Rx Insert Wearers and Opticians : advice please

philkeeble

I wear a pair of Adidas EvilEye Half Rim Pros with an Rx insert. My prescription is R: -3.5, L: -5.25 with around an extra -2 of astigmatism in each eye. My daytime specs are fine at this prescription, but when I fitted an Rx insert of the same prescription my vision is less good and it feels as if the lenses are too strong for me. The insert sits VERY close to, but just not quite touching, my eyelashes. In comparison, my specs sit further away from my eyes. Holding the cycling glasses a little off my face (to increase the distance from my eyes) improves my vision.

Has anyone else ever noticed such a problem? I feel that the optical correction should be knocked back a little to compensate for the closer position of lens, but my optician is reluctant to supply me with an insert of the "wrong" prescription. I'd be keen to hear any advice that folk have based on their experiences similar to mine.

Or maybe I'm just special?!

(p.s. after a very recent cataract op, I'll probably be around -2.5 in the left eye now, so I'll need to get the insert replaced; hence the sudden urge to obtain other folks' views)

desweller

Get the lens checked.

The tolerances that lenses are allowed to use around a target prescription are quite large, apparently; I had Boots change a pair of new lenses after they made one lens at the top end of the tolerance and the other lens at the bottom; made for a very unbalanced experience!

I do use RX inserts in my specs (made by Specs by Post Ltd after a recommendation on this very forum) and they have been perfectly OK; no different to my normal specs. I am a -1.75 and -0.5.

I used to be a -8 and -9 prior to laser surgery about 10 years ago, with a fairly significant astigmatism to boot, but never had prescription sunnies in those days.

term1te

I'm surprised at your opticians advice. Surely the "correct" prescription is only correct when it sits a certain distance from your eye. Moving the lens closer will require a different "correct" prescription. My wife has a strong prescription and the position of her glasses makes a large difference to the quality of her vision. I'd be tempted to get a second opinion.

I went to the optician in the summer and he tried to sell me cycling glasses with built in corrective lenses. But as my bike costs only slightly more than the ones he was trying to flog me, I'll stick with inserts.

themogulman

If you Rx is over +/- 5 units then your prescription should include an extra specification called the BVD(back vertex distance) which is basically the distance from the apex of the cornea to the position of the lens when you were tested. This is typically 10-12mm.

With regard to tolerances of lenses they are pretty strict if they were checked correctly.

If you are supplied an optical device(spex/sports spex/ rx insert etc) that does not sit in the same position then your optician should alter the power of the lens.

TBH with your RX its probably not the BVD that is the issue(unless your BVD was say 15 mm and your insert sits at 9mm for instance) its more to do with how IMO crap RX inserts are. If you new rx is likley to be -2.5 ish then relax.