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In our industry, you may find yourself in a variety of situations - dealing with the nicest patients to, of course, the dreaded unreasonable client. Everyone has heard stories about how patients who have strong prescriptions and rely heavily on their glasses often do not have a spare pair. This has made me wonder at their priorities. Their vision is critical to them because they can't see a thing without their glasses. Yet if they suffer a breakage they become very upset that their vision is compromised.
Unfortunately, there are those that do not even have one pair of glasses, even though they are functionally blind without them, because they simply lack the means to purchase them. Some of these people go their entire lives without glasses. This can sometimes cause the person without glasses to be vilified, or mistakenly classified as a special needs person.
I recently had an opportunity to help someone I've never met or seen, and probably never will, but nevertheless was compelled to do so. Sometimes you come across something that speaks loudly to your inner optician and it will not let you turn away.
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On the premier online community for eye care professionals, Optiboard.com, a thread was started seeking help for a student of a former coworker (now in Louisiana) of one of the members from Georgia. She was a very high myope, had no glasses at all to see with and was indeed classified as a special needs student. Her teacher told me this girl had been a discipline problem and was a very poor student. Since I was formerly a minus 15.00 before my cataract surgery, I have a strong affinity for these types of patients. So I volunteered to make the lenses for her if they could fit and measure the frame, and send it to me to make and mount the lenses. Her Rx was: OD -14.50 sphere and OS -17.50 sphere. Fortunately, they picked a frame with excellent fitting characteristics as far as not having any excessive decentration horizontally or vertically that would make the lenses even thicker than the prescription required. |
The lenses I chose for her involved a lot of time, but they produced a very nice result. A lot of people would have immediately thought of 1.67 or 1.74 index lenses for this high of a power, but that can produce such poor peripheral vision due to a low Abbe value for those lenses. CR-39 has an excellent Abbe value and will produce excellent crisp vision, but conventional processing of those will produce a very thick edge. So I used an old, little-known technique, where I started out with a +20 base single vision aspheric lenticular "poached egg" lens and turned it into a reverse saddleback myodisc.
With some help from the never-to-be-sufficiently-thanked Harry Chilinguerian, I arrived at some final lens calculations.
Front Curve Calculation
Since the front curves are going to be negligible in power, the thickness won't have a significant effect on the front curve power, so it's easier to use the lens maker’s equation:
Power = Front + Back
OD
-14.75 = Front + (-14.79)
Front = (-14.75) + 14.79
Front = + 0.04
OS
-17.50 = Front + (-16.64)
Front = (-17.50) + 16.64
Front = (-0.86)
*If I could make a recommendation to use the -19.00 as the back curve for the OS, it would allow you to have a complimenting plus front curve and reduce the amount of disparity in magnification as well as disparity in reflections: - Harry Chilinguerian
OS Back 1.498 = -19.00 * (0.49/0.53) = -19.00 * (-17.57)
OS
-17.50 = Front + (-17.57)
Front = (-17.50) + 17.57
Front = + 0.07
So I went with Harry’s recommendation of the -19.00 tool for the OS. Next came the grinding of the lenses. First I taped up the "back" side of the lenses and blocked them up so that the "front" curve was now going to be the new back side. I then ground the requisite curves until they nearly filled the bowl of the front aspheric curve, then fined and polished as normal. Then I taped up the now finished back side (formerly front side) of the lens and started grinding the new front side of the lens. Since there was very little leeway in thickness, I had to start grinding at a huge thickness and bring it down a small amount at a time. Eventually, the tool starts skimming the new front and when the new surface is completely ground, fining and polishing happens again. After polishing and inspecting, I sent the lenses off for Carat Advantage AR.
After getting the lenses back from AR, I was able to edge and mount the lenses, and they looked pretty good. I sent them off to Michelle Pelisier in Louisiana, the teacher and former optician and soon was rewarded with a photo of the girl wearing her new myodiscs. Seeing her seeing (and smiling) again really brought home to me how lives can be improved so greatly by something as seemingly simple as a pair of glasses.
Many thanks to the other Optiboarders who chipped in to help procure these glasses for this fine young lady. Thanks also go to Dr. John Henahan of Spectrum Eyewear in Atlanta, GA who also donated a pair of glasses. This was truly a multi-state operation with work done in WV, GA, PA, and LA, and donations from many more states.
And, since these worked out so well, we thought we'd go a step further and create a spare pair for her. This time I used a pair of 11.00 base 1.71 index lenses, and thanks to the higher index of refraction, she will have an expanded field of view through these new lenses. Having worn the 1.71 index myself, I thought this was a very viable material for her prescription. The Abbe is higher than any other ultra-high index lens. The procedure for manufacturing these was essentially the same as the CR-39 lenses, but with an obviously different set of curves. I also tinted the lenses lightly before sending off for AR, so the lenses should be a bit stealthier with fewer glittering reflections. I also used just a soft satin edge polish.
A few weeks after sending the glasses, I was told I had a phone call, and when I picked up the phone, a shy voice on the other end identified herself as the recipient of the new glasses. She told me she was very happy that she could now see and was excited to have her new pairs of glasses. Michelle told me that this student was now the smartest girl in her class and the discipline problems have gone away.
This is yet another example of how important children's eye care can be. Don't just ignore your children if they're griping about not seeing something - take them to your eye doctor!
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