|Following a logical frame adjustment order makes adjusting quick and efficient.|
Each issue, Tech Tips will explore some interesting aspect of optical technology. This month we look at the order of frame adjustments.
Follow this adjustment order and adjusting will become more efficient.
There’s an order you should follow when you make frame adjustments because some adjustments affect others:
- Skewing of the eyewires
- Coplanar alignment (X-ing of the eyewires)
- Face form tilt (wrap)
- Endpiece symmetry
- Temple spread
- Temple shaft adjustment (curving is necessary)
- Vertex distance (equal distance from the eyes)
- Pantoscopic tilt
- Temple earpiece adjustment
If you don’t follow this order, you’ll find yourself having to make the same adjustments over and over again because you’ve knocked one or more out of alignment. That’s not very efficient. Notice that the first four adjustments are performed on the frame’s front. That’s because any alteration of the front’s alignment affects the alignment of the temples. Until you have the front alignment settled, don’t perform any temple adjustments unless the temples are too close together or widespread. In those cases, adjust them just a bit so the frame doesn’t fall off the face or press against the temples severely.
A skewed bridge occurs rarely, usually when the frame has been handled roughly. Fortunately, you won’t need to do much of this but it happens. For plastic frames, warn the bridge area, wrap one hand around each eyewear, and push the bridge into alignment. For metal frames, use the appropriate adjusting tools.
Coplanar occurs when the eyewires lay in the same plane. You know you have the adjustment correctly when you look down on the frame from above and see the upper eyewire overlap the lower one for both eyes simultaneously. You make this adjustment by rotating the eyewires at the bridge. You’ll also adjust the bridge to adjust face form (wrap) alignment. You can’t do much with curving the frame’s eyewires at this point because they will take the shape of the lenses. The last front adjustment is to ensure the endpieces are symmetrical. This is because they affect temple angling.
Now that the frame front is aligned, you’ll start on the temples. At this point, it’s wise to adjust the temple spread. The idea is to establish a comfortable but secure fit for the patient. The usual way to perform this adjustment is by manipulating the endpieces. Opticians often adjust the front section of the temple to do this but that’s not a good idea as it weakens that portion of the temple. You’ll probably find that you will curve the temple shafts if needed while you’re making this adjustment since that has a bearing on temple spread. Temple spread also has a bearing on vertex distance so you’ll be looking for this too as you make the temple spread adjustment in order to have equal distances from each eye (in most cases).
Pantoscopic tilt is done next and is performed by angling the temples. Again, this should be done by adjusting the endpieces but many opticians twist the temple at the hinges to do this. Adjusting like this weakens the hinge. Yes, I know that some contemporary frames make it very difficult to avoid doing this. That’s an issue you need to take up with your frame buyer. If a frame can’t be adjusted properly, do you really need to carry it?
The last adjustment is fitting the temples behind the ears. This takes some skill because the temple earpiece should fit closely but comfortably over and behind the ear. For skull temples, only about an inch comes in contact with the crease between the ear and the head while all but the final portion of the temple’s earpiece fits flush to the head. Practice will make perfect with this adjustment.
Ed De Gennaro is Director, Professional Content of First Vision Media Group.