Try to steer clear of photochromatic polycarbonate flat-top bifocal lenses in a semi-rimless frame.
Transitions brand of photochromatic lenses are not available in polycarbonate flat-top bifocals. Therefore, your lab will place the patient into a “generic” brand of photochromatic. This generic is made using a laminate procedure, unlike brand name Transitions. Due to the need to cut a groove in the lens for semi-rimless frames, the groove will often causes splitting of the laminate layers. Within a year this will cause a white haze to form around the periphery of the lens, especially around the groove, as the photochromatic layers split. here is what you need to know…
You have one of three options to prevent this from happening and keep your patients happy…
- Place the patient into a Trivex material lens which IS available in Transitions brand flat-top bifocal (like polycarbonate, it is very light, thin and impact resistant). This is our preferred and simplest solution.
- Try to convince the patient to go into a progressive lens. Progressives are available in a Transitions brand polycarbonate.
- Try to convince your patient to get a full rim or fully rimless frame (These will not require the groove to be cut as semi-rimless frames require). Be aware that in fully rimless frames, polycarbonate is likely to create starburst cracking around the drill mount. In these cases we recommend Trivex.
The maker of these generic laminate photochromatics are apparently aware of the issue and are working on it, but we are still seeing the problem frequently. Therefore, it is our recommendation for the near future to avoid whenever possible the Photochromatic/Polycarbonate/Flat-top bifocal/Semi-rimless frame combination. Switching to Trivex is our recommended solution.
Read our previous post here.