| dc.description.abstract | Glaucoma is characterized by degeneration of the retinal nerve fiber layer (RNFL), which can be assessed by thickness measurement on optical coherence tomography (OCT) B-scans. However, detecting early-stage glaucoma remains a challenge. Due to biological variations in the eyes of healthy individuals, there exists an inherent overlap between the thickness of early-stage glaucomatous RNFL and healthy RNFL. More importantly, glaucoma suspect patients represent a large portion of glaucoma patients seen at the clinics; however, current diagnostic tools lack the sensitivity in detecting early-stage changes in the suspect population. Therefore, there is a need for a new diagnostic biomarker to provide better indication of disease development in such population. In this thesis study, I aim to investigate the effectiveness of the attenuation coefficient (AC) and AC-derived parameters for detecting early-stage changes glaucomatous eye. Here, I present a comparison study for two methods of AC extraction from the retinal nerve fiber layer of clinical optical coherence tomography (OCT) B-scans collected from four study groups. The groups include healthy individuals, glaucoma suspect patients, mild and severe stage glaucoma patients. The results show comparable performances of the two methods and reveal a decreasing trend in the calculated AC as disease stage progress. I also introduce novel depth-dependent AC parameters calculated from pixel-wise AC measurements. The new parameters are shown to further differentiate the early-stage population from the healthy group. Biological reasonings for the observed trends may relate to the changes in axon density and capillary density as a function of depth and disease severity. | |
