| Jackson cross cylinder | |
|---|---|
 Jackson cross cylinder of power +/- 0.50 diopter | |
| Test of | Astigmatism |
| Based on | circle of confusion |
The Jackson cross cylinder (JCC) is an instrument used by ophthalmologists, orthoptists and optometrists in their routine eye examination, particularly in determination of corrective lens power in patients with astigmatism. It is also used for testing near point of the eye.