(from David G. Hunter MD, PhD)
| Horizontal Deviations | ||||
|---|---|---|---|---|
| Deviation | ET | XT | ||
| PD | Rec | Rst | Rec | Rst |
| 15 | 3 | 3 | 4 | 2.5 |
| 20 | 3.5 | 4 | 5 | 3 |
| 25 | 4 | 5 | 6 | 4 |
| 30 | 4.5 | 6 | 7 | 5 |
| 35 | 5 | 7 | 7.5 | 5.5 |
| 40 | 5.5 | 7.5 | 8 | 6 |
| 50 | 6 | 8 | 9* | 7 |
| 60 | 6.5 | 8.5 | 10* | 8 |
| Vertical Deviations | ||||
| Recess up to 1 mm for each 3Δ of desired correction | ||||
Explanation:
This is shorthand notation that can be used for bilateral medial rectus surgery, bilateral lateral rectus surgery or for a unilateral recess/resect procedure. It can also be used for single muscle surgery.
To use the table, select the row corresponding to the deviation. Each muscle operated the specified amount will then correct half the deviation.
* Do not perform bilateral lateral recessions for XT of 50 or more; for that size angle, at least one muscle should be resected
Examples:
To correct an ET of 40Δ, perform bilateral medial rectus recessions of 5.5 mm, or bilateral lateral resections of 7.5 mm, or a recess/resect procedure of 5.5 and 7.5 mm.
To correct an ET of 10Δ, perform a unilateral medial rectus recession of 3.5 mm.
To correct an ET of 60Δ using 3 muscles, perform bilateral medial rectus recessions of 5.5 mm to correct 40Δ, and add a unilateral rectus resection for the last 20Δ.