Tom Davies having a polarised lens rant (Diary of a Spectacle Designer, Optician 17.05.24) cannot be allowed to go unanswered. After all, he is a highly successful frame designer although, as he himself admits, that doesn’t make him an ophthalmic lens expert.
UK supply optics has always been made up of fascinating partisan tribes, which makes it all the more enjoyable to spend a lifetime in the sector. Frame makers rarely mix with lens makers, even in the few companies that cover both disciplines. It’s no different within that smaller sphere of a prescription house where lens surfacers and glazers often remain worlds apart, both socially and physically.
This was particularly true historically, when lighter glazing machinery was usually top floor or front of house, while heavier lens surfacing plant was confined to the background floor or an even lower floor if one was available (code for cellar). The traditional salutation between lens surfacing staff and spectacle frame glazers was ever ‘we make them, you break them’.
There cannot be many of us now around who remember Lenses Ltd in Farringdon Road, where its lens surfacing shop was some steps into what was almost an underground dungeon. I don’t recall it having any windows, only a back door out onto Bakers Place. Lens working was always a tough, physical, dirty job and thus somewhat antisocial. I recall my mother used to relate that on the evening Islington bus home the conductors would not allow lens workers to board because their clothes were covered with red rouge (lens polish), which got onto other travellers, so they had to walk home.
Tom can be excused from not being totally au fait with lenses, especially polarised lenses, which occupy the top of the specialist sun lens tree. We will avoid a technical summary about reflected light and all that, but note only a sufficiently dark polarising layer works to full polarising efficiency (ie you just cannot have clear polarising lenses).
Tom mentions his team, who likely know even less than he does about lenses given their talk about throwing a pair of polarised lenses into frames as upmarket demo lenses. That’s serious stuff, moving the dial from CE-CA marked spectacle frames into the realm of personal protective equipment (PPE). Yes, sunglass standards fall under PPE, with all its tighter regulation.
But back to Tom, I wonder which polarised lenses he tried. If someone on your staff just gave you a new frame into which, might we say, an economical pair of polarised just popped in, then it could be they were not exactly high efficiency polarised lenses. Tom’s own wording shows he is aware of the need to maintain high axis integrity when fitting polarised lenses into frames.
Any similar comments from clients should have the lens technician reaching for their polarised lens alignment tester. It will quickly expose any technical issues of off axis or over-glazing.
Tom remarked he has tested a number of sunspecs on his roof top and couldn’t note a significant difference between what I imagine were tinted acetate sun lenses and polarised planos.
Somehow, I suspect Tom’s all white roof space isn’t going to be such a brilliant test background for polarised evaluation. White paint specks, one assumes emulsion rather than gloss, are going to have multi-directional alignments. Polarised lenses only really work well dealing with horizontally reflected light.
So, Tom, in the style of your own often challenging words, do send along a frame and your Rx script and we will make you up a proper pair of polarising glasses so you can judge the fantastic visual differences that polarised Rx lenses can deliver.
There are so many polarising variants available today, including those driven by photochromic polarising technology, which only polarise when changing to dark, and I mean completely dark. All this can put even lens experts into a spin with the subtle differences between photo-polarised and traditional polarising boosted with added photochromic elements.
Polarising has a few downsides; should you drive an ‘antique car’ with toughened glass, their heat toughening spots will show up, which is not a problem with laminated glass screens. Also, as Tom noted, in modern cars with digital screens some can appear permanently dark, which some might say is a good thing, except when this happens to airline pilots where it would definitely not be a good thing. Flight decks need to avoid polarising lenses.
But away from screen technology, out there in the natural world, colours of our wondrous green countryside look fantastic.
So why have polarising lenses anyway? My own polarised Rx (Younger Drivewear) frames never leave the car. This is in remembrance of a sunny spring driving day when in came a sharp shower that almost instantly turned the motorway to a mirror surface with lorries decanting sheets of fine spray into a wall of non-vision. Those Younger Drivewear polarising lenses at that moment were essential for safety.
So, defeating horizontal glare reflections off wet road surfaces, water, sailing, fishing rendering remarkable countryside colour and generally removing that UV washout is polarising forte.
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Frank Norville, Managing director at Ellivron Optical