Optic Disc Anomaly

Abstract

This chapter covers changes related to the optic disc and abnormalities in various ocular conditions. This chapter divided into the following sections. (1) The optic pit and its secondary retinoschisis. OCT in optic pit maculopathy demonstrates a combination of outer retinal layer detachment and retinoschisis in most cases. (2) Glaucoma, the most important section of this chapter, describes different changes that can be detected in glaucoma and important considerations in the interpretation of the retinal nerve fiber layer (RNFL) thickness profile. OCT can assess glaucoma using four parameters: (a) peripapillary RNFL (retinal nerve fiber layer) parameters, (b) optic nerve head parameters, (c) macular parameters, and (d) hemodynamic parameters. Pitfalls and artifacts in image acquisition and interpretation are discussed fully. (3) The myelinated nerve fiber layer in the optic disc area and other parts of the retina. In OCT, because the myelinated sheet of nerves can reflect light almost completely, we always have a highly reflective surface with strong shadowing of the underlying tissue. (4) Anterior ischemic optic neuropathy (AION). In early-stage AION, OCT shows a considerable increase in RNFL thickness that converts to a plateau and then atrophies in 6 months. (5) Optic disc drusen, which is a progressive disease; most cases lose the RNFL and show visual field defects in perimetry. “Lumpy-bumpy” internal reflectivity on OCT images strongly suggests drusen. (6) Papillitis and papilledema are described with other complementary tests and tips for differentiation between papilledema and papillitis.