Your tears have an oil seal on top — and yours is thinning
Your tear film isn’t just water. There’s a thin layer of oil sitting on top of it, and that oil is the seal that stops your tears evaporating off the surface of your eye between blinks.
When that seal is strong, your tears stay put and your eyes feel comfortable. When it goes thin, your tears evaporate in seconds — no matter how many you have. That’s why your eyes can stream all day and still feel bone dry. The watering is your eye panicking and flooding itself with tears that have no oil to hold them in place.
The oil layer is the seal. Drops are just water.