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 location. Most ozone (about 90%) is found in the stratosphere, which begins about 10â16 kilometers (6â10 miles) above Earthâs surface and extends up to about 50 kilo-meters (31 miles) altitude. The stratospheric region with the highest ozone concentration is commonly known as the âozone layerâ (see Figure Q1-2).ost ozone (about 90%) is found in the stratosphere, which begins about 10â16 kilometers (6â10 miles) above Earthâs surface and extends up to about 50 kilo-meters (31 miles) altitude. The stratospheric region with the highest ozone concentration is commonly known as the âozone layerâ (see Figure Q1-2).