Barrier and Exciter filters

Mon, 7 Jan 2013 13:48:24 GMT

We have the FF450 Zeiss Fundus camera and are wondering if anyone has any experience with it. We are having problems with the contrast during the FAs.Our camera is over seven years old, the filters have never been changed and we are being told they never need changed on this camera. Any thoughts would be helpful.

Alyce Booth, C.O.T

George Washington Medical Faculty Associates

ambooth@mfa.gwu.edu

Mon, 7 Jan 2013 16:01:09 GMT

Some questions that may help find an answer to your problem...

Does this low contrast happen with every FA? Are your patients fully dilated? (could be patient related)

Have your FA's always seemed flat, or have they gotten gradually worse? Are you sure it's a contrast issue and not an exposure issue? (could be machine related)

How much dye are you injecting?

Do you have a service contract with your vendor? (you could always call in the pros)

Either way, I would first check the contrast setting on your capture software. We use Merge (OIS) and there is a radio button on the right side of the screen that sets contrast... I believe ours is set on 5 or 6. That may be a good place to start.

I'm sure we'll see more ideas from the group...

Gary

Mon, 7 Jan 2013 17:47:17 GMT

Gary did a great job of asking the appropriate troubleshooting questions. I'd add one more: do the images look flat on more than one monitor or just at the capture station. I would either export some images to view on another computer/monitor or move to a remote review station & see how they look. Monitors that aren't adjusted or calibrated can have a huge impact on how the images look. If the contrast is lacking on more than one monitor, I'd tweak the contrast/gamma settings.

Mon, 7 Jan 2013 19:24:40 GMT

Some questions that may help find an answer to your problem...
Does this low contrast happen with every FA? Are your patients fully dilated? (could be patient related)
Have your FA's always seemed flat, or have they gotten gradually worse? Are you sure it's a contrast issue and not an exposure issue? (could be machine related)
How much dye are you injecting?
Do you have a service contract with your vendor? (you could always call in the pros)
Either way, I would first check the contrast setting on your capture software. We use Merge (OIS) and there is a radio button on the right side of the screen that sets contrast... I believe ours is set on 5 or 6. That may be a good place to start.
I'm sure we'll see more ideas from the group...
Gary

Thank you-- Gary and Tim for your speedy response.

The low contrast issue supposedly has been going on around one year, unsure if it was gradual because there have been 3 different photographers during that time. Makes it hard to tell if it was gradual decrease or dealing with a learning curve. The low contrast is noticed on the camera and all monitors, it is not as bad on a 20 year old(employee) with no pathology, as expected, but the contrast still not where it should be with a willing person and no media issues.

We are injecting 5 cc of 10% AK- Fluor.

We do have a service contract, they say this camera should not need filters replaced for the life of the camera? Whats a camera life?:)

We had an extensive service last week, and were told the flash tube needs replaced. That will happen this Wednesday. Will try your suggestions and wait for Wednesday to see if issue improves. I will keep you informed. Thanks for your time!

Tue, 8 Jan 2013 14:34:58 GMT

Yes, Alyce, please let us know how things look after the tube replacement....

Gary

Tue, 8 Jan 2013 16:04:03 GMT

If the flash tube is compromised, it could indirectly effect contrast if things are slightly underexposed. When you have to bump up the gain or ISO to compensate for that it can reduce contrast. How do your control photos (baseline image through exciter & barrier without any dye) look? You might want to take a few control photos of a target or sheet of paper at different exposures, before & after flash tube replacement to see if there's a difference.

Tue, 8 Jan 2013 16:09:42 GMT

Good suggestion Tim.

I think it might be a combination of both poor output of an older flash tube and possible degradation of the exciter/barrier filters.

Although these filters are supposed to last for many (10+?) years I have seen them fail in as few as 5 years. It all depends on your sytem and frequency of use.

The control images Tim referred to will be a good indicator of the efficacy of the filter set.

Good luck and let us know what you find out.

bob

Exciter/Barrier Filters

Mon, 11 Feb 2013 14:42:45 GMT

Wanted to update you.....replacing the flash tube did absolutely nothing. Replacing the exciter and barrier filters made a world of difference. Thanks for your support!

Alyce

Mon, 11 Feb 2013 23:59:49 GMT

Thanks for the update. It was an interesting problem& its good to know the resolution.

RE:

Tue, 12 Feb 2013 19:14:36 GMT

T. Bennett said:
Thanks for the update. It was an interesting problem& its good to know the resolution.

Alyce,

Thank you for the update.... although now I'm getting the urge to replace my filters! Where did I put that Zeiss phone number.......?

Gary

ps/Glad to see you are still with us, Tim!