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.
Environmental Effects of Ozone Layer Depletion: 1994 Assessment. United Nations Environment Programme, Nairobi, Kenya, 1994. Health, solar UV radiation and environmental change. A Kricker, BK Armstrong and RD Burton (eds), Lyon, International Agency for Research on Cancer (IARC Technical Report 13), IARC 1993.