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Many studies have confirmed the strong association between myopia and glaucoma. Populationbased studies have established myopia as a risk factor for development of glaucoma.1 Controversy remains, however, with respect to the question of whether or not myopia is an independent risk factor for glaucoma progression.
Lee et al. examined myopic glaucomatous eyes with documented visual field (VF) progression to determine the velocities of both global and regional VF progression. The velocity of VF progression in these patients was compared with that in the non-myopic group. Their main findings were similar VF progression rates globally and regionally, after controlling for clinical factors related to VF progression. The proposed mechanism of myopia as a risk factor for glaucoma progression is the structural weakness of the optic nerve head and thinning of the lamina cribrosa and/or surrounding sclera resulting from globe elongation. According to this theoretic framework, myopia-related structural changes might make the optic nerve more susceptible to intraocular pressure (IOP)-related strain. Such structural changes, however, probably cease to pose a threat of further damage once the progressive thinning and tilting become stabilized. The authors suggest, therefore, that myopic disc change may not be an independent risk factor for rapid VF progression in progressive glaucomatous eyes.
There are several limitations to this study. First, due to the inherent nature of the retrospective design, it lacked a non-treatment control group as well as any target IOP setting standardization. If the patients are truly progressing, it remained unclear whether progression was due primarily to myopia or glaucoma. Also, in myopic glaucoma patients, the role of IOP lowering treatment and the correct target IOP ranges should be further elucidated. It would be interesting to know if prospective controlled studies can make the present data more relevant.