Encroachment of the retina and choroid onto the nasal portion of the optic nerve head in high myopia: visual and anatomical manifestations

Abstract

Myopia (short-sightedness/near-sightedness) is widespread and is increasing rapidly worldwide! We study a common, but rarely considered complication of high myopia known as nasal myopic super-traction (or super-involution), or encroachment of the retina and choroid onto the optic nerve head (disc) , and associated anatomical, physiological, and visual manifestations. This paper provides the foundation for associated extended SCE-1 studies. Here, histological records are presented; optical coherence tomographic (OCT) findings of this disorder are introduced; and perimetric data were obtained using fundus camera perimetry. We relate these data to visual functions measured upon and adjacent to the optic nerve head of the eye (the disc). In a separate paper in this issue (Chang et al., J. Mod. Opt. 2009, 20, 2272), the Stiles–Crawford effect of the first kind (SCE-1) was used to study photo-receptor alignments, and associated transient changes in photoreceptor alignments recorded using the same test subjects. We sought to understand better nasal myopic super-traction and its complications. We considered associated affects on the retinal pigment epithelium (RPE), nerve fiber bundles on the optic nerve head, etc. We assessed visual functions upon and about the optic nerve head. We demonstrated unique OCT properties in the disc-area in high myopia, evidence of disc hyperemia, reported the presence of maintained on-the-disc visual responses in over-ride tissues, and recorded reductions in visual sensitivity in retinal tissues translated onto/upon the disc. On-the-disc retinal and choroidal over-rides in high myopia remain viable, but exhibit reduced visual sensitivity; reveal time-varying alterations in photoreceptor alignments; and there exists evidence for on-going physical changes occurring in these over-ride tissues.