On Sat, 18 Nov 2006 10:37:49 -0800, Jim Stewart
wrote:

skyfish wrote:

I want to get current on my VFR Single Engine Land license but my eyes
are not what they used to be. The strength I need for good far vision
makes it so I can't read charts in the cockpit without taking them off.

I figured I would try a progressive lens because I thought it would
eliminate the extra task of taking my glasses off to look at a chart
(less work load is good right?), but I'm concerned about a few things:


Some excellent comments have been made and in particular by 'Bushy
Pete'.
When I first went for the PPL medical I had to wear glasses for the
first time. I had almost mastered landing but with glasses it put me
back about 3-4 days until I got used to them!

I chose progressives (varifocal) with photochromics which after a few
days I got used to them. What I found at this time was I'd had
astigmatism for 48 years without knowing.

About a year later I needed 2 pair of glasses to comply with UK
requirements for a spare and was advised by the UK AME (also a pilot)
that I should use bifocals as they had less distortion.

I still sometimes use them, though that prescription is from some
years ago, but mostly I continue with progressives. I changed optician
and explained in detail the need to read maps, see the panel and
distance with maximum clarity at the sides. I also said I don't want
to tilt my head too high to read close up but still want to see the
PC. Oh! yes and I wanted anti-reflection, maximum darkness in sunlight
and maximum transmission of light at night - otherwise just a pair of
glasses?

About 2 years ago a new lens was on the market which allowed me to
tilt my head only slightly as the vertical range of focus changed
quickly from distance to close-up. The prescription was actually
backed off slightly to that from 2 years previously and I achieved
everything almost perfectly.

What I have learned over the years is photo gray can be made to from
about 2% to 95% transmission compared to normal photochromics only
around 20% to 80% so not as good for night flight.

With progressives the stronger the prescription the narrower the field
of view. If you imagine the clarity is best in the middle of a 'V'
shape the stronger the prescription the closer the sides of the 'V'.

Bi-focals have good lateral clarity but make sure the change does not
occur in the middle of the panel.

In conclusion I almost always use progressives except perhaps at night
then I return to the bi-focals but they were set with the line right
in the middle of the panel. A real pain but I can still see the panel
with either part of the lens.