You Do Need power plug adapter while traveling from Slovakia to Laos.

Here is Why You Need An Adapter

The outlet and plug type used in Laos are A, B, C, E and F and in Slovakia are C and E. This is how they look like.

Slovakia

In Slovakia, outlets of type C and E are in use.

Type C

Type E

Laos

In Laos, outlets of type A, B, C, E and F are in use.

Type A

Type B

Type C

Type E

Type F