I am no expert on Viscotears...I don't even know if that's an OTC eyedrop or an Rx. What I can tell you is that eyedrops are, indeed, absorbed by the body. They may be absorbed in minuscule amounts, but they do enter the body.
I am currently pregnant with my second child post-LASIK (and dry-eyed). I have two others from my "previous life" before LASIK. I've always considered OTC eyedrops to be safe. In fact, I'm certain I asked that question of my obstetrician. I use Dr. Holly's eyedrops (Dwelle and Nutratear) exclusively, and never give it a second thought.
I did experience an eye infection with my last pregnancy and needed an Rx eye ointment...erythromycin. It was determined to be safe during pregnancy, so I did use it with confidence. I have avoided Restasis, however, though I have had urges in the last several years to try it.
I will add that I do well understand your concerns with product use during or pre-pregnancy. It's well worth taking the time to consider the safety of the baby. You might feel better if you pose the question to your doctor eventually.
Best of luck to you.
Never play leapfrog with a unicorn.