Two golfers can read the same putt correctly and see two different lines, because their eyes are in different places. Eye line is one of the few things in golf that is genuinely simple to measure and almost never measured.
Why it distorts what you see
You aim along a line you perceive. If your eyes are inside the ball, your brain constructs a line that runs slightly right of the true one. You then make an accurate stroke down a line that was wrong before you started.
This is why some golfers seem to miss on the same side forever despite a decent stroke.
How to check it in ten seconds
Set up to a ball as normal. Hold a second ball between your eyes and drop it. Where it lands tells you where your eyes are.
- Lands on the ball or fractionally inside: good.
- Lands well inside: you are likely pushing putts.
- Lands outside: you are likely pulling them.
How to adjust
Change your distance from the ball, not your posture. Standing slightly closer moves the eyes out over the line. Standing further away moves them inside. Make the change small, then re-test.
Why a mirror is the standard tool
The ball drop test is a snapshot. A mirror gives you the same information on every single putt, which matters because eye line drifts as you get tired or tense. Seeing your own eyes in the reflection is instant, unambiguous feedback that no amount of feel can replace.
One caution
Directly over the ball is not automatically correct for everyone, and some very good putters sit slightly inside. What matters is that your eye line is consistent and that you know which way it biases you. Consistency beats theoretical perfection.
