Finishing lenses for semi-rimless and drilled rimless frames presents a unique issue. As an Optician, you are caught between choosing to polish or not to polish your lens edges, but have you stopped to consider both of your choices?
Unpolished Lens Edge
Polished Lens Edge
A common school of thought is that if the edge of the lens will be exposed (as they would be with both semi-rimless and drilled rimless frames) you should choose to have those edges polished in order to enhance the aesthetic of the finished glasses.
By polishing the edges of these lenses you help to create the "invisible" look of lenses, as the edges seem to disappear when polished versus the chalky white unpolished edge that would otherwise be present if you chose not to have them polished. After all, why would you encourage your patient to enhance their vision with a superior anti-reflective coating which will help their lenses appear to be invisible only to pronounce the edges by leaving them unpolished?
Many patients who have polished edges for the first time report seeing "rainbows" around the edges of their glasses as well as being surprised by or seeing internal reflections while driving at night and being outdoors on sunny days. This can be incredibly distracting. Often times these patients return to their Opticians not knowing exactly what the problem is but knowing their glasses are driving them crazy!
Although it seems like a no-brainer that you would choose to use a polished edge because it looks better, when you look into the mechanics of how light behaves within lenses with a polished edge you might change your mind on selecting the polished edge.
HOW TO PROCEED
It is always a good idea to ask your patient some key questions prior to ordering edge polish. One of these questions would be "Have you had rimless or semi rimless glasses before?" And if so, "Were the edges polished?" Then of course, you would follow up with "Did you have any issues with rainbows or reflections that bothered you while wearing those lenses?" How your patient answers these questions will help you to decide weather or not to choose edge polish for them.
If your patient is a first time rimless or semi-rimless wearer and they are unsure of whether or not to proceed with the edge polish, discuss with them their the pros and cons of edge polish and get their input on how they wish to proceed.
Some patients wear lenses with polished edges and have no problems with them, and some patients wear lenses with polished edges and endure the problems because the aesthetic is better. So it is always best to discuss the options with your patient and decide if function or fashion is going to be most important to them.
Of course, always remember that the 'polished surface' can easily be made stain with an emery board when a rimless or semi-rimless lens has been ordered polished. Just be careful not to take too much off of the lens as you risk making the c-size (or circumference) of the lens smaller than intended. This could cause the lens to be too small to fit into your frame correctly. If in doubt, call your lab to see if they can help.