Abstract
Purpose::
To examine macular and peripapillary nerve fiber layer (NFL) thickness in amblyopia.
Methods::
The Sydney Childhood Eye Study is a population-based study of children’s eye health. Participants included 4118 (76.5%) of 5382 eligible children recruited from a random cluster sample of 34 primary schools and 21 high schools in the metropolitan area of Sydney, Australia, respectively. Examinations were conducted during 2003-05. Among the 3529 children (85.7%) in this report, the median ages of the two cohorts were 6 years (n=1395) and 12 years (n=2134). Comprehensive examinations included determination of best visual acuity (BVA), cycloplegic autorefraction, cover testing to identify strabismus and optical coherence tomography (StratusOCT, Carl Zeiss). Amblyopia was defined as BVA<0.3 logarithm of the minimum angle of resolution units not explained by underlying eye or visual pathway abnormalities. Analyses compared macular and peripapillary NFL thickness in amblyopic and non-amblyopic eyes, adjusting for confounders where appropriate.
Results::
The foveal minimum thickness was greater (by 5.0µm, p<0.05) in amblyopic eyes compared to the normal fellow eye and compared to right eyes of non-amblyopic children (by 12.1µm, p<0.05), adjusted for age, gender, height, ethnicity, axial length and cluster sampling. Amblyopic eyes also had thicker central maculae (1-mm diameter region) in both comparisons, although these differences were not statistically significant. The inner macular ring (outer radius 1.5mm) was thinner in amblyopic than in normal fellow eyes. Children who had untreated unilateral amblyopia had a significantly increased (p<0.05) inter-ocular difference in central macular thickness than those who previously received treatment. Peripapillary NFL thickness was not significantly different between amblyopic and normal fellow eyes or normal eyes of non-amblyopic children.
Conclusions::
Central macular thickness may be increased in amblyopia and this outcome may be reversed with treatment. It is not certain, however, if the observed increase in macular thickness precedes or follows the development of amblyopia. Further studies are needed, given the previous postulate of a cortical or lateral geniculate site for amblyopia No differences in peripapillary NFL thickness were found in amblyoipic compared to normal eyes.
Keywords: amblyopia • macula/fovea • nerve fiber layer