School of Optometry and Vision Science, Faculty of Life Sciences
Abstract
Glaucoma is a leading cause of irreversible vision loss globally, and demands
early and accurate diagnosis. OCT has become a key investigative technique
in glaucoma, and, although it provides invaluable clinical support, detection of
early glaucoma remains imperfect. Recent OCT developments enabled direct
assessment of retinal nerve fibre bundle (RNFB) reflectance in en face OCT
images. The technique has considerable potential in the assessment of
glaucoma, yet it has limited clinical usability due to an incomplete
understanding of RNFB features in healthy and glaucoma eyes and the lack
of accepted methods to identify reflectance defects. This thesis aimed to better
understand characteristics of RNFB reflectance in en face OCT imaging and
to develop objective methods to extract defects in this domain.
Structural and functional measures of glaucoma changes were collected in
eyes with established glaucoma and age-similar controls. Results showed that
the healthy configuration of RNFB varies across the retina and between
different eyes. We developed a method for automated and objective
examination of reflectivity changes in en face images. This method considers
individual anatomy and varying RNFB configuration, and found more
abnormalities than previous approaches. Measures of en face reflectance and
conventional retinal nerve fibre layer thickness were strongly related. The
agreement between changes of reflectance and visual function was
moderate-to-good, and both testing domains presented concordant abnormalities
in all tested eyes.
Following further minimisation of artefacts in en face images, direct use of
reflectance analysis or its combination with perimetry appear viable and with
significant potential for clinical examination of glaucoma
