There are several different cosmetic options available to people who are interested in thicker or longer eyelashes. If you are tired of using eye makeups, which is obviously the cheapest, simplest, and safest solution, then you will need to talk to a specialized cosmetologist or your trusted plastic or cosmetic surgeon
The next level of intervention for longer or thicker lashes would be eyelash extensions. These can be applied by specially trained cosmetologists, often working in a doctor's office. Individual extensions are glued onto the upper eyelids, leading to longer and thicker lashes. This is a semipermanent solution which can last several months with some luck. They are quite expensive.
There is also a delicate plastic surgery intervention which involves transplanting hairs from the scalp to the edge of the eyelids to fill in the lashes. This is a permanent solution which will result in thicker or longer lashes. However, it is extremely expensive and will not be covered by your insurance, if that is a concern.
Finally, there is one relatively new medication, Latisse (bimatoprost), which has been approved to increase eyelash thickness. If this is an option that interests you, you should talk to your dermatologist
to see if it is a possibility.