Cleaning the Objective Lens
If the objective lens on your fundus camera (the
lens closest to the patient) becomes dirty or smudged, you will
get artifacts on your films. These artifacts will be most visible
on myopic patients. They will be less noticeable on angiography than on fundus photos because the angiography filters often subtract the flare.
How to Identify a Dirty Objective Lens
Set your camera to the myopic ( " - " ) setting and the viewing illumination to maximum. Darken the room. When you look
through the eyepiece you will be able to focus directly on the
front of the objective lens. Smudges, tears and hairs will all
be easily visible.
Note: With the viewing light on maximum, you may also see excessive central flare through the eyepiece. If you do not see artifacts on your photos matching this flare, don't worry about it. (Some fundus cameras have alignment problems causing internal flare that IS apparent on the photos - call us if you suspect you have this problem)
How to Clean the Lens
- Clean only when you cannot blow off items on lens!
- Always wash hands thoroughly before cleaning lens.
- Use a clean "Sterile Cotton Ball", available at any drugstore. Be sure that the part of the ball you apply to the lens has not touched your fingers. (We no longer recommend using photographic lens tissue - it has been shown to scratch the coating on many models' objective lenses).
- Never use silicon-impregnated lens tissues or cloths. These only build up a film on the lens surface.
- For oily smudges (like tears and nose marks) use a manufacturer recommended solvent, usually methanol, acetone or a combination of the two.
- Use very light pressure; never rub. Use a circular motion from the center to the perimeter of the lens. Throw the cotton ball out after every pass! Otherwise you will merely put back what you removed.
- When all smears and smudges are gone, a bluish film or some fibers from the cotton may remain. The film can be removed by breathing on the lens until condensation forms, then gently wiping with a fresh ball. Do not wipe if your breath doesn't form condensation on the lens.
Fibers can be blown away, or gently flipped away with a new cotton
- Check your work through the eyepiece as before, at maximum illumination and normal illumination.
Give yourself time to clean the lens. Ten or more balls for one cleaning is not unreasonable. When using solvent, do not soak the ball, just moisten it. It is better to use several balls than to clean all spots with just one ball.
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