Hidalgo-Aguire, Maribel
(2018).
Investigation of pulsatile retinal
deformation as new biomechanical
descriptor of the human ocular dynamics
for glaucoma prognosis.
Thèse.
Québec, Université du Québec, Institut national de la recherche scientifique, Doctorat en sciences de l'énergie et des matériaux, 176 p.
Résumé
Glaucoma is the second leading cause of blindness worldwide. The facts
that glaucoma does not present any symptoms until major visual loss has
occurred and that the primary causes of this neuropathy remain unknown
make it challenging for both, diagnosis and treatment. While elevated
intraocular pressure (IOP) remains the primary risk factor, other parameters
such as low ocular perfusion pressure, ocular blood flow and the
elasticity of the sclera and lamina cribrosa have been identified in the last
years as additional factors potentially influencing the risk, prevalence and
progression of the glaucomatous neuropathy.
Theoretically, an individual’s susceptibility to IOP is in part determined
by the eye geometry and tissue anatomy, therefore, it seems natural to
consider biomechanics as framework for explaining how IOP-related stress
and strain influence the physiology and pathophysiology of the connective,
neural and vascular tissue, causing the changes on the structural and
functional integrity of the optic nerve observed in glaucoma. The key
challenge is then to understand how ocular biomechanics, in combination
with the aforementioned risk factors, are transduced into tissue damage.
It has been demonstrated that glaucoma is directly related with blood
flow deficiencies in the retinal and choroidal circulation. The choroid has
the highest blood flow per gram tissue of any organ in the human body
and this flow is 80 % pulsatile. This pulsatility has been hypothesized to
drive the retina forward while expanding the sclera, leading to a pulsatile
deformation of the axons traveling from the retina and through the lamina
cribrosa to the brain. If we consider that the mechanical properties of the
tissues are also altered during the progression of the disease, then is very
likely that such deformation may change. Within this framework, the present work is centered on the study and characterization
of the peripapillary retinal tissue deformation due to choroidal
vascular pulsatility and its possible implication in axonal damage and loss
of the retinal nerve fiber layer in glaucoma. The general strategy designed
to perform such investigation is to use video rate optical coherence tomography
images of the optic nerve head combined with fully automated
image analysis algorithms specially developed to measure and determine
retinal deformation. A cross-sectional study was then carried out at the
ophthalmology clinic of the Maisonneuve-Rosemont Hospital to evaluate
peripapillary retinal deformation on patients that cover the most representative
part of the glaucoma spectrum.
The obtained results show that healthy eyes have significantly larger deformation
of the peripapillary retina compared with the glaucoma spectrum.
The measured deformation correlates differently with the principal risk
factors of the glaucomatous neuropathy depending on diagnosis. Reduced
retinal displacement proved to be related to glaucoma progression predictors
showing that the biomechanical properties of the eye are altered even
when there is no evident changes in the optic nerve head structure.
Due to the versatility of the segmentation algorithm, it was possible to
carry out a preliminary study to investigate retinal deformation around
the macula using images previously acquired from a different clinic study.
In this case, perifoveal retinal deformation in healthy eyes resulted to be
significantly larger than in early glaucoma. Furthermore, ocular rigidity
as well as changes in ocular volume were correlated with perifoveal retinal
displacement in healthy eyes, which confirms that the observed deformation
is driven by choroidal pulsatility.
All these results suggest that the amount of retinal deformation should be
further investigated since it could be potentially used as a new biomechanical
descriptor of the eye for early diagnosis and assessment of glaucoma
progression.
Type de document: |
Thèse
Thèse
|
Directeur de mémoire/thèse: |
Costantino, Santiago |
Co-directeurs de mémoire/thèse: |
Lesk, Mark R.; Ozaki, Tsuneyuki |
Mots-clés libres: |
optic nerve head; glaucoma; image processing; optical
coherence tomography; ocular biomechanics; ocular dynamics; retinal
deformation |
Centre: |
Centre Énergie Matériaux Télécommunications |
Date de dépôt: |
19 oct. 2018 15:36 |
Dernière modification: |
19 oct. 2018 15:36 |
URI: |
http://espace.inrs.ca/id/eprint/7640 |
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