Multiple Factors Causing Myopia and the Possible Treatments: A Mini Review

Myopia is a common cause of vision loss, with uncorrected myopia the leading cause of distance vision impairment globally. Individual studies show variations in the prevalence of myopia and high myopia between regions and ethnic groups, and there continues to be uncertainty regarding increasing prevalence of myopia.

To measure macular choroidal thickness (CT) in highly myopic eyes using enhanced depth imaging optical coherence tomography (OCT). Retrospective, observational case series. Enhanced depth imaging OCT images were obtained in highly myopic eyes (> or =6 diopters [D]). Images of CT were obtained by positioning a spectral-domain OCT device close enough to the eye to acquire an inverted image. CT was measured from the outer border of the retinal pigment epithelium to the inner scleral border at 1000-mum intervals of a horizontal section from 3 mm temporal to the fovea to 3 mm nasal to the fovea. Statistical analysis was performed to evaluate CT at each location and to correlate CT with age and refractive error. The mean age of the 31 patients (55 eyes) was 59.7 years (+/- 17.6 years; range, 24 to 90 years), and the mean refractive error was -11.9 D (+/- 3.7 D). The mean subfoveal CT was 93.2 microm (+/- 62.5 microm) and was correlated negatively with age (P = .006), refractive error (P < .001), and history of choroidal neovascularization (P = .013). Regression analysis suggested that subfoveal CT decreased by 12.7 mum for each decade of life and by 8.7 microm for each D of myopia. The choroid in highly myopic eyes is very thin and undergoes further thinning with increasing age and degree of myopia. Abnormalities of the choroid may play a role in the pathogenesis of myopic degeneration.