SPEED OF ONSET

Rapid onset

If the onset is very rapid, indication is an auto-immune inflammatory response or bacterial. In my case there was rapid onset, so I suspect auto-immune or bacterial cause.

Slow onset

If onset is slow, then could be related to poor diet/ deficiency/ dropout of mebomian glands/ slowing down of lachrymal glands/ something that is affecting goblet cells (mucin).

EYE PARTS AFFECTED

MUCOUS LAYER goblet cells [almost certainly affected]

WATER LAYER lachrymal glands

OIL LAYER mebomian glands

Can pain be reduced by directly closing off signals from the relevant nerve?

One way to reduce pain would be to take a pain killer for the cranial nerve V (trigeminal). The ophthalmic nerve (V₁) carries sensory information from the cornea.