Prevalence and predictors of refractive error in a genetically isolated population: the Norfolk Island Eye Study
Sherwin, JC and Kelly, J and Hewitt, AW and Kearns, LS and Griffiths, LR and Mackey, DA, Prevalence and predictors of refractive error in a genetically isolated population: the Norfolk Island Eye Study, Clinical and Experimental Ophthalmology, 39, (8) pp. 734-742. ISSN 1442-6404 (2011) [Refereed Article]
Background: We aimed to determine the prevalence
and associations of refractive error on Norfolk Island.
Design: Population-based study on Norfolk Island,
Participants: All permanent residents on Norfolk
Island aged $15 years were invited to participate.
Methods: Patients underwent non-cycloplegic auto-
refraction, slit-lamp biomicroscope examination and
biometry assessment. Only phakic eyes were
Main Outcome Measures: Prevalence and mul-
tivariate associations of refractive error and
Results: There were 677 people (645 right phakic
eyes, 648 left phakic eyes) aged $ 15 years were
included in this study. Mean age of participants was
51.1 (standard deviation 15.7; range 15–81). Three
hundred and seventy-six people (55.5%) were
female. Adjusted to the 2006 Norfolk Island popula-
tion, prevalence estimates of refractive error were
as follows: myopia (mean spherical equivalent
$-1.0 D) 10.1%, hypermetropia (mean spherical
equivalent $ 1.0 D) 36.6%, and astigmatism 17.7%.
Significant independent predictors of myopia in the
multivariate model were lower age (P < 0.001),
longer axial length (P < 0.001), shallower anterior
chamber depth (P = 0.031) and increased corneal
curvature (P < 0.001). Significant independent pre-
dictors of refractive error were increasing age (P <
0.001), male gender (P = 0.009), Pitcairn ances-
try (P = 0.041), cataract (P < 0.001), longer axial
length (P < 0.001) and decreased corneal curvature
(P < 0.001).
Conclusions: The prevalence of myopia on Norfolk
Island is lower than on mainland Australia, and the
Norfolk Island population demonstrates ethnic dif-
ferences in the prevalence estimates. Given the sig-
nificant associations between refractive error and
several ocular biometry characteristics, Norfolk
Island may be a useful population in which to find
the genetic basis of refractive error.