Glaucoma is a disease which affects between one and two percent of all individuals aged over
40 years. According to recent Canadian National Institute for the Blind figures, it is the
second largest specific cause of blindness in this country. The most common form of glaucoma,
open-angle glaucoma, is incipient and typically results in a progressive loss of vision
without symptoms due to damage to a structure inside the eye called the optic nerve head.
Although the most important known risk factor for the development of open-angle glaucoma is
high intraocular pressure (the pressure within the eyeball), a number of researchers have
shown that a sizeable proportion of patients continue to lose vision in spite of successful
treatment to lower their intraocular pressure. This finding suggests that there may be
additional risk factors involved. Ocular vasospasm (the inability of certain blood vessels to
dilate and increase blood flow according to the needs the eye) and vascular disease are among
other factors implicated but their roles have not yet been fully investigated. The Canadian
Glaucoma Study Group proposes to investigate the role of risk factors, including vasospasm
and vascular disease, involved in the progression of open-angle glaucoma. We will recruit 410
patients with open-angle glaucoma across 4 centres (Halifax, Vancouver, Montreal and Toronto)
who will be treated by experienced investigative ophthalmologists according to a uniform
standard protocol to ensure that all patients are managed in the same manner. The patients
will be followed meticulously with the most modern and accurate tests available every four
months for a period of 5 years to determine whether progression has taken place. Visual
function will be measured using two techniques called conventional perimetry and
blue-on-yellow perimetry, and optic nerve heads will be examined with a special scanner
capable of three-dimensional imaging. By defining both the ocular and systemic profiles of
patients who progress and do not progress, we may be able to identify which patients will
benefit from the standard treatment of intraocular pressure reduction, such as that
prescribed in the study. More importantly, we will identify the characteristics of patients
who do not benefit from standard treatment, so that alternative ones may be developed. Such
studies are clearly necessary, but have not yet been conducted. We believe that the proposed
study will increase our knowledge of open-angle glaucoma and reduce its impact on blindness
and visual disability.
Phase:
N/A
Details
Lead Sponsor:
Dalhousie University
Collaborators:
Allergan Canadian National Institute for the Blind Glaucoma Research Society of Canada Merck Frosst Canada Ltd. Pfizer