Analysis of Retinal Vascular Density using Optical Coherence Tomography Angiography, to Differentiate Healthy, Glaucoma Suspect and Glaucomatous Eyes

Bharath Kumar, K (2019) Analysis of Retinal Vascular Density using Optical Coherence Tomography Angiography, to Differentiate Healthy, Glaucoma Suspect and Glaucomatous Eyes. Masters thesis, Christian Medical College, Vellore.

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Abstract

OBJECTIVES: To study and compare vascular density in papillary retina using OCT Angiography in normals, Glaucoma suspects (Ocular hypertension), early POAG patients and its correlation with RNFL thickness and field changes. METHODS: All volunteers fulfilling eligibility criteria and willing to participate in the study, were recruited in three arms (Minimum sample size of 16 each) and underwent a full ophthalmic examination and investigations (Central corneal thickness, automated visual field testing (HFA 24-2 SITA, threshold test), optical coherence tomography (OCT) RNFL thickness (3.4 mm diameter circle around disc) and OCT angiography (3x3 mm scan) of optic disc, papillary and peri-papillary areas. Quantitative analysis of vessel density was performed using the publically available, open source, ImageJ software, after background subtraction of OCTA image. Data was tabulated and analyzed using STATA/IC 15.0 software. RESULTS: A significant relationship exists between vessel density and RNFL thinning, worsening Global indices on perimetry. Inferior RNFL thickness in O-HTN group showed statistically significant difference compared to normals (p = 0.020), which may be missed if RNFL thickness alone is seen. Papillary and peri–papillary area vessel densities had the best diagnostic accuracy to correctly differentiae normals, O-HTN and early POAG groups (AUC = 1.000). Even though a significant relationship exists between RNFL loss and decrease in vessel density, further longitudinal studies are needed to establish a temporal cause-effect relationship. CONCLUSIONS: Using the DRI-TRITON Plus swept source optical coherence tomography machine, we can acquire high resolution OCT scans which provide information about, not only the retinal nerve fiber layer thickness, but also about the vessel density in the retinal microcirculation in all the layers of the retina. Our study shows that there is a significant relationship between the vessel density and the structural changes in the retina in glaucoma, in the form of RNFL thinning and functional changes in glaucoma, in the form of worsening Global indices on automated perimetry. We found that the Inferior RNFL thickness in the Ocular hypertension group, even though within normal limits, for age, was at the lower end of normal, and that there was a statistically significant difference between the normals and suspects (O-HTN group), which may be missed if only RNFL thickness is seen in isolation. We also found that papillary area and peri–papillary area vessel densities had the best diagnostic ability and accuracy to correctly differentiae the normals, suspects (O-HTN) and diseased (early POAG) groups, which were in agreement with other previous studies. Even though a significant relationship exists between RNFL loss and decrease in vessel density, further longitudinal studies are needed to establish a temporal cause-effect relationship between the two entities.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Ocular Hypertension, Early Primary Open Angle Glaucoma, Optical coherence tomography, OCT, OCT Angiography, Vascular Density, Optic nerve head, Papillary area, Peri-papillary area.
Subjects: MEDICAL > Ophthalmology
Depositing User: Subramani R
Date Deposited: 01 Sep 2019 02:36
Last Modified: 01 Sep 2019 02:36
URI: http://repository-tnmgrmu.ac.in/id/eprint/11337

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