develop the model. Area under the receiving operating characteristic curve (AUC) values for predicted probability of AD for the independent test set varied by input used: UWF colour AUC 0.450 (95% CI 0.282, 0.592), OCTA SCP 0.582 (95% CI 0.440, 0.724), UWF FAF 0.618 (95% CI 0.462, 0.773), GC-IPL maps 0.809 (95% CI 0.700, 0.919). A model incorporating all images, quantitative data and patient data (AUC 0.836 (CI 0.729, 0.943)) performed similarly to models only incorporating all images (AUC 0.829 (95% CI 0.719, 0.939)). GC-IPL maps, quantitative data and patient data AUC 0.841 (95% CI 0.739, 0.943). CONCLUSION:Our CNN used multimodal retinal images to successfully predict diagnosis of symptomatic AD in an independent test set. GC-IPL maps were the most useful single inputs for prediction. Models including only images performed similarly to models also including quantitative data and patient data.
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    Intrasession Repeatability of OCT Angiography Parameters in Neurodegenerative Disease.
    (Ophthalmology science, 2023-06) Akrobetu, Dennis Y; Robbins, Cason B; Ma, Justin P; Soundararajan, Srinath; Quist, Michael S; Stinnett, Sandra S; Moore, Kathryn PL; Johnson, Kim G; Liu, Andy J; Grewal, Dilraj S; Fekrat, Sharon

    Purpose

    To assess the intrasession repeatability of macular OCT angiography (OCTA) parameters in Alzheimer's disease (AD), mild cognitive impairment (MCI), Parkinson's disease (PD), and normal cognition (NC).

    Design

    Cross sectional study.

    Subjects

    Patients with a clinical diagnosis of AD, PD, MCI, or NC were imaged. Images with poor quality and of those with diabetes mellitus, glaucoma, or vitreoretinal disease were excluded from analysis.

    Methods intervention or testing

    All participants were imaged using the Zeiss Cirrus HD-5000 with AngioPlex (Carl Zeiss Meditec, Software Version 11.0.0.29946) and repeat OCTA images were obtained for both eyes. Perfusion density (PFD), vessel density (VD), and Foveal avascular zone (FAZ) area were measured from 3 × 3 mm and 6 × 6 mm OCTA images centered on the fovea using an ETDRS grid overlay.

    Main outcome measures

    Intraclass correlation coefficients were used to quantify repeatability of PFD, VD, and FAZ area measurements obtained from imaging.

    Results

    3 × 3 mm scans of 22 AD, 40 MCI, 21 PD, and 26 NC participants and 6 × 6 mm scans of 29 AD, 44 MCI, 29 PD, and 30 NC participants were analyzed. Repeatability values ranged from 0.64 (0.49-0.82) for 6 × 6 mm PFD in AD participants to 0.87 (0.67-0.92) for 3 × 3 mm PFD in AD participants. No significant differences were observed in repeatability between NC participants and those with neurodegenerative disease.

    Conclusions

    Overall, similar OCTA repeatability was observed between NC participants and those with neurodegeneration. Regardless of diagnostic group, macular OCTA metrics demonstrated moderate to good repeatability.

    Financial disclosures

    The authors have no proprietary or commercial interest in any materials discussed in this article.
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    Retinal and Choroidal Changes in Men Compared with Women with Alzheimer's Disease: A Case-Control Study.
    (Ophthalmology science, 2022-03) Mirzania, Delaram; Thompson, Atalie C; Robbins, Cason B; Soundararajan, Srinath; Lee, Jia Min; Agrawal, Rupesh; Liu, Andy J; Johnson, Kim G; Grewal, Dilraj S; Fekrat, Sharon

    Purpose

    To evaluate differences in the retinal microvasculature and structure and choroidal structure among men and women with Alzheimer's disease (AD) compared with age-matched cognitively normal male and female controls.

    Design

    Case-control study of participants ≥ 50 years of age.

    Participants

    A total of 202 eyes of 139 subjects (101 cases and 101 controls).

    Methods

    All participants and controls underwent OCT and OCT angiography (OCTA), and parameters of subjects with AD were compared with those of cognitively normal controls.

    Main outcome measures

    The foveal avascular zone (FAZ) area, vessel density (VD), and perfusion density (PD) in the superficial capillary plexus within the 3- and 6-mm circle and ring using Early Treatment Diabetic Retinopathy Study (ETDRS) grid overlay on OCTA; central subfield thickness (CST), retinal nerve fiber layer (RNFL) thickness, ganglion cell-inner plexiform layer (GCIPL) thickness, and choroidal vascularity index (CVI) on OCT.

    Results

    No significant sex differences in VD or PD were found in the AD or control cohorts; however, there were greater differences in VD and PD among AD female participants than AD male participants compared with their respective controls. The CST and FAZ area were not different between male and female AD participants. Among controls, men had a thicker CST (P < 0.001) and smaller FAZ area (P = 0.003) compared with women. The RNFL thickness, GCIPL thickness, and CVI were similar among male and female AD participants and controls.

    Conclusions

    There may be a loss of the physiologic sex-related differences in retinal structure and microvasculature in those with AD compared with controls. Further studies are needed to elucidate the pathophysiological basis for these findings.