RE: Retail scan point

[Free Spirit <FRANK@rover.bsd.uchicago.edu>]

>From: "Randy Ross" <RNROSS@BCSC02.GOV.BC.CA>
>I did a study on some class 2 (.9mW/cm2) HeNe alignment lasers used on patient
> ... I concluded that the patients had nothing to worry about as far as eye
damage goes.  there was a safety factor of 200 ie the irradiance levels at the
cornea were 200 times below the threshold for injury.   So I decided to see wha
t it was the patients were complaining about.  Well let me tell you it was
VERY bright.  It was like looking into the sun.  But it was not hazardous. ...

	Our patients (and technologists,) also occasionally ask/complain/worry
	about the brightness of our positioning lasers. We have come to the
	same conclusions, but do note that positioning lasers seem to be right
	at the edge where the eye starts to react, not where actual damage
	may occur. We are definitely dealing with a perception problem, rather
	than a real problem . However we must treat the problem so we do the
	following:

	1/ Measure laser output and adjust the filters in the unit to make
	   sure we stay below .9mw after fixing/retubing. etc any laser.

	2/ Further filter/adjust any lasers that have an abnormally short
	   working distance.

	We still get technologists/medics who say, "Laser so-and-so is 
	brighter than the rest, is it ok?" Of course it's brighter, it was
	just replaced. That's life.

	In fact, we have actually had patients who think that the lasers
	are treatment devices, rather than simply positioning aids. When
	faced with misconceptions like this, I give up. Rather than trying to
	educate the masses, and tell them "That's way below the level of
	any possible harm..." I just say, "No Sir/Ma'm, we check those with
	our power level meters and they are safe."