In this inaugural "Fix and Fit" column, we will look at the methods involved in fitting eyewear to the patient. The steps taken here can make or break your business. Why? Because if the patient leaves your office with eyewear that is the latest style, but a poor fit, you may have lost his/her business forever.

During the initial assessment, ask the patient if he has anything special in mind. Then, form your own opinions. A clue is the individual's current eyewear. If the lenses are heavy now, ask if that has been a problem. Let him know from the start you are a problem solver.

If a frame doesn't fit, don't be afraid to say "no" to a patient when you are designing his/her eyewear.

Here are the specifics of what to look for, and how you can solve problems in the various aspects of fitting.

Bridge. Pay particular attention to the fit of the bridge and maximum weight distribution. A penlight will help to determine whether the angle is correct. If it is not, check to see if the angle can be altered in some way. For instance, you may want to induce a nasal fill to close up a space in the lower nasal area by putting some pantoscopic tilt on the endpieces. Either do it at this time, or make sure the frame has the potential for later adjustment.

Eye size. The outer edge of the frame should be even with the widest points on the head (usually just above the ears). The eye size is also contingent upon the prescription. It is not necessary to put a large frame on a large person.

Decentration amount. The difference between the frame P.D. -- eye size plus distance between lenses -- and the patient's P.D. is known as the decentration amount. The decentration amount becomes important rapidly on higher powered prescriptions. It is due to the decentration that a minus lens is thicker on the temporal edge, and a plus lens is thicker on the nasal edge. To minimize decentration, it is possible to dramatically reduce the overall thickness of the lenses by using a smaller bridge or eye size.

Eyewires. Long shapes, though sometimes stylish, can be poor lens holders. This is especially true with plus lenses because the higher base curves cause the eyewire to lift off the lens and pop it out. Using the new aspheric lenses is a good choice here. Eyewire barrels that protrude can also be a problem with heavier lenses, which require more tension and usually leave a gap in the eyewire.

Endpiece. Since most of the adjustments on a frame are done with this area, great care must be taken to ensure that any adjustment necessary for patient comfort can be made in the future. This would include pantoscopic and retroscopic tilt, temple spread or inward movement, and the ability to rotate for proper temple fold. If the lenses are very thick on the temporal edge, the endpiece will need to be long enough to allow the temples to close without touching the lenses.

Hinge. The hinge should be appropriate for the weight of the eyewear. A spring hinge may not be able to apply enough pressure to the mastoid area to prevent the eyewear from slipping.

Temples. Solid block end pieces are very limiting in their adjustment, but are also among the strongest. This goes to show that with a good initial fit, adjustment limitations are not always a bad thing. When selecting temples, make sure they can be curved inward slightly just after the widest point of the head. Remember, the secure feeling this creates for the patient will enhance the confidence he has in you.

Temples that are too short will cause problems. Make sure there is about 2mm of space between the temple and the back of the ear with skull temples. When fitting, be sure to follow the mastoid area closely. If the head allows, turn the temple tips inward to follow the taper of the neck. This will keep the temples from riding up the ear and down the nose. The temple length must allow approximately 40mm from bend to tip. Shorter is OK, but there must be really good contact in the mastoid area. If tension is insufficient, you can convert the temples to cable style. Kits are available for this purpose, and it is simple to do.

One final note on adjustments: Remember that when bending a frame, you must make well thought-out, purposeful adjustments. You, your employer, and our profession have a reputation at stake. So, do your best, and never stop learning. EB