Myopic Degeneration
SALIENT FEATURES
Myopic degeneration may occur in eyes that typically have a refractive error exceeding -6.00D or axial length of at least 26.5 mm along with posterior pathology due to axial elongation.
The most common retinal pathology in myopic degeneration is the development of posterior staphyloma.
Posterior staphyloma may have two visually significant components: tractional and degenerative components.
Tractional component: the bulging staphyloma may result in differential stretching of the retinal layers. While the outer layers may be more elastic and expand with the staphyloma, the internal limiting membrane may become more taut resulting in stretching of the overall retina. This may progress to separation of the neurosensory and epiretinal layers (macular foveoschisis) or progress to a macular hole (see Chapter 35, Myopic Macular Schisis and Tractional Retinal Detachment).
Degenerative component: the bulging staphyloma results in choroidal thinning and choroidal neovascularization. This presents with lacquer cracks and retinal pigment epithelium (RPE) atrophy.
Macular foveoschisis is best observed with optical coherence tomography (OCT).
Fluorescein angiography (FA) in combination with OCT is the historic gold standard for detecting choroidal neovascularization in myopic degeneration.
Optical coherence tomography angiography (OCTA) may be used as an noninvasive alternative to FA for visualizing vessels.
 FIGURE 26.1 Myopic degeneration with associated myopic foveoschisis. Taut internal limiting membrane (ILM) and epiretinal membrane (ERM) (yellow arrow) are noted nasally with underlying myopic schisis. Subretinal fluid is also present (arrowhead). Diffuse ellipsoid zone attenuation is present with underlying choroidal thinning (white arrow). Significant curvature of the posterior eye wall is noted, consistent with high myopia. |
OCT IMAGING
Axial elongation results in steep curvature of the retina that is well-visualized on OCT (Figure 26.1).
Depending on the location and staging of the staphyloma, posterior staphyloma may present as a steep curve with a radius that is smaller than the radius of the rest of the eye. It may also present as an inward bulge from the sclera.
Macular foveoschisis typically presents on OCT with separation of either the outer plexiform, inner plexiform, and/or nerve fiber layers (Figure 26.1). Thin bands of retinal material bridge the tissue.
Compound myopic macular foveoschisis may also occur, resulting in separation of multiple layers of the retina.
Macular holes may also develop and can, in certain cases, progress too macular detachments.
Myopic degeneration demonstrates retinal thinning, RPE irregularity, significant choroidal thinning, ellipsoid zone attenuation, and outer retinal atrophy (Figure 26.1). RPE atrophy can also develop. Spontaneous subretinal hemorrhages may develop.
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