THE OPERATION first described by Reese1 in 1912, whether carried out as originally designed or with minor modifications, is still the most widely employed technic for shortening an extraocular muscle.2 Yet the procedure, though based on sound surgical principles, does not always lead to entirely satisfactory results; this is mainly due to the difficulty of measuring with accuracy the amount of resection required. There exists, on the other hand, general agreement that extreme precision is of crucial importance in squint surgery.3 Accordingly, a number of devices have been suggested by various authors, intended to determine with greater exactitude the correct place for insertion of sutures and resection of the muscle.
Separate calipers or strabismus rules have been designed by Walker, Jameson, Green and others. But instruments which are not part of the advancement forceps are awkward to use and liable to produce inaccurate measurements. Berens4 attached
TOWER P. INCREASED ACCURACY IN SQUINT SURGERYReport of New Instrument. Arch Ophthalmol. 1950;44(3):395-398. doi:10.1001/archopht.1950.00910020404006