Your opinions please
Rx as follows: OD +1.50-.75x078 .75 prism down
OS plano-.50x087 .75 prism up
+2.00 add in a round seg 24mm clear cr-39
remade the left lens twice now and getting the same ghost image from direct light sources. There is no similar image on the OD lens. How can I get rid of this ghost without calling that short pudgy gal from Poltergeist?:bbg:
Trial frame to see if it's replicable.
maybe..................
maybe there is a real ghost in the prism who does not exist in the trial lens.
And if it is visible in the trial frame?? What then? I've seen this kind of thing before, always in lenses with low powers and not necessarily with prism. Never brought it "To the Board" before though. Don't think I've ever really resolved the problem although we have used A/R coat to minimize the effect. I'd rather you guys help me solve the puzzle.
I'm ready to grind a pair of lenses this time. I was thinking of modifying the prism amounts but leave the requested imbalnce intact.
Last edited by FVCCHRIS; 11-12-2008 at 12:36 PM. Reason: content added
To differentiate a lens issue from uncorrected astigmatism or any other organic issue.
Can you see the problem yourself?
The glasses are in hand and a ghost is in the house(lens):drop:
Originally Posted by FVCCHRIS
Your opinions please
Rx as follows: OD +1.50-.75x078 .75 prism down
OS plano-.50x087 .75 prism up
+2.00 add in a round seg 24mm clear cr-39
remade the left lens twice now and getting the same ghost image from direct light sources. There is no similar image on the OD lens. How can I get rid of this ghost without calling that short pudgy gal from Poltergeist?:bbg:
What is the base curve and material? Their are a few different ghost images that can present themselves, all would be reduced with an AR coating, also a change to the base curve could help, if the catoptric power and the patients dioptric power are close you can get a clear and defined ghost image, you don't want to change the patients dioptric power, so your left with the alternative of changing the catoptric power.
Send me an e-mail and I'll send you some stuff on ghost images.
Possible solutions to correct Ghost images:They may not all apply but sometimes a combination of techniques will help.
- Lighten tint
- Apply AR
- Lower Index material
- Change Base Curve (or go from aspheric to spherical or vice versa)
- Adjust Vertex Distance
- Reduce reflections from the face (reduce oily skin causing reflections)
- Smaller A size
- Apply Face Form Wrap to frames.
Last edited by HarryChiling; 11-12-2008 at 01:48 PM.
AR seems easiest.
Second would be cutting it on an 8-base. Agree?
Yep there are two key factors to eliminating ghost images
AR is going to reduce the intensity of light reflected and changing the base curve will blur the reflected image hopefully enough where the image is not recognizable to the eye. Ar is not only he easiest but could help avoid creating another issue with a change of curves.
- reduction of intensity
- and causing the image to blur
very helpful thread
Have you looked at it through slit lamp to make sure surface has been adequately polished ? I had a similar problem although with a lot stronger Rx, due to surface left with rough microscopic grind marks.
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