High Myopia

This is caused by elongation of the eyeball and can lead to complications such as lacquer craks in Bruch’s membrane, areas of atrophy of the retinal pigment epithelium (RPE) and choriocapillaris, macular holes, paravascular lamellar holes and retinal cysts, macular retinoschisis and choroidal neovascularisation. There is also an increased risk of glaucoma.

Macular retinoschisis is present in between 9% and 24% of patients with high myopia and a posterior staphyloma, and can progress to macular hole and subsequent retinal detachment.  About 20% of patients with paravascular lamellar holes had macular retinoschisis and these conditions appears to be related.

An indication that paravascular retinal cysts/holes are present can be made by fundus examination when areas of darkening (retinal rarefaction) are seen adjacent to retinal veins. Unlike the similar process occuring at the macula (which can lead to a myopic retinal detachment), these are of no great clinical significance.