Facteurs de risque : la myopie

Controversy exists in the literature concerning the role of axial myopia as a risk factor for primary open-angle glaucoma. Epidemiologic evidence suggests that moderate and especially high myopia with a refractive error exceeding −6 D is a risk factor for the development and the progression of glaucomatous optic neuropathy, with a twofold to threefold increased risk of glaucoma compared with that of nonmyopic subjects. This risk has been proven to be independent of other glaucoma risk factors and intraocular pressure (IOP). Myopic eyes have slightly although probably not clinically relevant, higher IOPs than emmetropic or hyperopic eyes. Selection bias could account for some of the reported association between glaucoma and myopia given that myopic subjects are likely to consult their ophthalmologist more frequently and glaucoma is underdiagnosed in myopic patients due to the great variability of their optic disc morphology, especially in high myopia, and the difficulty to interpret their visual field. The weakness of the fibroglial matrix of the nerve fibers at the optic disc together with the structural alterations in the lamina cribrosa and choroid, could contribute to the high susceptibility of the optic disc to IOP fluctuations and to increasing the risk of glaucomatous neuropathy, especially in high myopic eyes. Special attention will be given to patients with mild myopia who present with both elevated IOP levels and a positive family history. On the other hand, high myopic subjects should be screened for glaucoma at closer intervals. Moreover, after appropriate adjustments for deviations in central corneal thickness have been made, IOP greater than 17 mmHg must already be regarded as critical and initiation of medical treatment considered.