BACKGROUND/AIMS: Graded vertical rectus tenotomy (GVRT) is postulated as effective for small-angle vertical heterotropia. We aimed to determine the dosing recommendations for GVRT in sagging eye syndrome (SES). METHODS: This was a retrospective, observational study of surgical outcomes for GVRT from 2009 to 2014 in a single surgeons academic practice. There were 37 (20 women) patients of average age 68±10 (SD) years with comitant or incomitant hypertropia ≤10Δ caused by SES. The main outcome measure was the dose-effect of GVRT required to correct intraoperative hypertropia. RESULTS: Preoperative average central gaze hypertropia measured 4.7±2.2Δ. Three patients underwent repeat GVRT for residual or consecutive hypertropia, one undergoing it twice. All surgeries were analysed, increasing the total operations to 41. The inferior rectus tendon in the hypotropic eye was operated in 32 eyes, and the superior rectus tendon in the hypertropic eye in 9 eyes. Mean tenotomy was 68±19% of tendon width. Hypertropia was always eliminated intraoperatively by progressive GVRT. Mean hypertropia was 1.1±1.6Δ at average 93 days postoperatively. Linear regression demonstrated that 3-6Δ hypertropia correction requires 30%-90% graded tenotomy (R(2)=0.32, p<0.0001), but with substantial individual variability. Undercorrection necessitated reoperation in 10% of cases. CONCLUSION: GVRT precisely corrects hypertropia of up to 10Δ, but because of variable effect, it should be performed with intraoperative monitoring under topical anaesthesia.

PURPOSE: Medial transposition of the split or intact lateral rectus (LR) muscle in oculomotor palsy improves extreme exotropia. We studied rectus pulley positions using high-resolution surface coil MRI before and after LR split with medial transposition surgery in a patient with bilateral oculomotor and trochlear nerve palsies. METHODS: This is a report of a 14-year-old girl with 90Δ exotropia due to bilateral oculomotor and trochlear nerve palsies following traumatic midbrain infarction at age 6 years. Surgery comprised longitudinal division of each LR into a superior and inferior, threading of both halves between the inferior rectus (IR) and inferior oblique inferiorly, and inferior to the superior oblique and the superior rectus superiorly, with suturing of each 10 mm posterior to the medial rectus (MR) insertion. RESULTS: Pre-operative MRI of the orbit and extraocular muscles (EOMs) with thin, 2-mm slices revealed bilateral atrophy of all EOMs supplied by the oculomotor and trochlear nerves. Post-operative MRI at 2 months demonstrated no significant changes in rectus EOM pulley positions compared with pre-operative values. CONCLUSIONS: The LR pulley does not change position even after split LR transposition to the MR insertion, confirming the profound constraint of the connective tissue pulley system on the LR path.