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-   -   Tri-focals ? (https://www.pprune.org/medical-health/146989-tri-focals.html)

ooizcalling 3rd Oct 2004 11:00

Tri-focals ?
 
Having finally succumbed to the requirement of using glasses not so much for long distance vision although I'm told a small correction was required but mainly for close-up stuff like reading Jepp charts at night etc, I chose the variable 'Varilux' type lens and after a period of getting used to it now cant get along without them ... Dam !

However, the overhead panel is a bit of a problem. Being closer to you, you need to use the 'close-up' part which is at the bottom of the lens , meaning that you have to tilt your head back to the point that it starts to 'crick' your neck, just to get the panel in focus.

Has anyone got a solution to this problem. I can't imagine having a second 'close-up' lens at the top of the glasses as well as the bottom but maybe ......

Any advice please !

taildrag 12th Oct 2004 02:47

There are a myriad of trifocal lens types on the market. I use a Varilux type myself. With proper fit, one can see all three distances in a natural manner. Still doesn't help overhead.

I found if one gets his prescription fitted "low," i.e., so the spectacles can be worn low on the nose, one can look at the overhead panel over the tops of the spectacles, without another "add" (what optometrists call the lens inserts observed in bi-or tri-focals) on the top of the lens.

There were some spectacles which did indeed have another "add" on top. They were jokingly called "Airbus lenses," since apparently the need for them in pilots was realized by the introduction of the Airbus into service.

E-mail me at [email protected], and I'll send you information about the several types of trifocal lense options.

Pilots have to see three distances-infinity (out the windscreen), a middle distance (the instrument panel), and "near,"(usually the approach plate holder, but now, vexingly, also the overhead).

The USAF school of medicine kept measurements for the three distances for each of their aircraft types at one time. So did Air Canada, I believe.

Now, if you didn't have to try to fly the sim with a full-face smoke mask, life would be a lot easier!


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