Visual Impairment and Vision-Related Quality of Life in Glaucoma
Abstract: This thesis addresses the impact of glaucoma on the patients’ vision from both a measurement based and a functionally based perspective. The risk of visual disability is probably the most important question for a newly diagnosed glaucoma patient and maintaining vision-related quality of life (VRQOL) has become the ultimate goal of glaucoma treatment. The objectives of the present thesis were to determine the lifetime risk and duration of glaucoma blindness in a large retrospective study on patients with glaucoma followed until death (Paper I); to investigate factors associated with the lifetime risk of glaucoma blindness (Paper II); to evaluate whether threat to fixation (TTF) at diagnosis increases the risk of glaucoma blindness or central vision loss (Paper III); and to analyse the relationship between visual function and VRQOL measured by the National Eye Institute Visual functioning Questionnaire 25 (NEI VFQ-25) in glaucoma patients from a prospective study after 20 years of follow-up (Paper IV). One out of six glaucoma patients was bilaterally blind at the last visit and on average 86 years when the best eye became blind. Median time with bilateral blindness was two years. These results, with the fact of an increasing life expectancy in mind, suggest that the burden of glaucoma related visual impairment might increase in the future in northern Europe. The risk of visual impairment was associated with a more advanced visual field (VF) defect and a higher intraocular pressure at diagnosis as well as an older age at death. Our findings make it particularly important to include an assessment of each patient’s general health into account when determining treatment and disease management. TTF at diagnosis was not an independent risk factor for glaucoma blindness or central vision loss. Instead the calculation of the risk of visual impairment could be based solely on the stage of VF loss. Patients with visual impairment in one or both eyes reported lower VRQOL than patients without such impairment. VRQOL was significantly worse in patients with a remaining better eye VF below 50% compared to patients with a less advanced defect. This result support that the widely used, though arbitrary, threshold of a visual field of 50% in the better eye indeed is correlated to the patients subjective VRQOL. However, the NEI VFQ-25 was not optimal targeted to our study population, which made it impossible to detect possible differences in VRQOL in patients with mild glaucoma. Future modifications of the NEI VFQ-25 could improve its usability to evaluate the correlation between VRQOL and early glaucoma stages.
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