Authors (including presenting author) :
Wan KHN(1)(2), Leung CKS(2)(3)
Affiliation :
(1)Department of Ophthalmology, Tuen Mun Hospital (2)Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong (3)Hong Kong Eye Hospital
Introduction :
Glaucoma is an optic neuropathy characterized by progressive and irreversible degeneration of retinal ganglion cells (RGCs), resulting in specific patterns of visual field deficits. It is the leading cause of irreversible blindness in the world. Swept-source optical coherence tomography (OCT) is a new non-invasive imaging modality using a tunable laser source with a long wavelength to provide qualitative and quantitative information of both superficial and deep structures of the retina. Whereas OCT angiography (OCT-A) is a new imaging technique based on an extension to OCT to provide non-invasive visualization and assessment of retinal microcirculation. Early detection of glaucoma is of paramount importance for early treatment. Swept-source OCT and OCT-A could both provide further insights into early glaucomatous changes at the axonal/cellular and vascular level to enhance early disease detection.
Objectives :
Macula is a strategic location for detection of early vascular and structural events in glaucoma because it has highest density of RGC in the retina. We compared (1) the diagnostic performance for detection of glaucoma and (2) the structure-function association between inner macular vessel density and inner macular thickness using OCT and OCT-A.
Methodology :
This cross-sectional study included 115 patients with glaucoma and 35 healthy individuals for measurements of inner retinal thickness and retinal vessel density over the macula. Visual sensitivity corresponding to the macular region was expressed in unlogged 1/lambert for investigation of the structure-function associations using R2 analysis. Diagnostic performance was evaluated with area under the receiver operating characteristic curves (AUCs).
Result & Outcome :
Macular vessel density and thickness were 4.3% (95% CI, 2.4%-6.1%) and 21.1 μm (95% CI, 17.4-24.9 μm) smaller, respectively, in eyes with glaucoma compared with healthy eyes. The AUC of macular thickness for glaucoma detection was greater than that of macular vessel density (difference, 0.17; P = .03). At 90% specificity, the sensitivity of macular thicknesses for detection of glaucoma was greater than that of macular vessel densities (difference, 29.2%; P = .02). The strength of the structure-function association was stronger for macular thickness than macular vessel density in the linear (difference in R2 = 0.38; P < .001) and nonlinear (difference in R2 = 0.36; P < .001) regression models. OCT measurement of inner macular thickness shows a higher diagnostic performance to detect glaucoma and a stronger structure-function association than the OCT-A measurement of inner macular vessel density. OCT outperforms OCT-A in glaucoma evaluation.
