Look out for spelling mistakes and punctuation errors on the package boxes. Almost any product with such errors is likely to be a cheap counterfeit.
The fonts in which any text either written on the box or on the manuals is written, can provide significant evidence to its authenticity. Fakes tend to have some blurry and, usually, poorly written text.
The color pigment on authentic contact lenses are on the exterior of the lens while with fakes, the pigment will be on the inside of the lenses.
Check for the labeling on the container of the lenses. It should be neat and not clumsy looking. Compare a fake with an original and you will see that they are not labeled uniformly because they have been done by hand.
Also its important to check the label design, as it might not even be the same as that of the original.
Each contact lens manufacturer may have a different way of capping their containers and may use certain unique symbols to indicate their authenticity. Most fakes don't have this feature as it is not easy to duplicate. It is important to compare both types and see the difference.
These are a few easy steps for to identifying fake contact lenses from original. It is also safer to buy your purchase from reputable stores. Don't forget to seek extensive medical advise before you ahead and purchase a pair of contact lenses.