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.
Ozone occurs in two layers of the atmosphere. The ozone that is commonly associated with ozone depletion and the ozone hole is in the stratosphere, a layer that extends upward from about 10 to 30 miles (15 to 50 kilometers) above the earth.zone occurs in two layers of the atmosphere. The ozone that is commonly associated with ozone depletion and the ozone hole is in the stratosphere, a layer that extends upward from about 10 to 30 miles (15 to 50 kilometers) above the earth.