The Effect of Optical Defocus on the Choroidal Thickness: A Review

Sulaiman Aldakhil1, *
1 Department of Optometry, College of Applied Medical Sciences, Qassim University, Buraydah, Saudi Arabia

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© 2021 Sulaiman Aldakhil

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Optometry, College of Applied Medical Sciences, Qassim University, Saudi Arabia. P.O. Box 6699 Buraydah 51452, Buraydah, Saudi Arabia; Tel: 00966163015501; E-mail


The choroid is a heavily vascularized tissue located between the retina and sclera and plays a primary role in ocular metabolism. It has recently been suggested that the choroid has the ability to change its thickness and secretion of growth factors. This may play an important role during visual development by adjusting retinal position during growth to support emmetropisation; however, the mechanism by which changes in choroidal thickness (ChT) occur is unclear.

This relationship becomes an interesting topic in the clinical field, although conflicting evidence found that these changes in the choroidal thickness may not be associated with the development of refractive errors. Many reports have investigated the changes in the choroid and related factors that affect the ChT. Thus, this review will summarize the current literature related to choroidal thickness in different refractive error groups, determine the factors that influence the thickness of the choroid, and discuss in detail the relationship between the changes in the ChT and ocular elongation, and therefore, the effect of optical defocus on ChT and the development of the refractive error.

Keywords: Choroid, Choroidal thickness, Emmetropization, Ocular elongation, Optical defocus, Refractive errors.