7 The Parks–Bielschowsky three-step test (3ST) has long been the workhorse for diagnosing cyclovertical strabismus. It has been widely assumed that the response of HT in SOP to head tilting provides diagnostic specificity. Machine learning substantially but imperfectly improves classification accuracy. Supervised machine learning of alignment data distinguished the diagnoses with areas under the receiver operating curves up to 0.93, representing excellent yet imperfect differential diagnosis.īecause the 3ST is often positive in SES, clinical alignment patterns may confound SES with unilateral SOP, particularly acquired SOP. In SES, nine subjects (50%) fulfilled the 3ST and had greater infraplacement of the lateral than medial rectus pulleys in the hypotropic orbit. In both SOP and SES, hypertropia increased in contralateral and decreased in ipsilateral gaze and was greater in ipsilateral than contralateral head tilt. Inferior oblique cross-sections were similar in SOP and SES. Maximum cross-section of the palsied SO was much smaller than contralaterally and in SES ( P < 2 × 10 −5). Eighteen others had normal SO size but MRI findings of SES. Twenty-three subjects had unilateral SOP manifested by SO atrophy. Rectus pulley coordinates were determined in SES cases fulfilling the 3ST. Multiple supervised machine learning methods were employed to evaluate diagnostic accuracy. Alignment was measured by Hess screen and prism-cover testing. We studied hypertropic subjects who underwent surface-coil magnetic resonance imaging (MRI) demonstrating either SO cross-section reduction indicative of congenital or acquired palsy (SOP group) or lateral rectus muscle sag (SES group).

We sought to determine if alignment measurements can distinguish unilateral SOP from hypertropia in SES. Although the three-step test (3ST) is typically used to diagnose superior oblique palsy (SOP), sagging eye syndrome (SES) has clinical similarities.

Binocular prism alignment