We read with interest the article “Macular Choroidal Thickness in Children: The Shandong Children Eye Study” by Zhang et al.
1 The authors describe their evaluation of choroidal thickness (CT) with enhanced-depth optical coherence tomography (OCT) imaging in 972 Chinese children 6 to 18 years old.
The authors found that as against adults where CT is the highest beneath the fovea, the choroid was thickest temporally 500 μm from the fovea. The authors cite similar results from the literature. They mention that these results were due to migration of fovea or the choroid over time. We believe that these interesting results may be due to stronger ciliary body muscle tone known to be present in children.
2 Furthermore, as both the ciliary body and the choroid originate from the same developmental layer and there is no anatomical boundary between the two, the ciliary muscle would exert a pull on the semirigid choroid during near focusing in the OCT examination. As the optic disc forms a rigid landmark, the choroid gets pulled temporally. The authors noted CT to be the least nasally to the fovea, in support of our hypothesis. Also, all the OCT examinations had been performed before instillation of cycloplegic drugs.
This theory can be proven if the thickest measurement of choroid is found to gradually move toward the fovea with advancing age. We congratulate the authors on their interesting results and keenly await their reply.