Blood vessel diameter in glaucoma

Abstract

Glaucoma is a leading cause of visual disability in the UK and major referral reason between high street optometry and hospital based ophthalmology. The standard optometric tests used to determine necessity of referral are currently leading to a high false positive burden on glaucoma clinics. The disease of glaucoma is considered to be multifactorial in the reasons for its onset and progression. An increasing body of research proposes a vascular dysregulation hypothesis, and retinal artery diameter reduction, as a recognisable risk factor for both the onset and progression of glaucoma. The Heidelberg Retina Tomograph (HRT) is a commercially available laser scanning ophthalmoscope designed principally for the detection of glaucoma by evaluation of the optic disc neuroretinal rim. An additional ability of the HRT is to measure, via an interactive window, the blood vessels of the scanned image without the need for export of the image or magnification to view them in detail. This thesis contributes to the field of early glaucoma detection by measurement of artery diameter via the interactive window on the HRT machine. The volunteers were divided into three groups normal, glaucoma and ocular hypertensive (OHT) and followed over a period of one year to determine if vessel diameter changed in relation to visual field or neuroretinal rim parameters. The main results in this thesis show that artery diameter does change with glaucoma onset and that the HRT machine is a valid instrument for collection of this data.