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Message: <blockquote data-quote="looksharp65" data-source="post: 3379542" data-attributes="member: 83771">Matthew,I'm an optician/optometrist and I'm astonished with what you tell us here.The spectacles with the faulty IPD's should never have left the shop. If your prescription is -10 D and the mounting error is 0.2 cm, the resulting prism effect will be 2 prism diopters. That is way out of tolerances.For horizontal prism effects, the tolerance is 0.50 prism diopters and for vertical, no more than 0.25 prism diopters is acceptable.To put it frankly, they screwed you and sold you substandard products.Furthermore, their explanation is intolerable. While it is true that edging high-power, high-index lenses is most demanding and errors occur, that's no excuse for leaving you with an unusable pair of spectacles.If they don't know how to avoid the errors, for example by edging test lenses of similar power to find out if tweaks have to be made, they should swallow the pride and send the frame to the lens manufacturer so they can deliver a faultless product.It is indeed more difficult to handle lenses of strong powers. Not only because of the above-mentioned edging and centration issues, but also because the frame may not always rest in the intended position, and small adjustments of the frame can induce significant prism effects and discomfort.I and my colleagues agree that if the highly ametropic spectacle wearers weren't so uncomplaing, making spectacles for them would be a nightmarish and next to impossible task.There are occasions, and they are not very rare, when the correction of each eye individually will be useless because of the two lenses's individual distortion pattern, magnification/minification and prism effects occuring with oblique gaze directions. Another special case is convergence anomalies, where progressive lenses of standard parameters will fail, but highly tailored versions may be usable.I regret your previous experiences with spectacle purchases, but do hope you will realise that buying them online won't ensure success.On the contrary, my view is that buying spectacles online means a step down in quality and more or less a lottery.Your eyes deserve the best, so try to find a vendor with a solid reputation of being able to handle challenging prescriptions and (not least) with a solid complaint handling policy.//L</blockquote>

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