A myopic shift in Australian Aboriginals: 1977-2000

Abstract

Background/aims: The prevalence of myopia has been reported to have increased in a number of population groups. We compared the refraction of Australian Aboriginal adults in 2000 with data collected in 1977 to assess whether there had been a change in the prevalence of myopia.

Method: Australian Aboriginal adults aged 20 to 30 years old were selected from Central Australian communities in 2000. Refraction was determined by noncycloplegic autorefraction. This was compared to mydriatic retinoscopy data collected in 1977. "Observer trials" were undertaken to assess the comparability of noncycloplegic autorefraction measurements and cycloplegic retinoscopy. Spherical equivalence cylinder and spheric were determined for all right and left eyes and compared using an analysis of variance.

Results: A total of 128 adults (58 males, 70 females) were examined in 2000 and compared with 161 adults (107 males, 54 females) examined in 1977. The mean spherical equivalent in 2000 was -0.55 D +/- 0.88 D and in 1977 was +0.54 D +/- 0.81 D. The difference of -1.09 D was highly significant (F = 126, P < .001). Intraclass correlation coefficients showed good agreement between noncycloplegic autorefraction and cycloplegic retinoscopy. Neither gender, schooling, nor diabetes was associated with an increased risk of myopia.

Conclusions: There appears to have been a significant shift toward myopia in Australian Aboriginals between 1977 and 2000. The cause of this myopic shift is unknown but mirrors that observed in other populations in recent years.