Fluid Mechanics in Ophthalmology: Age-Related Macular Degeneration from Pathogenesis to Treatment

The most common pathologies affecting the elderly are Age-related Macular Degeneration (AMD), cataracts, glaucoma, diabetic retinopathy, and presbyopia. AMD, in its wet form, primarily involves the macula and is treated with anti-VEGF intravitreal injections. In wet AMD, fluid leakage may result in a specific retina detachment at the fovea, the central part of the macula. Indeed, fluid leakage and abnormal blood vessel growth can exert pressure on the retina, leading to retinal detachment. Retinal detachment and certain severe cases of diabetic retinopathy may necessitate vitrectomy, a surgical procedure involving the removal of the vitreous humour and its substitution with either a saline solution or silicone oil. Maintaining control over intraocular pressure is crucial during vitrectomy to mitigate potential complications. AMD significantly impacts vision, causing permanent central vision loss. This affects the ability to see details clearly and potentially distorted or wavy lines. If left untreated, especially in later stages, AMD can progress to legal. This PhD thesis discusses the pathology's progression and its treatments, focusing on the physio-pathological aspects of AMD. Specifically, it examines the factors influencing fluid circulation in the retina and anti-VEGF distribution. Additionally, it addresses certain clinical issues through an experimental approach involving in vitro pressure and vibration measurements using various vitrectomy devices. Specifically, this dissertation presents a mathematical model of the onset of exudative macular oedema. This research seeks to understand the circulation patterns within the retina, aiming to explain the formation of oedema in a specific zone called the fovea, which is not the location of exudation. Moreover, a theoretical model of drug distribution following intravitreal injection is presented. Anti-VEGF injections represent the gold standard for treating wet AMD. This research aims to evaluate the extent to which the injected antibodies are transported to the target region, which is the retina. Furthermore, this thesis focuses on experimental activities related to pressure measurements in a real-scale 3D printed model of a vitreous chamber to replicate vitrectomy surgery and on vibration tests on vitreous cutters operating at various cutting frequencies.