NHMRC Glaucoma Guidelines - ANZGIG

NHMRC GUIDELINES FOR THE SCREENING, PROGNOSIS, DIAGNOSIS, MANAGEMENT AND PREVENTION OF GLAUCOMA
Chapter 6 – Identifying those at risk of developing glaucoma
Risk factors identified from patient history
Age
Advancing age is a major risk factor for the development of glaucoma. The prevalence of glaucoma
is four to 10 times higher in the older age groups than in individuals in their forties (American
Optometric Association [AOA] 2002). In the Australian Melbourne Visual Impairment Project, this
difference was substantially larger. It was 17 times more likely that participants aged 80 years and
older would have glaucoma, than participants aged less than 50 years (Weih, Manjan, McCarty et
al 2001). Pooled data reported by Burr, Mowatt, Hernandez et al (2007) indicate that the overall
prevalence of open angle glaucoma (OAG) was 0.3% (95% CI 0.1% to 0.5%) in people aged
40 years, and increased to 3.3% (95% CI 2.5% to 4.0%) in people aged 70 years. Damage to the
optic nerve from glaucoma is uncommon before the age of 50 years in Caucasians, however it
appears to occur at least a decade earlier in people of African descent (AOA 2002).
Evidence Statements
• Evidence strongly indicates that Caucasians over the age of 50 years undertake regular ocular health checks.
• Evidence indicates that individuals of African descent over the age of 40 years undertake regular ocular
health checks.
Point of note
Caucasians over 50 years of age are at moderate risk, and those over 80 years of age are at high
risk of developing glaucoma. A rational approach to screening for glaucoma is therefore required
for Caucasians over the age of 50 years. For Caucasians without other significant risk factors
for glaucoma, a glaucoma assessment could be included in the 45-49 year general health check
(Medicare Item Number 717) and also in the Health Assessment for people aged 75 and over
(Medicare Item Number 700 or 702) undertaken by general medical practitioners.
Family history and genetics
A family history of glaucoma puts an individual at greater risk of developing the disease (AOA 2002).
In close relatives of individuals with primary open angle glaucoma (POAG), the prevalence is three
to six times that of the general population. The incidence of the disease in first-degree relatives is
three to five times that found in the general population. The 22% lifetime risk for glaucoma found in
relatives of patients with glaucoma is almost 10 times that of controls (AOA 2002).
Burr et al (2007) conducted a meta-analysis of four studies that indicated an association between
developing OAG and a positive family history, with the strongest association being observed
between siblings. However, Burr et al (2007) expressed reservations about this association, noting
that most of the studies relied on the verbal reporting of family history of glaucoma rather than
clinical examination. Thus the results may be open to misclassification.
Mutations in transcription factor genes have been found to be responsible for developmental
disorders associated with childhood glaucoma (AOA 2002). The following genetic syndromes have
high associations with childhood glaucoma: Nail Patella Syndrome with the LMX1B gene, Axenfeld
Rieger Syndrome/Anterior segment dysgenesis with the PITX2 and FOXC1 genes and Aniridia
with the PAX6 gene. Patients with these syndromes or mutations are usually followed closely for
glaucoma (Mackey & Craig 2003). Congenital glaucoma is associated with Cyp1B1 mutations in
50 National Health and Medical Research Council