Dear Ani,

The eye is not filled with silicon.

The refractive index of the eye is about 1.33.

The APPROXIMATE power of the lens of the eye is
about 10 diopters.

The total power of the eye is about 60 diopters.

Otis

Dear Ani,

The eye is not filled with silicon.

The refractive index of the eye is about 1.33.

The APPROXIMATE power of the lens of the eye is
about 10 diopters.

The total power of the eye is about 60 diopters.

Otis

ani schreef:

Look for Gullstrand's schematic eye.

Be aware of the differences in refraction index and the differences in
optical system build up.

Jan (normally Dutch spoken)

Dear Friend,

You have made an assumption.  That the natural eye is
filled with silicon.  This is not the case.

In general, when a lens is removed (catarack surgery), the
power of the eye is reduced by about 10 diopters.

The power of the eye is about 60 diopters (different with
different people), but the result of removing that
internal lens is the need of a +10 diopter plus
for clear focus AFTER the lens is removed.

These values are approximate.  Using ultra-sound
methods -- better judgment may be made of the
power of the internal lens -- and the necessary
repacement.

Otis

You would have to know the refractive index of the IOL for starters. And
your question may have no possible answer.

For example if you are using an IOL with the same index or less than
that of the silicone oil, the power would be infinitely large, as no
matter how strong it is in air, it will have a zero or negative power in
a medium of the same index (unless the eye were very long, as in high
myopia).

Assuming an IOL of higher index than the oil, you need to know the
corneal curvature and the axial length of the eye.  From that, ordinary
optical formulas will give you a power for the IOL, but remember you
must correct for the power in air if the IOL is to be specified as
measured in air.

Of course no matter what you do, according to otis, the eye will adapt
and emmetropize itself so long as you never put a minus lens in front of
it, so I guess it doesn't matter what you put in there...

Who needs a cornea or an IOL anyway, since the fundamental eye will
always fix itself if left alone through the mystery of dynamic nature?

w.stacy, o.d.

I mean was people who under go for silicon oil insertion in their for
prevent retinal detachment so If they want to go for catract Sx how to
calculate IOL power calculation in these patient. becoz For caculating
we need to hav an axial length so the we usually ultrasound for
caculation of axial length but here Refractive index differ so device
caculates worng axial length so how do u caculate an axial length
length ultimately how u calculate IOL power .............. that my
question......