A thin choroid at age 11 doesn’t seem to predict a child will have axial elongation by the time they turn 16 or increase their risk of developing myopia, a study in BMC Ophthalmology reports. Still, the team of researcher from Denmark also found children with longer eyes at age 11, and predominantly girls, had greater five-year axial elongation and a significantly higher risk of myopia by the time they reached 16.

 The investigation enrolled the right eyes of 714 children (317 boys) who were examined when they were approximately 11 and 16 years old. The investigators measured axial length using interferometry and choroidal thickness with spectral-domain OCT. The study defined myopia as non-cycloplegic subjective spherical equivalent refraction of -0.50D or less.

When the children turned 16, axial length increased from baseline by 243μm in eyes without myopia (n = 630) compared with 454μm in myopic eyes (n = 84).

A thicker baseline subfoveal choroid was associated with increased five-year axial elongation after adjustment for baseline axial length in non-myopic eyes but not in myopic eyes, the researchers noted.

Longer baseline axial length was associated with greater five-year axial elongation in both myopic and non-myopic eyes, and the odds for incident myopia increased with 1.57 per mm longer axial length at baseline.

Investigators also reported axial length increased more in girls than boys, and girls had a higher risk for incident myopia among the children without myopia at baseline.

Since longer baseline axial length was a predictor for larger subsequent five-year eye length growth in both myopic and non-myopic eyes—and the odds of incident myopia increased along with an increase in baseline axial length—children who developed myopia were already on track to develop the condition by the time they were 11, which was a consistent finding with previous research.

Consequently, children with long eyes at an early age could be targeted for preventive myopia strategies, such as increased time spent outdoors, the study noted. 

Hansen MH, Kessel L, Li XQ, et al. Axial length change and its relationship with baseline choroidal thickness— a five-year longitudinal study in Danish adolescents: the CCC2000 eye study. BMC Ophthalmology. April 15, 2020. [Epub ahead of print].