Excerpt from the book, requires clarification.

All the long morning, we stood in the open, enveloped in dust, sweating in the sun, which beat down on the sandy stretch, as devoid of shelter as Salisbury Plain. All afternoon, still standing, we watched the battle between two mechanized forces until my eyes watered with the glare and my feet seemed to big for my shoes.

What does narrator mean when he says that his eyes watered with the glare?

1. The glare of the sun caused his eyes to water

2. His eyes watered so much from the sun that light diffraction made him seeing the glare around objects

3. His eyes were drenched in glare, inundated by it.

4. Something else.

Thank you in advance.