Identification and characterisation of ganglion cell loss in optic neuropathies

This thesis explores the identification of ganglion cell loss in optic neuropathies, and utilizes new technologies. Two commonly prevalent optic neuropathies have been studied – Glaucoma, which is common among the older population and Mutiple Sclerosis (MS) associated optic neuropathy, which is more prevalent in the younger population. The aim of the glaucoma study was to identify the combination of the tests that would identify very early loss of ganglion cells. Knowledge of this impact will then allow clinicians to identify patients with early glaucomatous damage and start treatment before evident visual field loss. The study revealed that Heidelberg retina tomograph (HRT) and Low contrast multifocal visual evoked potential (LLA mfVEP) were two sensitive tests in detecting patients with preperimetric and early glaucomatous defects. The aim of the MS study was to identify ganglion cell loss in patients with MS with or without previous history of Optic Neuritis (ON). The study also aimed to prove if the eye is a primary site of neurodegeneration in patients with multiple sclerosis. This could possibly shed some light in the pathological changes in the eye that occurs with MS related neurodegeneration. The results of the study indicated the presence of a trans neuronal degeneration, which could be retrograde (from optic radiation to retina) or anterograde (from retina to visual cortex). We also proved the absence of retrograde degeneration since the ERG changes were of similar magnitude in both ON and NON eyes of MS patients.