To the Editor.
—Bielschowsky1 was the first to recognize the value of using a head-tilt test in the diagnosis of oblique muscle palsy. It remained for Parks2 to clarify the considerable confusion that developed by explaining the role of the superior and inferior recti, as well as that of the oblique muscles, in the mechanism of hypertropia. Parks2 referred to these eight muscles as "cyclovertical muscles" and described a three-step test that can be used to identify the paretic muscle.Further discussions on cyclovertical strabismus can be found in two articles by Hardesty.3,4 It is not the intention of this letter to detail material already adequately covered. Instead, a simplified approach to diagnosis of the paretic cyclovertical muscle is proposed.When a hypertropia due to a paretic muscle exists, any of the eight cyclovertical muscles may be at fault. These are the superior and inferior recti
Todd GP. Simplified Diagnosis in Vertical Strabismus. Arch Ophthalmol. 1973;90(6):510-511. doi:10.1001/archopht.1973.01000050510022