[Declanomous]

I order my glasses from Zenni, but I don't think it's for everyone. For one thing, they always locate the pupil at the exact midpoint of the lens. Unless you wear very small frames, your pupils are probably located somewhat higher in the lens when you are wearing the glasses in the most comfortable or attractive manner. This can result in double vision, chromatic anomalies, headaches, and worse. It's far more likely to be an issue if you have a strong prescription than a weak one, but inexpensive glasses may be a false economy if you have any of these problems.

edit: Also, one pair of glasses I ordered from Zenni gave me a rash around my eyes and on my eyelids. I've gotten contact rashes from watches before, so it wasn't entirely unexpected, but I'd never had it happen with glasses before. I thought I had just gotten a sunburn at first, and it took me a while to convince myself it was my glasses. (I basically didn't wear the glasses for a month, and then wore them again.) It's either the plastic used for the frame, or maybe a mold release. Regardless, I've tried washing the glasses with a strong detergent, and I've had them ultrasonically cleaned and they still give me a rash. They cost $30 though, which basically makes them disposable compared to normal glasses.

[randomanon8187]

Sort of off topic, but the contact rash sounds familiar to me. It may be 'nickel allergy', it runs in my family. Any watches, bracelets, glasses, belts with nickel in them touching skin for a while seems to cause it.

[jobu]

> This can result in double vision, chromatic anomalies, headaches, and worse.

I can attest to this. My astigmatism is pretty severe, and the lenses are useless if any measurements are even slightly incorrect.

Usually when I get new lenses I end up sending them back at least once for one defect or another. Sometimes this is the frame tech's fault, but I've also seen quality issues from the lens factory.

[1123581321]

Anecdotal, but I have severe astigmatism and Zenni has worked well for me.

[rogerdpack]

Last time I ordered from (them or their competitor) they asked for PD (pupillary distance) is that enough or are the prescription ones still better?

[Declanomous]

Pupillary distance is basically the horizontal location of the pupils. The issue is that pupils can also have a vertical offset from the center of the lens as well. Accounting for PD alone is sufficient for some people. I'm not a doctor, so I'm not qualified to recommend one option over another. It is something you may want to ask your own doctor about though.

[dubyah]

To be fair to Zenni, most online eyeglass sites don't request vertical measurements as the PD is sufficient for the majority of single vision users and there isn't a single vertical measurement that can be applied from one user to other glasses. Ocular center height is very subjective & measured during the fitment of that frame to the user. Optical center being the same height as geometric center is a safe choice for something only made to measure.

There are sites that take segment height for bifocals, but the intended frames need to be in hand for the user to measure.

[rhizome]

Are there any magic words to account for this that I/we can use when getting a new prescription?