You can wear contacts in the tanning bed but it's recommended to remove the contacts before tanning.
When you're in a tanning bed the tanning UV rays can dry out the contact lenses and cause them to stick to your eyes.
Wearing the tanning goggles helps when you're wearing contact lenses in the tanning bed but it's best to remove the contact lenses first and then wear the tanning goggles and then put the contact lenses back into your eyes after you get done tanning.
Also tanning dehydrates your skin which is also why it dehydrates your eyes as well.
Using a tanning bed even once could possibly give you cancer.
However it would be a rare chance that you would get cancer just from using a tanning bed only once.
Usually it takes several tanning sessions in a tanning bed over a few years or longer to develop cancer from the tanning bed.
Many people use tanning beds for years and never develop cancer such as skin cancer but some people develop cancer after a few tanning sessions in a tanning bed.
Tanning in a tanning bed is never really a healthy thing to do because the UV rays from the tanning bed are more dangerous to your skin than tanning in the natural sun.
Tanning in the natural sun gives you Vitamins which can be healthy and it's less harmful to tan naturally using the sunlight than to tan in a tanning bed.