It is remarkably consistent. Fine in the morning, fine after lunch, and then somewhere between two and four o'clock the eyes turn to sandpaper and stay that way until bed. Here is why the bottle on the desk stops helping.
You are blinking about a third as often as you should
Concentration suppresses the blink reflex. At a screen, most people drop from around fifteen blinks a minute to five, and a large share of those are incomplete, which is worse than it sounds.
Drops treat the surface, and the surface is not where it starts
Artificial tears add volume. They do nothing about why the film is breaking up in the first place, which is why relief lasts twenty minutes and then the clock resets.
No obligation. It opens the official page.
The oil layer is usually the actual problem
Tears are not just water. A thin oil layer on top stops them evaporating. When the glands producing that oil are sluggish, no amount of watery drops will hold the film together.
Preservatives in the cheap bottles make it worse over months
This is why people report a bottle that worked in March doing nothing by July, and why preservative-free vials exist at four times the price.
Warm compresses help some people and irritate others
The advice is given universally. The results are not universal, and a meaningful number of people report their eyes are angrier afterwards.
Prescription drops take months and often do nothing
Restasis, Xiidra and the rest are a long commitment with a burning sensation at the start. Some people get real relief. Plenty describe months of burning followed by nothing.
