Frame Adjustment, Repair, and Dispensing
Bench alignment
Four-point alignment means the frame front is straight, temples are parallel to each other and perpendicular to the front, and both temples touch a flat surface simultaneously. Check x-ing (crossed temples), vertex distance (commonly 10–14 mm, near 12), pantoscopic tilt (about 8–12°), face form or wrap (about 5°), and the frame front's horizontal and vertical alignment.
Fitting sequence
Adjust nose pads so weight is distributed on the nasal slopes, set the temple bend to follow the skull and rest above the ear, correct temple length, then refine tilt and wrap. Adjust metal with pliers placed at a supported point; use a frame warmer for zyl and heat only until pliable, since overheating clouds or crazes plastic.
Repairs
Identify whether the break is in the eyewire, hinge, endpiece, bridge, or temple. Hinge repair requires matching barrel size and orientation; reassemble with correct screw length and a screw-retaining compound where appropriate.
Traps
- Changing pantoscopic tilt without considering induced prism and effective power.
- Over-bending temples so the frame slides down the nose.
- Treating a cracked drill hole in a rimless lens as repairable when the lens needs replacement.
Worked example
A patient reports blurred distance vision and a frame that sits low. Before remaking lenses, restore vertex distance and pantoscopic tilt to nominal, since both shift effective power and optical center height. Recheck acuity on the adjusted frame first.