2020–2021 BCSC Basic and Clinical Science Course™
12 Retina and Vitreous
Part II: Disorders of the Retina and Vitreous
Chapter 10: Myopia and Pathologic Myopia
The Optic Nerve
In eyes with pathologic myopia, the optic nerve head is undercut by a shifted Bruch membrane opening, the scleral canal may be stretched and tilted, the circle of Zinn–Haller is greatly enlarged, and the optic nerve may ordinarily appear stretched and pallorous. Glaucoma is much more common in highly myopic eyes and frequently goes undetected. Measuring the retinal nerve fiber layer with OCT is problematic because of the varying shape of the eye, the potential for schisis, and because normative databases were developed for eyes that are not pathologically myopic. Visual field tests may show defects because of the shape of the eye, some of which can be “fixed” by using a refractive correction for that portion of the eye. Dehiscences in the lamina cribrosa are common in eyes with high myopia (Fig 10-9).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.