difference between hi index and thin lens?

difference between hi index and thin lens?

precription card has both options - hi index is ticked?

 

As you increase the index of refraction, a lens of a given power and
diameter will decrease in thickness. High index lenses are a benefit in
higher power prescriptions, especially minus powers.

So, hi index/thin imply the same thing.

But you can also make a lens of a given power and diameter thinner by
decreasing the center thickness while maintaining the same curves. At a
certain point, the "thinness" of the center causes the lens to break.

A thinner designed lens of a lower index is better suited for lower
power lenses.

--LB

--
Dr. Larry Bickford, O.D.
Family Practice Eye Health & Vision Care

The Eyecare Connection
http://www.eyecarecontacts.com
larrydoc at eye-care-contacts dot com (remove -)

 

As you increase the index of refraction, a lens of a given power and

So a "thin and lite lens" 1.6 for a -5.5 precription is ok then?

 

Dear (oh dear) Robert,

Some of us DO write sensible recommendations below the optical Rx, often
based on patient's priorities. So it's the "almost always ignore" part
that got to me. I know, sometimes you must see some pretty silly stuff
written down there ;-)

Of course you pragmatic, ethical and knowledgeable opticians---you know
that subset of your profession--- can certainly help to zero in on the
best spectacle optics for the patient's needs.

Best regards,

LB