Choroidal changes in human myopia: insights from optical coherence tomography imaging

Abstract

The choroid is a vascular tissue which plays a range of critical roles in the normal physiology of the eye, such as supplying the outer retina with oxygen and nutrients and the regulation of intraocular pressure. There is also substantial evidence, particularly from animal studies, that the choroid plays an important role in the regulation of eye growth and the development of common refractive errors like myopia. In recent years, advances in optical coherence tomography technology have improved our ability to image and measure the choroid in the human eye. Research using this technology over the past decade has dramatically improved our knowledge of the normal choroid, and its potential role in the regulation of eye growth and refractive error development. This review aims to provide an overview of recent work examining the normal human choroid, its changes with myopia and the possible role of the choroid in the mechanism regulating eye growth. Studies have demonstrated that choroidal thinning accompanies the development and progression of myopia, and have established a close link between eye growth and choroidal thickness changes. Dramatic thinning of the choroid is seen with high myopia, and associations are also observed between choroidal thinning and reduced vision, and the development of retinal pathology associated with high myopia. In the short-term, environmental factors known to be associated with myopia development and more rapid eye growth typically lead to a thinning of the choroid, whereas factors linked to a slowing of eye growth are typically associated with short-term choroidal thickening. Collectively, these findings suggest that the choroid is an important biomarker of eye growth in the human eye, and additional research to better understand the human choroid is likely to further our knowledge of the signals and pathways regulating eye growth, myopia development and progression.

Atropine Differentially Modulates ECM Production by Ocular Fibroblasts, and Its Ocular Surface Toxicity Is Blunted by Colostrum

“…It is nowadays evident that myopia is strongly correlated with the axial length of the eye and not with its refractive power [18]. The growth of the eye globe is a complex event, which appears to be regulated by signals coming from the retina and the choroid, independent from the brain [19,20]. Some described chemical mediators of this signaling mechanisms are dopamine [21], TGFβ [22], and melatonin [23].…”

Regional alterations in human choroidal thickness in response to short‐term monocular hemifield myopic defocus

“…These results suggest that exposure of the retina to a regionally distinct, rather than a spatially uniform, pattern of myopic defocus may provide additional cues to the eye that result in an increased response of the choroid to myopic defocus. An increase in choroidal thickness is thought to contribute to the long‐term slowing of ocular growth . Therefore, the greater thickening of the macular choroid in response to a regionally distinct, rather than spatially uniform imposed myopic defocus, may also provide a potential mechanism explaining the greater efficacy of bifocal and multifocal spectacle lenses, multifocal soft contact lenses and orthokeratology compared to the symmetrical defocus of bilateral myopic under‐correction in slowing the progression of myopia.…”

“…Research with animal models suggests that eye growth is influenced by retinal image defocus, with the choroid playing a significant role in mediating the effects of defocus on ocular growth and the development of refractive errors . Studies in a range of species show that a thinning or thickening of the choroid in response to hyperopic or myopic defocus results in a rapid movement of the retina towards the defocused image plane, followed by alterations in scleral growth that eventuates in the development of experimental myopia or hyperopia, respectively .…”

Axial length change and its relationship with baseline choroidal thickness – a five-year longitudinal study in Danish adolescents: the CCC2000 eye study

“…Experimental settings in both animals [9][10][11][12] and humans [8] show a modulation of choroidal thickness in response to visual inputs which also leads to choroidal secretion of scleral growth regulators [13]. Consequently, the choroid is believed to play an active part in eye growth regulation [14,15]. Eyes that develop myopia both experience a thinning of the choroid and an elongation of the eyeball [16,17] and a study following 101 Australian children over an 18 month period found an association between choroidal thinning and increasing axial length growth [18].…”