Data on vitrectomy. 1  Patients with proliferative retinopathy have a 33% risk of a vitreous haemorrhage at some time. 2  About 25% of these haemorrhages are recurrent or severe and need a vitrectomy. 3  After vitrectomy about 20% bleed needing a washout.  After vitrectomy, 33% have vision better than 6/18. 3% develop rubeotic glaucoma.
The Earth's atomospheric ozone layer is located in the tropopause, which is located just. above the troposphere. The tropopause is the bottom limit of the stratosphere several. miles above the surface of the Earth.
The ozone layer is a region with a relatively high concentration of ozone, and is located near the bottom of the stratosphere. It is located 8 to 50km above sea level. The alt â¦ itude varies with latitude, placing the stratosphere and the ozone layer closer to the Earth's surface over the poles.t is in the stratosphere, located 8 to 50km above sea level. The ozone layer surrounds the earth, meaning that it's wrapped around earth.