Progression in Glaucoma
Abstract: The treatment of glaucoma is focused on reducing the intraocular pressure to a level at which progression is impeded. A diagnosis of glaucoma is not considered certain until progression is confirmed, and thus detecting progression is a central aspect in both the diagnosing and the monitoring of glaucoma patients. Progression can be identified either through examination of either functional changes in the visual field or structural changes in the retinal nerve fibre layer in the optic disc or in the retina. Optic disc photography, and optical coherence tomography (OCT) that uses laser light, are two methods that are widely used to detect structural changes.The objectives of the present research were three-fold: (1) to assess how often a correct diagnosis was made during the few initial clinical visits, when no knowledge of progression was available; (2) to compare visual field examination and optic disc photography as methods to detect progression in glaucoma patients; (3) to evaluate the capacity of OCT to detect the rate of change in the retinal nerve fibre layer. For the first and second objectives, we studied glaucoma patients that had been included in the Early Manifest Glaucoma Trial, in which up to 20 years of regular prospective examinations were performed. To achieve the third objective, two different cohorts of healthy individuals and glaucoma patients were re-examined at a 10-year follow-up visit.Automated visual field examinations with strict criteria for defining glaucoma resulted in a correct diagnosis in 97% of patients after only two initial visits. Comparing visual fields and optic disc photographs among the glaucoma patients, the visual field examinations detected progression approximately four times as often. However, in eyes without glaucoma, progression was detected equally often by the two methods. The OCT method could not demonstrate a statistically significant difference in rate of change between healthy individuals and glaucoma patients. The automated OCT progression analysis, which is designed to assist the clinician in detecting glaucoma progression, gave excessively high rates of false positives.Guidelines recommend examinations of both functional and structural measures throughout the lifelong follow-up of glaucoma, a goal that is seldom achieved in reality. Inasmuch as health care resources are limited, the results presented in this thesis can aid in selecting the optimal method to monitor this large group of patients with different stages of glaucoma.
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