A new test has been devised to use in cases of refraction in which retinoscopy or astigmatic dial tests are unsatisfactory. An exact plan of cross cylinder testing is done to "scan" the principal meridians. The results are consolidated to indicate the approximate axis of astigmatism. The test is based on and conforms to computer methods.
Schwarting BH. Cross Cylinder Scan Test for AstigmatismA Computer Approach. Arch Ophthalmol. 1969;82(3):330-331. doi:10.1001/archopht.1969.00990020332006