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.
Causes. The main cause of Ozone Depletion are CFCs. CFC's drift in the environment until they reach the stratosphere. The UV radiation splits the chlorine from CFC's which attracts one of the three ozone atoms and destroys the ozone into ordinary oxygen.CFC's were ordinarilly used to replace the ammonia and its effects.he UV radiation splits the chlorine from CFC's which attracts one of the three ozone atoms and destroys the ozone into ordinary oxygen. CFC's were ordinarilly used to replace the ammonia and its effects.