Diamond-phenomenon

Y-phenomenon: The number of out-slopes is small or absent at the original eye position and when looking straight down, while the number of out-slopes increases significantly when looking straight up. It is actually a variation of V-exotropia. ◇ -phenomenon: That is, when the original eye position, the number of inclination is small or no inclination, and the number of inclination increases when looking up and down, both of which are AV synthesis Performance.