Two years ago I didn’t entertain any inkling that I would end up considering my eyeglasses in the same way I considered my range of clothes, that is, items appropriate to the season or occasion. My education began with Rob Sands’ entertaining and informative youtube videos on various topics, from designers to lens manufacturers, to tints and coatings. By the time I settled in with Kashan I was able to be very specific with the questions I needed to ask in order to end up with a finished product that satisfied us both.
A recent example:
I brought my new pair of Ahlem “Rue de Turenne” frames to Kashan to glaze with my usual Zeiss Smartlife Superb progressive lenses (with a 50% Sweet Violet tint). When they were delivered, there was something strange about the quality of vision through them. They had exactly the same prescription as my other everyday pairs, but the reading area was pinched, too narrow and off-centre. Kashan immediately jumped into action.
He arranged a conference call for me that included a rep from Zeiss. I described the out of kilter phenomenon I was experiencing and over the next hour, Kashan, Josh and I worked through to a likely solution. I learned an optical term of art that was new to me: corridor. The corridor can be short or long (there are numerical designations for the minute differences in their design), but it essentially amounts to this: the corridor is the transitional zone on a varifocal or progressive lens that connects distance vision at the top to reading vision at the bottom, in other words, it’s the clear mid-range focus.
Between a short corridor and long corridor, there’s a trade-off. A short corridor gets you to the near vision area on the lens quicker, i.e., a flick of the eye instead of a tilt of the head, and the longer corridor will give you a wider mid-range but you’ll need to look further down in order to read. Kahan and Josh’s detective work resulted in a solution. Most probably on account of the shape of the Reu de Turenne’s lens, the corridor measurement that worked perfectly well on my other glasses didn’t work at all on these. Kashan tried reglazing them with a wider corridor and voilà, sharper reading vision restored.
During any conversation about glazing or reglazing, be sure to ask about every aspect of the focusing power of the lens you choose. This might include the way in which each visual area — distance, middle and near — are “mapped” onto the lens. I’ve had good luck with Hoya, better luck with Zeiss, and no luck at all (given my particular prescription) with Essilor. (I remember starting my experience of progressive lenses about 35 years ago with Essilor, and they took some getting used to after years of single vision (distance) glasses, but they were fine in the end. The technologies have evolved quite a bit since then, for every manufacturer, though I’ve found Zeiss the easiest to get used to when my prescription changes.)
Here are a few other areas to discuss with your dispensing optician:
You’ll also want to know the difference in the types of lens designs the manufacturer offers, so ask for info that compares and contrasts different manufacturer’s designs. I can only speak about Zeiss, as they’ve supplied the lenses for all of my pairs, and a visit to their Web site is pretty informative. For prescription lenses the most reasonable choice for me has been the SmartLife Superb, which is an all-rounder suited to quick changes in focus from distance to your digital device and back again.
Your optician will help you decide on the best “index”, another optical term of art that refers to the thinness of the lens material — 1.5 being the thickest and (relative to the others) heaviest, up to 1.7, the lightest and thinnest. The strength of your prescription will be a factor in your decision, as will the type of frame you choose. For instance, a thin wire frame for a high prescription will dictate the thinnest material so that your nose bridge doesn’t collapse under the weight.
Frame shape. We’ve all done it — admired a piece of clothing that looks great on somebody else but terrible on us. Same thing with glasses. Now, I have a small face, so I’ve had to learn to keep the width of my frames under 140 mm. This (thank goodness for my wallet’s sake) excludes 95% of JM Mage. So a pro tip: you can admire the style of a frame you find online or see on a friend or celeb, or celeb friend, but either make sure you can return it if it turns out not to fit you because it’s too big or too small, or find a store somewhere you can try it on. And don’t be swayed by luxury price tags. There are brands like Mapi and Moscot that sell beautiful glasses at a price that won’t max out your credit card.