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 layer. ozone layer or ozonosphere, region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12â30 mi (19â48 km) above the earth's surface. Ozone in the ozone layer is formed by the action of solar ultraviolet light on oxygen.zone layer. ozone layer or ozonosphere, region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12â30 mi (19â48 km) above the earth's surface. Ozone in the ozone layer is formed by the action of solar ultraviolet light on oxygen.