Alex W. Hewitt spoke at the 2014 ARVO Annual Meeting to present the results of the 20-year follow-up of his Western Australian Conception Study (Raine Study). The study involved 946 young adults and found that: high serum vitamin D concentrations were associated with a low prevalence of myopia or that high vitamin D status reduced the risk of myopia. Hewitt and colleagues considered myopia to be present when the mean equivalent spherical lens was above -0.5 D, a criterion by which 220 of the study participants were myopic. Hewitt noted that: all patients underwent ciliary muscle paralysis optometry, conjunctival UV autofluorescence testing (which measures the degree of damage to the eye from UV exposure, which has been shown to correlate positively with time spent outdoors); serum 25(OH) vitamin D was measured as circulating vitamin D levels; and the data were deseasonalized. Myopia-related factors: Asian origin, continuing education, family history of myopia, and relatively low outdoor activity. Hewitt noted that the correlation was first suggested in 2011 and the results of this study support previous findings, finding a weak positive correlation between conjunctival autofluorescence and vitamin D levels and a weak negative correlation between refractive error and vitamin D concentration. In addition, the investigators suggest that further research is needed to clarify whether high vitamin D levels are really protective against myopia or just evidence of sunlight exposure.