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| Author | Subject: glaucoma |
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 pt
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glaucoma
Jun 18, 2005 18:48:25 how much damage needs to occur in glaucoma before a defect shows up? |
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ams
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RE: glaucoma
Jun 18, 2005 19:04:32 approx 50% nerve fibre damage before a field defect shows up |
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Homer
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RE: glaucoma
Jun 19, 2005 09:30:29 I've heard 40% (just to split hairs) and if you see a disc haemorrhage it can take up to a year and a half before a corresponding defect shows. |
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ored
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RE: glaucoma
Jun 19, 2005 22:48:17 and i've heard 30% :S |
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dburns
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RE: glaucoma
Jun 19, 2005 23:07:28 Apparently the original paper citing 50% loss never actually said that - it gave a range. Also the cadifers the eyes were taken from were usually octogenarians. truth is need more research on normal nerve fiber counts. So to say 50% loss before a defect shows is not the whole truth. For some pxs yes, others no. |
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jonesal2
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RE: glaucoma
Jun 25, 2005 13:00:47 The 50% figure that is banded about for neural loss in glaucoma before visual field defect is manifest is from the original paper by Harry Quigley based on kinetic perimetry and only about 10 eyes (I think). This data has been re-done using static perimetry by Kerrington & Quigley and suggests that for a central defect there needs to be about 35% neural loss but in the periphery, especially the temporal retina (nasal field), it can be as little as 10%.
For a disc heam you are more lightly to see a RNFL defect with red free first. A |