Author reply

We are grateful to Dr. Hwang for providing lucid remarks on the potential instability of Bruch's membrane opening (BMO) in myopic eyes. We have argued that the BMO is a true anatomic border from which neuroretinal rim measurements can be made; however, if BMO migrates, it could call into question the validity of any BMO-based measurements, whether it is a horizontal rim width measurement made currently in optical coherence tomography (OCT) devices or a minimum rim width measurement (BMO-MRW) as proposed. In reality, although we share Dr. Hwang's concern, there is little understanding to date on the extent and nature of BMO migration in myopia. To date, there is evidence only from experimental primate glaucoma and in glaucoma patients undergoing glaucoma surgery, that large changes in intraocular pressure do not affect BMO. Naturally, longitudinal studies on the nature of deep optic nerve head changes in progressive glaucoma are being carried in our laboratories and others.