The College of Optometrists

on the dicon ld400 visual field screener, what is the difference between the quantiying defects program, suprathreshold program and threshold program? which one is best for screening and which for various suspected defects (eg glaucoma)?

its all in the book (which I don't have to hand). But if memory serves me, they liken vision to a hill in a sea of blindness. Suprathreshold is their screen test. It is pretty good and does work. Supra thresh does each point twice at different luminosities after working out the average threshold for the whole hill (ie how much sticks out of the water). I forget the quantifying test. Time is important - if the screen is quick - then their can't be much wrong- if it is not sure it grinds round and round. I liked the supra thresh for gl screening - but it demands ovre 5 mins. Its a good screener - but not popular.

sorry palf - have used dicon a lot but didn't understand your explanation. my understanding - never having seen the handbook - is: quant defects is just that - missed points are then effectively full thresholded. So you start with a suprathreshold and then dip into threshold for misses. supra is as it says as is threshold. While I became used to it I was never entirely sure about it print outs as you came to rely on the grey scale. Much prefer the stat analysis of Henson or Humphreys. Good screener?

I agree dburns - it does sound a muddle! I will try and turn up the book.palf