Talk:Adjustable-focus eyeglasses

Started Discussion Page 30 Sept 2009
Okay, so it's 30 Sept 2009. This page has been in existence for over a year and still no discussion entries?! Something's weird here. Talk! for cryin' out loud! :-)

71.126.231.12 (talk) 21:25, 30 September 2009 (UTC)

Attempted to fix style
I made a hack at fixing up the unencyclopedic and non-neutral style. Removed background info when it was distracting. This is an article about the lenses, not a place to lecture about presbyopia. Although, a short background section with links to articles about refractive errors, presbyopia (which isn't really a refractive error), etc. might be good.

71.126.231.12 (talk) 22:28, 30 September 2009 (UTC)

Still needs work, tags still apply
I made a bunch of fixes to address the tag complaints, but I think the tags still apply. More work is needed.

71.126.231.12 (talk) 22:51, 30 September 2009 (UTC)

What's with the reference list?
The reference list is so long compared to the tiny article that I'm skeptical of it. It looks like someone might have just copied a list of references regarding the subject regardless of particular applicability. I've done that myself, i.e. I've listed hard-to-find references without specific inline citations just to help get the complaining irrationally-rabid-citationists off my back. But, I've made only one or two non-specific possibly-not-applicable references. I am suspicious that there may be many non-applicable references here.

The article basically says "Hey, these things are adjustable, how cool is that? There are two ways this done, way A and way B." On the side, it seems to explain presbyopia (and neglect hyperopia). It implies that they are only good for "positive" prescriptions, i.e. concave lenses, but I'm not sure this is true. This really isn't much, although it's probably all that  needs to be said. That said, the reference list looks like was written to support a scientific paper. It looks "outta control".

71.126.231.12 (talk) 04:28, 1 October 2009 (UTC)

Adaptive optics, or active optics?
Under "See aldo", adaptive optics is suggested as an alternative for adjustable focusing.

However, I presume active optics is meant here. These two, though often intermixed, are not the same. Adaptive optics is used e.g. in telescopes to compensate for wavefront distortion, e.g. due to atmospheric turbulence. Adaptive optics corrects with typical reaction times of terns of milliseconds, which is unnecessarily fast for eyeglass use, and therefore probably too expensive.

Active optics, on the other hand, is used to correct a telescope mirror's shape when it is deformed by its own weight when the mirror is moved to follow a star. I can imagine that something like this latter technique may also be used to "deform" an eyeglass to adjust for near-field use (reading) in case of presbyopia. Typical reaction times here are in the order of a few seconds.

HHahn (Talk)  15:49, 26 July 2010 (UTC)


 * No reactions so far? HHahn (Talk)  09:42, 12 April 2011 (UTC)

What is ADD tracking?!?
The article has this sentence:

"A tiny mechanism, actuated by the slider, simultaneously controls both flexible lenses to assure appropriate ADD[clarification needed] tracking in both eyes."

So...I've been trying to clarify what "ADD tracking" is by doing searches on the internet. I've had no luck, for the following reasons:

- "Add" is a very common word, and putting it in capitals or putting periods after the letters does not prevent search engines from seeing "ADD" (the acronym) as the common word "add".

- There are apparently some vision problems commonly associated with Attention Deficit Disorder,

- Many websites that allow you place online orders will also allow you to "add tracking" so that you can keep track of where your package is...

And so on. My attempts to guess what ADD might be an acronym for have been fruitless, too. Searches on the subject of binocular vision have gained me nothing, except maybe a little trivial knowledge of some of the fringe stuff going on with robotics.

'There has to be an optometrist out there who knows what "ADD tracking" is. If so, please insert an explanation, either in the article or on this talk page.' Ormewood (talk) 14:40, 20 August 2010 (UTC)

OK...I found the following in the eyeglass prescription article in Wikipedia:

"N.V. is an abbreviation for "near vision". This may represent a single-vision lens prescription to improve near work, or the reading portion of a bifocal lens. Some prescription forms use "ADD" in place of "N.V." with a single box to indicate the additional refractive power to be added to the spherical of each eye."

Based on that, I'm going to replace the phrase "ADD tracking" with "near vision tracking". If anyone has any objections or clarification then either correct my error yourself or point out what I did wrong on the talk page.Ormewood (talk) 22:42, 20 August 2010 (UTC)


 * My guess is that "add" stands for "addition". That is the term used for the extra ("added") lens power in the lower (reading) part of amn eyeglass. The three capital letters look strange indeed, wrongly suggesting it to be an acronym.
 * But what is "addition tracking"? Another guess: trying to determine the distance to the object viewed, in order to automatically set the correct addition needed fot that distance? If this is right, it is similar to an automatically focusing camera.
 * Sorry that all this is nothing more that a guess...
 * HHahn (Talk)  09:49, 12 April 2011 (UTC)

How old is Joshua Silver's idea of adjustbale eyeglasses?
The article does not seem to be very clear on how old Joshua Silver's idea of adjustable-focus eyeglasses is. When I was at secondary school (must have been 1963 or so), our physics teacher demonstrated the working of the eye's lens with the aid of a constuction consisting of two thin cellophane sheets, kept apart by a spacer ring a few millimetres thick and approx. 50 mm inner diametre, and this complete set clamped between to brass rings. At the bottom, the spacer ring had a small hole, into which a piece of plastic tube about half a metre long was glued. The other end of the tube was glued into the bottom of a small vessel containing a clear liquid (I seem to remember that it was benzene). When a small plug at the upper side of the construction was opened, the air flowed out and the system was filled with benzene. The two cellophane sheets with the benzene in between got curved by the hydrostatic pressure in the benzene. So it worked as a lens. The lens power could be controlled by moving the benzene vessel up and down, changing the hydrostatic pressure in the benzene and as a consequence the curvature of the cellophane sheets.

As the systems was designed as a classroom demonstration, its size was far too big for a real eyeglass. But it obviously demonstrated the same principle as is used by Joshua Silver. It may have been a standard classroom demonstration, but we were told that our school lab assistant himself had built it.

So I am just wondering how old this idea is...

HHahn (Talk)  20:12, 3 June 2011 (UTC)

Confused references, and unacknowledged prior art
The current ref. 2 refers to Martin Wright, but ref. 3 to Luiz Alvarez. According to https://opg.optica.org/oe/fulltext.cfm?uri=oe-25-24-29847&id=376946#ref10 Alvarez was awarded a US patent in 1964: "L.W. Alvarez, “Two-element variable-power spherical lens,” U.S. patent 3,305,294 (3 . December 1964)"... which significantly precedes Wright's 1978 patent. MarkMLl (talk) 20:13, 26 April 2023 (UTC)