To help you decide whether flip up sunglasses or spring-fit clip on sunglasses are a better choice for your requirements, here are the relative benefits of each type.
Spring-fit clip on sunglasses are more refined in appearance.
The fitting mechanism is neat and unobtrusive and when fitted to spectacles the overall appearance is not dissimilar to wearing prescription sunglasses. In comparison, flip-up sunglasses have a noticeable central bracket and hinge mechanism at the top of the frames.
For comfort, the spring-fit type of clip on sunglasses is generally regarded as preferable to the flip-up type. Some people find the clip attachments on the flip-up type can intrude slightly on their vision. Also the width between lenses on flip-ups tends to be narrower than on the spring-clip type so if your glasses have a wide nose bridge, you may notice the inner edge of the clip on lenses intrudes on the nose rests of your prescription frames.
Ease of fit
The best results with spring-fit clip on sunglasses are obtained if you can select a lens shape and size that corresponds closely to the appearance and dimensions of your prescription frames.
On the high street, the choice of sizes and shapes of clip-ons tends to be extremely limited even in high season. Fortunately, Eyewear Accessories has a choice of 70 different spring-fit models to suit most requirements. However, spring-fit clip on sunglasses will not fit every prescription frame.
If you have plastic spectacle frames with chunky rims that are over 4-5 mm thick, the flip up type of attachment is more suitable. This also applies if you have thick lenses over 5 mm thick.
If you are having difficulty finding a model of spring-fit sunglasses to fit your frames, the solution is to go for the flip-up type, where exact fitting is less critical.
When selecting flip-up sunglasses, you start by choosing the most appropriate shape for your prescription lenses and then check the measurements of the flip-ups against your frame.
We recommend that you select a size of clip-ons with lenses at least 4 mm wider and deeper than your frames. Also check the width of your glasses to ensure that you select a model of flip-ups that will span them comfortably.
Flexibility in use
The flip-up type of sunglasses has advantages in terms of flexibility for some applications.
Some people find them preferable for driving because you can flip up the tinted lenses easily if the sun goes in or you drive into a shaded area, and then can flip them down again when you need the filters to block the glare. The same flexibility appeals to some fishermen when fishing in variable light conditions.
Cost and durability
Flip up sunglasses tend to be less expensive to buy than spring-fit clip on sunglasses. However, they tend also to be less durable so you may need to replace them sooner.