Squinting
 

I had to do an eye test. Part of the test was called "squinting". What is this for? What influnce does it have on my vision? What exactly is squinting?

A squint is one form of cross eye or strabismus.

In medical terms, a squint is when the two eyes are not focused on the object under scrutiny. An uncorrected / untreated squint in childhood leads to failure of development of the squinting eye, with poor vision in that eye, a condition known as amblyopia. There are various ways to test for squints, which can be latent (i.e. hidden) or manifest. This is presumably what they did to you.

A 'squint' in non-medical parlance, of course, is when you screw up your eyes to protect them from bright light.

QDM