RGPs - I can see until it falls

Hello all, I'm trying RGPs for my first time. With two brands of lenses,
a few base curves and diameters, the "problem" is always the same: when
I blink the lens goes up and I see clearly, but after 1 second the lens
falls down and I see more obfuscated, like if there is one ghost image
overlapped to the main image.

It's not very evident and I can live with that. I lose... say 1/10 of
visual acuity when the lens drops.

Is this normal? The optician did not have a clue. He said BCs and
diameters seem to be correct.

 

Astigmatism? My personal variety allows the lenses to slide up and down
easily, giving me really excellent vision for about 1 second out of 60.
The vision isn't as good with the softies I ended up with, but they're
more reliable.

 

An RGP lens can refer to any lens made of any number of a group of rigid
plastic materials. It says nothing about the diameter, optical zone, base
curves and any number of variables which are important to lens
stabilization. Because of their specific eye anatomy, some patients will
exhibit a tendency for a corneal RGP to drop. However, there are certain
"tricks of the trade" that can be applied to minimize this phenomenon. In
fact, using a lens of about 14.0 millimeters in diameter, or 2.5
millimeters larger than the average corneal diameter, will result in
absolute centration of the lens virtually 100% of the time.

DrG

 

Tnx alot
I will wait and see

Seems like the visual acuity of the (spheric) soft lenses is almost the
same of RGP before it falls. When the RGP falls it's slightly worse,
like 1/10 less...

 

I only mentioned this to illustrate the point that lens design makes a
difference. However, I do agree with your fitter that tear exchange is
important, and that lens movement - in the y-axis or the z-axis (provided a
fenestration is present) is necessary to provide it.

Corneal lenses commonly move up and down with the blink, but hopefully
center instead of dropping too much.

DrG

 

I have tried with a quite larger diameter today at the optician's shop,
and the problem did not disappear.

Back home I have discovered that the problem only arises if the eyes are
quite closed (*) but if I force the eyes to stay wide open, there is no
obfuscation of vision when the lens drops.

(*) my upper eyelids stay usually very low, compared to other people's.
They are just a couple of millimeters above the pupil.

Probably the lower part of the lens lifts a bit when dropping, if the
upper eyelid is over the lens while the lens drops.

 

Come on over to the U.S. where somebody can fit you with a Macrolens or
equivalent. It will not rise, it will not drop, and it will be
comfortable.

DrG