Wettability and durability with the higher Dk/l materials are not as
good in theory, and my experience in general confirms that.

I typically use the lower Dk/L RGP materials, especially with low
power DW RGP wearers or thin designs, such as a Polycon II clone.

I am not a fan of Menicon Z material.  The hydrophilic coating wears
off too fast and it requires you use a special cleaner (Claris) that
is hard to find in stores.  Sure, you can use Boston or Lobob daily
cleaner on it, but then it becomes unwettable in a matter of 3 months.

Tried FP150, same thing.  It becomes unwettable rapidly and needs to
be kept meticulously clean or it becomes hydrophobic and unwettable.
Patients complained it would cloud up constantly.

I don't worry about Dk/L as much in RGP wearers as I do for SCL
wearers for a couple reasons (at least):

1.  A lot bigger number, both in absolute numbers and in percentages,
of my patients sleep in their SCLs vs their RGPs.
2.  RGPs move better than SCLs, have better tear circulation under the
lens and with their smaller OADs I have less patient hypoxia
complications.

IOW, RGP materials have certainly come a long way in their Dk/L, but
the performance of these higher Dk/L materials leaves a lot to be
desired still IMHO.

The holy grail of RGP materials is one that has high Dk/L but performs
like PMMA.

With the exception of KC lenses, there is no need for anything other
than XO for any patient. KC lenses need the structural rigidity of
something like ES or EO, but XO is so much higher in Dk, there is no
point in anything else (unless you use Menicon Z, which is a brilliant
material)

dr grant

In general, the higher the Dk/L of the material, the more stable the
lens will be at a particular center thickness.

Therefore *in general*, RGPs made out of ES can be made thinner than
EO which in turn can be made thinner than the XO.

There's more to it than that, but that, in essence answers your
question.

What's the difference in thickness of these three lens?