研究目的
To study the microvascular density of the macular and optic nerve head in healthy and glaucoma subjects using optical coherence tomography angiography.
研究成果
Microvascular density is reduced in glaucoma patients compared to healthy controls in both optic disc and macula regions, with high diagnostic accuracy for differentiating between them using vessel density measurements. Optical coherence tomography angiography shows promise as a diagnostic tool and potential marker for glaucoma progression, though longitudinal studies are needed to establish causality and the effects of disease control.
研究不足
Possible confounding from age difference between groups (glaucoma group slightly older), media opacity (cataracts) affecting image quality and recruitment, use of both eyes per subject limiting multivariate analysis, single operator for scans without intraobserver variability assessment, cross-sectional design preventing cause-effect determination, and inability to assess impact of factors like age, media opacity, intraocular pressure, and axial length on vessel density.
1：Experimental Design and Method Selection:
A cross-sectional cohort study was conducted using optical coherence tomography angiography (OCTA) to image the optic nerve head and macula. The AngioVue Enhanced Microvascular Imaging System was employed with the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm for motion-contrast blood flow imaging. En face segment images were analyzed in layers for microvascular density quantification using in-house developed software based on automated pixel counting and the Scale and Curvature Invariant Ridge Detector (SCIRD) for vessel detection.
2：Sample Selection and Data Sources:
Subjects were enrolled from the ophthalmology clinic of Tan Tock Seng Hospital, including 24 glaucoma patients (32 eyes) and 29 age-matched healthy controls (58 eyes). Inclusion criteria for glaucoma: confirmed by abnormal standard automated perimetry and glaucomatous disc changes; for controls: normal optic disc, retina, visual acuity, and intraocular pressure. Exclusion criteria: ocular pathologies, systemic diseases affecting vision, pregnancy, age under
3：List of Experimental Equipment and Materials:
AngioVue Enhanced Microvascular Imaging System (Optovue, Fremont, CA), Humphrey visual field Analyzer Swedish Interactive Threshold Algorithm standard 24-2 (Carl Zeiss Meditec, Dublin, CA), Goldmann applanation tonometer, slit-lamp, and in-house developed software for vessel density calculation.
4：Experimental Procedures and Operational Workflow:
Subjects underwent ophthalmic assessment including visual acuity, slit-lamp exam, intraocular pressure measurement, and visual field testing. OCTA scans were performed with the AngioVue system using 3x3 mm cubes centered on the optic nerve head and fovea. Images were reviewed for artifacts and poor signal strength (signal strength index <40 discarded). Segmentation into layers (optic disc: superficial nerve head, vitreoretinal interface, radial peripapillary capillaries, choroid; macula: superficial retina, deep retina, outer retina, choriocapillaris) and subdivision into quadrants was done automatically by the system. Vessel density was calculated as the percentage of vessel pixels in each region.
5：Data Analysis Methods:
Statistical analysis used IBM SPSS Statistics (version 22) with independent T-tests and Benjamini-Hochberg correction for multiple comparisons. Diagnostic accuracy was evaluated using area under the receiver operating characteristic (AUROC) curves.
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