The Complexity of Diagnosing and Monitoring Glaucoma

Glaucoma is a heterogeneous group of progressive optic neuropathies characterised by an accelerated degeneration of retinal ganglion cells (RGCs) and their axons, resulting in a typical appearance of the optic nerve head and a matching pattern of irreversible visual field loss. Worldwide, approximately 12% of all blindness is due to glaucoma, which makes it the second leading cause of blindness. To date, there is still no technique that measures the exact nature of the disease (the death of the RGCs and their axons). All techniques developed in the past decades indirectly measure the functional and structural loss. In measuring glaucoma, the function of the eye is determined by measuring the visual field by perimetry. Several types of perimetry have been developed to measure the functional glaucomatous loss. The structural loss due to glaucoma is determined by measuring the optic nerve head (ONH), which changes due to loss of RGCs and its axons, leading to a typical cupping of the ONH and the subsequent loss or thinning of the retinal nerve fiber layer. These structural changes are currently measured by several imaging techniques, such as optical coherence tomography (OCT), confocal scanning laser ophthalmoscopy (CSLO) and scanning laser polarimetry (SLP).
The objective of the research presented in this thesis was to evaluate various techniques used in daily glaucoma practice to diagnose and monitor glaucoma. This has been established by incorporating several analyses on conversion from ocular hypertension to glaucoma, using measures of function and structure. Furthermore, we also analysed (progressing) glaucomatous eyes by the techniques used most frequently in daily practice and by the newest clinically used technique, i.e. optical coherence tomography.