Jacobus Boshoff on why a good optical dispenser sometimes needs to dish out the harsh truth, and why frame choice starts with a prescription.
Picture this: Mrs Fancypants, a new patient at your practice, arrives driving a very flash car. She sports a diamond the size of a cricket ball on a ring and an even larger one on a gold chain around her neck.
She trots in 10 minutes early for her eye check with the optometrist. Eager to save time, you decide to browse frames beforehand, skilfully guiding her towards the latest designer frames fresh from France. She falls in love with a nice large inline frame and you hand her off to your optometrist, congratulating yourself on your efficiency.
The optometrist returns Mrs Fancypants to you. Her near script is R +3.50/-0.25×180 Prism 4 Base In and L +3.00/-0.50×5 Prism 4 Base In… oops.
“Mrs. Fancypants, the frame we selected won’t work with your prescription…” Egg. All over. Your face. Now you have to explain why a 56-16 metal inline frame she LOVES won’t accommodate her reading glasses, and start from scratch.
Mrs Fancypants is unhappy. The shell frame that fits her nose and prescription perfectly is not the ultralight, flexible designer frame she fell in love with.
This is why dispensers are taught in the Certificate IV in Optical Dispensing that frame selection always starts with an optical prescription. The frame’s job is to position the lens correctly for optimal vision. It must fit well on the nose, match the face width, and have appropriate temple length-to-bend (too long, we can adjust; too short, like a bad haircut, is just too short).
Dispensers need to explain optical reasoning behind our frame recommendations in layman’s terms. “Mrs Fancypants, that frame looks fantastic, and I’m sure they’re featherlight, but with your prismatic reading prescription, the lenses would be horribly thick nasally. The prism, which helps your eyes focus without strain, creates a wedge on the inside of the lens. Metal inline frames also require a minimum edge thickness. Even with high-index lenses, the result would be less than ideal.”
See, it’s all about her and her needs.
How about we start the frame selection with her prescription in hand and look like rock stars from the get-go?
A rock star optical dispenser considers the following:
• Intended use/lens type: Single vision or anti-fatigue, office, bifocal, trifocal, or progressive? Some lenses require a minimum frame depth. Office lenses, in particular, do well with a bit more depth to get those long-corridor marvels space to do their magic. The same applies for progressives to a certain extent, although we have short-corridor options in most progressive lens designs.
• Prescription specifics: High spherical, cylindrical, or add powers? Cylinder axis direction? Remember power crosses! Prism? Where will the prism thickness sit? Try to visualise what the intended lens will look like, and where problematic edge thickness may occur. Frame shape and size can have a huge impact on lens thickness and weight.
• Frame evaluation: Front and side views. Pantoscopic tilt should ideally be negative 6-9 degrees. Positive panto (bottom angling away) is generally a no-no, even with high-end, digitally enhanced lenses. Back vertex distance (BVD): will eyelashes touch the frame? Is the BVD so large that the prescription needs correction? High BVDs work against field of view – keep this in mind for progressive lens corridors that may be compromised. Sometimes nose-pad adjustments nip the issue in the bud, and sometimes you have to change to another frame.
Red flags: Very curved frames and oversized frames. High prescriptions in curved frames can induce unwanted prism. Oversized frames often make finding suitable lens blanks difficult, especially for reading glasses. Remember the minimum uncut size formula? Check the Optical Dispensers Australia website’s calculators (https://www.odamembers.com.au/calculators).
I’ll stop my diatribe here. I’m sure you get the gist and can think of many more issues with improper frame selection from your own hard-earned experience.
In the meantime I have to get ready for Mr Dinnerplate, who is coming in shortly.
He loves oversized frames for his progressives. They look great and fit well, but finding large enough lens blanks is a headache. I have sourced one supplier with progressives lens blanks that fit Mr Dinnerplate’s previous set of glasses. But if he wants reading glasses, I can already hear myself saying, “No, you can’t have that frame!”
About the author: Jacobus Boshoff is a qualified optical dispenser and independent practice co-owner in Forster, a town in NSW’s Mid North Coast region. He is a member of Optical Dispensers Australia, serving on its advisory board.
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