by Karlen McLean, ABOC, NCLC
IMAGE COURTESY OF HILCO
Q We have a patient that needs a ptosis* crutch. Can you explain the steps we need to take to get the correct ptosis crutch for the patient and how to go about dispensing one? Also, can you only order a ptosis crutch on metal frames?
A First, contact the lab that will be providing the crutch to see if they have a preference as to which frame material the patient will select. Both metal and plastic (zyl) frames can be used, but with limitations.
All frames should be chosen so that the upper eyewire is in close proximity to the orbit. Frames with very large or small B measurements will not work.
PLASTICS: Plastic frames should be of quality acetate material and must have adequate thickness for the crutch to be riveted or embedded into the frame. Frame styles with thin eyewires and propionate type materials will not withstand the demands of sustaining the crutch in the correct position.
METALS: When choosing a metal frame, be certain to pick a frame with an excellent grade of base metal, but not titanium.
The crutch, usually a stainless steel wire, will be soldered onto the top eyewire. The frame must be of a sufficient dimension to bear the crutch and withstand the rigors of heating during the mounting procedure. Some newer alloys either cannot be soldered or break down under the extreme heat required for soldering.
Once the frame is selected, it should be adjusted properly to the individual's face. Then take a measurement to ascertain the depth of the crutch. This can be easily done using a distometer while the patient has their eyes closed.
Hold the distometer against the ocular side of the frame, in the middle of the upper eyewire. Then measure to the deepest point under the brow where the eyeball (covered with the closed lid) meets the over-hang of the brow.
To dispense the completed eyewear, slight adjustments to the position of the crutch may be required. The crutch should be covered with a soft material. It should be arched to follow the contours of the lid and be in such a position that the upper lid is supported by the crutch. This then holds the lid up above the pupil.
—Glenn M. Herringshaw, director, optical lab, Indiana University School of Optometry, Bloomington, Ind.
*Editor's note: Ptosis or blepharospasm is drooping of the upper eyelid. Blepharoptosis is an involuntary closing of the lid. These conditions may require a ptosis crutch to be installed on eyewear to keep the lid from closing. EB