I thought this was informative
https://chadwickoptical.com/high-minus-options/
I thought this was informative
https://chadwickoptical.com/high-minus-options/
I like that.
I use the lens thickness calculator on this site quite often when a pt wants to know the thickness of a lens with a given frame & material:
http://opticampus.opti.vision/tools/thickness.php
Those are really cool lenses. I wish more digital labs put the effort into custom lenticularization like that. I'm sure it's a PIA to do and disruptive to a high volume production lab. But if it were available from my primary labs, instead of small unknown labs, and in premium lenses, instead of all house product, I would use these types a lot more often. Especially for high minus wrpa frames, I've done a handful through specialty labs and they look amazing.
Here are some other cool options.
http://epiclabsinc.com/
This formula is incomplete as it’s not considering lens final size. Also, percentages often misled.
Dr K this is an awesome tool to teach newbies. Thanks for this!
Ignore that. I'm talking about the lens forms.
It's a rough but valid estimate.Originally Posted by ChrisBowers
I understand that the cosmesis is better with the blended surface designs, but I would strongly recommend against using them due to poor tolerance compared to standard lenticulars.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
I've never done a blended lenticular. So...interesting you have that experience. It does seem weird to blend out a ridge. It seems it would cause a blur ring off center. Who knows what it could do to peripheral acuity? But I guess the minification is so much it could be like looking through a sleazy motel door peeper. It's a "field expander" of sorts.
(Note of interest: in Low Vision Clinic in the days of yore, we would actually have a door peeper to show patients with retinitis pigmentosa. They could hold it up as needed for a quick survey of the scene before walking into an open manhole a la Mr. Magoo. Of course, we never had any real patients.)
Well, while we're on the subject of high minus and edge thickness, I've come up with a couple of rules of thumb (That means: rough. That means: go ahead and argue your case):
1. If a VISIBLE minus lens edge exceeds 5mm, it's fugly.
a. that means a plastic eyewire gives you 3-4 mm of bonus
b. that means a semi-rimless or rimless is working against you
c. that means a 1-2 mm metal eyewire helps only a pinch. It's the "neutral state".
2. When doing edge thickness calculations, if the reduction in edge thickness is not greater than a millimeter, it's just not worth it. Two millimeters? Now we're talking.
a. it may be better to set this rule of thumb up as a percentage, such as "if it's not at least 20% thinner, fugedaboudit", but I haven't tested that theory.
Remember, as a general rule of thumb (a few exceptions), thinner lens materials are inferior optically. I always explain this to pts and explain the trade-off. I don't recommend thinner lenses unless there is a 2mm or greater reduction in edge thickness.
Some pts are hyper focused on thickness so I do whatever makes them happy even if it wouldn't be my personal choice.
As we all know, frame selection (A measurement, decentration, etc) plays a huge part in the outer edge thickness for high minus.
comments in red
Plastic eyewire:
Rimless:
Her hair at the BET awards was FABULOUS!!!
Seconded (though from your informative posts over the years, this is hardly a surprise!)
Blended lenticulars are something I have almost always failed to switch existing conventional lenticular wearers into, and I dread the day the labs stop making conventional lenticulars.
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