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A.W. Hewitt, S.L. Bennett, J.L. Poulsen, J.H. Fingert, P.M. McCartney, E.M. Stone, J.E. Craig, D.A. Mackey; The Optic Disc in Myocilin Glaucoma . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5445.
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© ARVO (1962-2015); The Authors (2016-present)
Approximately 1 in 30 unselected patients with primary open–angle glaucoma have a mutation in their myocilin gene. The aim of this study was to describe the morphological features of the optic nerve head in myocilin glaucoma.
Subjects were recruited through the Glaucoma Inheritance Study in Tasmania. 62 patients with a myocilin mutation (either: Gln368Stop; Pro370Leu; Thr377Met; Ile379Thr; Asp380Gly; or Asn420Tyr) were matched by visual field severity to 115 patients known not to have a myocilin mutation. Simultaneous stereoscopic disc photographs were taken using a Nidek fundus camera 3–Dx/F (Nidek, Gamagori, Japan). Quantifiable analysis of optic disc area, optic cup area, neuroretinal rim area and parapapillary atrophy (PPA) was performed stereoscopically using the StereoDx software with a Z–screen. Subjective grading of the cup depth, lamina cribrosa pore shape and orientation, as well as slope of the neuroretinal rim was performed by an examiner masked to each subject’s mutation status. Mutation screening was conducted either using either direct sequencing or SSCP. A case–control design was adopted.
Patients with a myocilin mutation were diagnosed earlier (p<0.0001), and had higher maximum recorded intraocular pressures (p<0.0001) than control subjects. There was no significant difference in global disc area (p=0.99), global neuroretinal rim area (p=0.06), alpha–PPA (p=0.06), beta–PPA (p=0.49) or slope of neuroretinal rim (p=0.70). Additionally there was no significant difference in visible lamina cribrosa morphology between mutation carriers and non–mutation carriers. Although disc haemorrhages were found more frequency in non–mutation carriers, this was not significant after correction for multiple testing.
No structural or morphological difference of the optic nerve head could be delineated in pooled subjects who had a myocilin mutation, when compared to non–myocilin glaucoma.
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