Prism Placement Direction

Esotropia - Base Out
Exotropia - Base In
Hypertropia - Base Down
Hypotropia - Base Up

Prism Removing Covering Method      

1. Operation Method: Cover the gazing eye with hand occluder place the prism in front of the deviated eye, cover the gazing eye repeatedly, and constantly adjust the degree of the prism. Until the gaze is covered, there is no eye movement in the deviated eye. Replace the eyes watching and repeat the above inspection.
2. Results Judgment: When the eye position is no longer moving, the degree of prism is the degree of patients with strabismus
3. Note: This method is applicable to the measurement of the degree of tropia, not only for common tropia, but also for uncommunicative tropia.

Prism Alternating Covering Method

1. Operation method: Hold the prism and put it in front of one eye according to the tropia direction. Cover the two eyes alternately, and constantly adjust the degree of the prism until there is no eye movement when covering alternately.
2. Results Judgment: When the eye position is no longer moving, the degree of prism is the degree of patients with tropia
3. Note: The prism alternating covering method is often used for common tropia. Otherwise, there will always be eye movement

Classification Of Tropia