They slit your eyeball open and flip up the top.

医生把眼球割开 然后把它往上翻。

The way I use this is that I just flip the top down, and then I place all the bigger, bulkier items in the middle.

我使用这个的方式是，我会把上沿下折，然后把较大、较笨重的物品放中间。