What lenses are best for semi rimless and rimless glasses?

What lens thickness should I choose?

If you’re moderately, or very short sighted you’ll benefit from thinner lenses as the edge thickness of your lenses will be more visible and cut to a flat finish to allow for a groove to be cut and through which your nylon to hold your lenses in place can be seated.

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Lenses with a refractive index of 1.6 are ideal for prescriptions where the value of your SPH prescription is between -2.50 and -4.00 (ideal for no rim glasses) and have the least peripheral distortion of high index thinned lenses. These lenses offer little distortion and are stronger than other lens types so are recommended for full and semi rim glasses styles.

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So, what lenses are best for semi rimless and rimless glasses? lenses between -4.00 and -6.00 we’d recommend a lens with a refractive index of 1.67, and any prescriptions over that a lens with a refractive index of 1.74 will be more suitable.

If your prescription is over -5.00 we’ll need an accurate measurement of the distance between your pupils, often referred to as the PD.

So, What lenses are best for semi rimless and rimless glasses?

Firstly, lenses for long- and short-sightedness are different, there are different considerations for each.

Semi Rimless glasses frame. What lenses to use?

About Refractive lens index' - The refractive index of a standard index plastic spectacle lens is 1.5.

Mid Index - A mid-index lens with a refractive index of 1.6 is about 20% thinner than a standard lens.

Higher Index - A high-index lens with a refractive index of 1.67 is approximately 33% thinner, while a lens with a refractive index of 1.74 is around 42% thinner. These lenses are suitable for semi rim glasses but are not as strong as the 1.6 index lens.

Reflect More Light - Lenses with a refractive index of 1.67 and higher reflect about 50% more light than standard index lenses. Therefore, it's common to apply a multi-anti-reflection coating to reduce reflection (although this is a matter for the wearers preference). These coatings lessen glare particularly from headlights at night.

Considerations - What lenses are best for semi rimless and rimless glasses?

A frame with a lens diameter exceeding 52mm can increase lens thickness although sometimes needed through customer choice or necessity for extra wide glasses. This might be because of a need for a wider fit. In these circumstances, frames that are wider can be considered.

1. If you prefer semi-rimless or rimless frames, be aware that lens edge and centre thicknesses can look and be greater because a flat edge finished lens is required (lenses are more noticeable than a lens fitted to a full rim or even plastic rim frame).

2. + Plus Prescriptions - With a plus (+) prescription, the edge thickness of your lenses (the thinnest part) will need to be increased for successful glazing into the frame, increasing the centre thickness of the lenses and making the lenses appear more pebbly in the centre and thicker on the edges.

3. - Minus Prescriptions - With a minus (-) prescription, the outer edges of the lenses are the thickest part. Semi rim and rimless frame styles have to have thicker lenses (than full rim frames) to accommodate the small cut-in groove for the nylon wire to hold the lenses in place or for drilling holes into a full rimless frame. The minimum thickness on the edges of lenses glazed into these types of frame is 2.5mm, and depending on prescription (the higher) this can increase. The minimum thickness may be thicker than the same lenses fitted to full rim frames.

4. Coatings - An anti-reflection coating is an additional extra with varifocal lenses although it generally comes as standard on single vision lenses if they are stock (mass produced) and can reduce bothersome reflections from the lens surfaces.

5. The Cons - This coating adds extra cost and is sometimes is not preferred by wearers because the down side to this sort of coating is that it easily greases when wearing due to the atmosphere or handling, so need more frequent and careful cleaning.

6. Choice - Ultimately the choice of lens, thinning options, anti glare coatings and frame styles and sizes remains a matter of choice and preference. You can contact us or call in to our dispensing eyewear boutique when our store is open for more advice.