If the Frame Fits…Wear it!

A comfortable well-adjusted frame can mean the difference between your client knowing that they have the best pair of spectacles they have ever had, or the worst.

In this article I'm going to discuss the importance of selecting the right frame for your client and the steps you can take when selecting that frame. Although a correct fitting frame is a rule for every pair of spectacles dispensed, I will be focusing mainly on selecting the right frame for progressive lenses as, in my opinion; this is possibly the most critical.

Progressive lens technology has significantly advanced over the past few years. We have seen the original 'hard design' lenses, with much more severe peripheral distortion and less adaptation success, replaced with lenses from every manufacturer out there offering a 'wider field of view' and softer distortion areas meaning greater adaptation success.

More recently, we've seen the introduction of lenses that are not only designed according to a patient's prescription, but also to their lifestyle and how they move their head and rotate their eyes. No longer are your clients limited to selecting a frame with a minimum depth of 24mm, as there is a progressive lens suited to every size frame out there! Ask yourself this question: Is it worthwhile giving your client such a state-of-the-art lens and then expecting them to live happily-ever-after if the frame isn't fitting correctly in the first place?

Although not being a progressive spectacle wearer personally, the one thing that I have always thought is that wearing progressives would be like looking through a keyhole. To explain this a little more clearly; the closer your eye is to the keyhole, the more you see on the other side.

The same can be said for progressive lenses due to the distinct regions of 'optimum vision', also known as the 'corridor'. The closer the lenses are to your eyes, the wider the field of vision that will be achieved. And as dispensers, we all know that progressive lenses + wide field of view at all distances = happy client!

So what is the right frame and what should you look for when helping your next client?

I have always considered two important points when doing so.

1. Selecting the right size frame

2. Adjusting the frame

The latter will always be made easier providing the right size frame has been chosen.

Have you ever tried to adjust a frame that in your opinion sat too high due to a narrow bridge, or left grooves on the side of the person's head as the frame was not wide enough? Adapting the two principles into your selection prior to taking any lens measurements will not only improve the comfort of the frame for the wearer, but also minimise potential problems down the track.

Selecting the Right Size Frame

There are four main points to consider when selecting the right frame size for your customer.

Eye Size
Ideally, select a frame where the pupils are reasonably central in the eye size of the frame. This is an important factor especially with higher prescriptions as it will help to minimise unwanted lens thickness (least amount of decentration
= less lens edge/centre thickness).

Bridge Size
Select a frame with a suitable bridge width. Use a large bridge size for wide noses or a narrow bridge size for narrower noses to ensure a comfortable fit. A frame with adjustable pad arms is ideally best for fine-tuning. A frame with a poor fitting bridge will affect the vertex distance and again affect the performance of the lenses therefore limiting the chances of achieving the desired distance.

Temple Length
Make sure that the temples are long enough so that they can be adjusted correctly around the ear (anatomical bend). Temples that are too short will cause excessive pantoscopic tilt and thus alter the way a customer sees through their spectacles.
Be sure to adjust the temples on your
client prior to lens measuring.

Frame Width
Ensure that the frame is wide enough and that the temples do not push into the side of you client's head, leaving unsightly grooves. Not only is this uncomfortable for your client, it will also cause the frame to push forward and slip down the nose.

Adjusting the Frame
Once the frame has been chosen, it is then important to make adjustments. Consider the following factors to ensure optimum visual performance from the lenses.

Pantoscopic Tilt
This is the angle at which the vertical plane of the frame rests against the horizontal visual axis of the eye with the lenses tilted forward (toward the cheek). An ideal fitting frame will normally have between 7-12 degrees of pantoscopic tilt (while making sure the frame doesn't touch the cheek). This will provide your client with the maximum amount
of reading area in their lens.

Vertex Distance
Vertex distance is the distance measured between the back surface of a corrective lens and the front of the cornea. For progressive lens fitting it is important to keep this measurement to a minimum (under 14mm), as this will benefit your client with the 'keyhole effect' by creating a wider field of view.

It should be noted that for higher prescriptions the vertex distance measurement should be checked against the refractor head vertex distance in case the prescription needs to be altered by
the prescriber.

Dihedral Angle (Facial Wrap)
This is an adjustment to the frame front to suit the wearer's face shape. A correctly fitted frame will have an angle of between 3-5 degrees.

The tools required to measure and adjust these elements are generally available from your lens and/ or spare parts manufacturer.

As mentioned earlier, once selected the spectacle frame should be fitted on your client as if it was a 'final fit' prior to taking any lens measurements. As a general rule spectacle frames should be adjusted from front to back, therefore making it necessary to recheck the temple bend (anatomical bend) after all other adjustments have been made.

Brendan Gorzalka is a qualified optical dispenser practising on the NSW South Coast. He achieved a national award after graduating with straight distinctions in 2002, and has since completed
the Diploma in Ophthalmic Management, again with distinction.