Draw a closed loop along the dashed lines. The arrows in the grid indicate the direction(s) in which the loop is closest when looking from that cell.
(Rules and example from WPC 2017 IB)
History of the puzzle
First appeared on Kwon-Tom Loop (online Slitherlink game website) forum in 2009. Author of the puzzle was user Jankonyex (Taiwan). The name Myopia was given when this puzzle appeared on the Puzzle Picnic website in 2011. Puzzle Picnic version of Myopia introduced additional white arrows.
In theory, Myopia arrows work with any puzzle where some cells are filled with symbols while the others remain blank (which is almost every puzzle). The most well known Myopia-related puzzle is probably Pentopia.
WPC 2016/Round 10 was a round that solely consisted of Myopia-related variants.