Prevalence of chronic ocular diseases in a genetic isolate: The Norfolk Island Eye Study (NIES)
Sherwin, JC and Kearns, LS and Hewitt, AW and Ma, Y and Kelly, J and Griffiths, LR and Mackey, DA, Prevalence of chronic ocular diseases in a genetic isolate: The Norfolk Island Eye Study (NIES), Ophthalmic Epidemiology, 18, (2) pp. 61-71. ISSN 0928-6586 (2011) [Refereed Article]
Purpose: Over 40% of the permanent population of Norfolk Island possesses a unique genetic admixture
dating to Pitcairn Island in the late 18th century, with descendents having varying degrees of
combined Polynesian and European ancestry. We conducted a population-based study to determine
the prevalence and causes of blindness and low vision on Norfolk Island.
Methods: All permanent residents of Norfolk Island aged ≥ 15 years were invited to participate.
Participants completed a structured questionnaire/interview and underwent a comprehensive
ophthalmic examination including slit-lamp biomicroscopy.
Results: We recruited 781 people aged ≥ 15, equal to 62% of the permanent population, 44% of whom
could trace their ancestry to Pitcairn Island. No one was bilaterally blind. Prevalence of unilateral
blindness (visual acuity [VA] < 6/60) in those aged ≥ 40 was 1.5%. Blindness was more common in
females (P = 0.049) and less common in people with Pitcairn Island ancestry (P < 0.001). The most
common causes of unilateral blindness were age-related macular degeneration (AMD), amblyopia,
and glaucoma. Five people had low vision (Best-Corrected VA < 6/18 in better eye), with 4 (80%)
due to AMD. People with Pitcairn Island ancestry had a lower prevalence of AMD (P < 0.001) but
a similar prevalence of glaucoma to those without Pitcairn Island ancestry.
Conclusions: The prevalence of blindness and visual impairment in this isolated Australian territory
is low, especially amongst those with Pitcairn Island ancestry. AMD was the most common cause of
unilateral blindness and low vision. The distribution of chronic ocular diseases on Norfolk Island
is similar to mainland Australian estimates.
blindness, epidemiology, genetics, glaucoma, macular degeneration, Norfolk Island, Pitcairn Island, population isolates, viual impairment, cardiovascular diease, cataract