Surgery for Supranuclear Monocular Elevation Deficiency

A Novel Technique Using Paretic Superior Rectus as a Globe Suspender for Monocular Elevation Deficiency

Surgical innovations in strabismus provide opportunities to improve visual function, eye alignment, and cosmesis in rare pediatric ophthalmological conditions. Monocular elevation deficiency is a rare and multifactorial disease in which the affected eye is equally limited in terms of elevation during adduction and abduction. We aimed to present a novel procedure for the treatment of acquired monocular elevation deficiency using the paretic superior rectus muscle as a globe suspender to resolve hypotropia. We report the case of an eight-year-old girl with left eyelid ptosis and hypotropia two months after draining a left orbital abscess. Left inferior rectus muscle recession was performed at five years, with residual left hypotropia. Ophthalmological examination revealed a best-corrected visual acuity of 20/20 OD and 20/100 OS. Severe left eyelid ptosis and poor levator function were also observed. Extraocular motility showed left hypotropia of 40 prism diopters with the left superior rectus muscle under action (-4) in the adduction and abduction positions. A force duction test negative for restrictions on the inferior rectus muscle was performed intraoperatively. To reduce the risks of the Knapp procedure, the left superior rectus muscle was split into medial and temporal halves. Double-armed sutures were secured in half, and the halves were detached from the sclera. The medial and temporal halves were reattached anteriorly to the medial and lateral rectus insertions, respectively. Eight weeks after surgery, the patient had nine prism diopters of hypotropia in the primary gaze. Ten weeks after surgery, there was no change in visual acuity. In the cover test, the patient exhibited residual left hypotropia of nine prism diopters with a restriction (-4) of elevation in adduction and abduction. The parents were pleased with the satisfactory cosmetic outcomes, and postoperative clinical photographs of the patient showed improved hypotropia and persistent minimal elevation of the left eye during adduction and abduction. Superior rectus muscle splitting and vertical transposition to the medial and lateral rectus could be safer and simpler alternatives to the Knapp procedure and may offer a lower risk of anterior segment ischemia. Further studies are required to confirm these findings.

A Digital Telehealth System to Compute the Myasthenia Gravis Core Examination Metrics

Background

Telemedicine practice for neurological diseases has grown significantly during the COVID-19 pandemic.Telemedicine offers an opportunity to assess digitalization of examinations and enhances access to modern computer vision and artificial intelligence processing to annotate and quantify examinations in a consistent and reproducible manner. The Myasthenia Gravis Core Examination (MG-CE) has been recommended for the telemedicine evaluation of patients with myasthenia gravis.

Objective

We aimed to assess the ability to take accurate and robust measurements during the examination, which would allow improvement in workflow efficiency by making the data acquisition and analytics fully automatic and thereby limit the potential for observation bias.

Methods

We used Zoom (Zoom Video Communications) videos of patients with myasthenia gravis undergoing the MG-CE. The core examination tests required 2 broad categories of processing. First, computer vision algorithms were used to analyze videos with a focus on eye or body motions. Second, for the assessment of examinations involving vocalization, a different category of signal processing methods was required. In this way, we provide an algorithm toolbox to assist clinicians with the MG-CE. We used a data set of 6 patients recorded during 2 sessions.

Results

Digitalization and control of quality of the core examination are advantageous and let the medical examiner concentrate on the patient instead of managing the logistics of the test. This approach showed the possibility of standardized data acquisition during telehealth sessions and provided real-time feedback on the quality of the metrics the medical doctor is assessing. Overall, our new telehealth platform showed submillimeter accuracy for ptosis and eye motion. In addition, the method showed good results in monitoring muscle weakness, demonstrating that continuous analysis is likely superior to pre-exercise and post-exercise subjective assessment.

Conclusions

We demonstrated the ability to objectively quantitate the MG-CE. Our results indicate that the MG-CE should be revisited to consider some of the new metrics that our algorithm identified. We provide a proof of concept involving the MG-CE, but the method and tools developed can be applied to many neurological disorders and have great potential to improve clinical care.

Comparison of different tendon transposition techniques for the treatment of monocular elevation deficiency type 2

PURPOSE

To compare results of three different tendon transposition techniques (Knapp procedure and two modified techniques) for the treatment of type 2 monocular elevation deficiency (MED) patients.

METHODS

The medical records of patients with MED type 2 operated on at a single institution from 2000 to 2016 were reviewed retrospectively. Patients were divided into three vertical transposition groups: (1) full tendon width, (2) augmented surgery; and (3) partial tendon width. Surgical success was defined as no severe limitation of upgaze, hypotropia of <6^Δ, and no hypertropia in primary position. Pre- and postoperative vertical deviations in the primary position and limitations in elevation levels were compared.

RESULTS

A total of 39 patients were included. The pre- and postoperative deviations in the full-tendon group were 22.50^Δ ± 4.17^Δ and 3.50^Δ ± 1.27^Δ, respectively; in the augmented surgery group, 23.75^Δ ± 4.78^Δ and 1.75^Δ ± 1.14^Δ; and in the partial-tendon group, 20.50^Δ ± 3.98^Δ and 4.12^Δ ± 2.78^Δ. Corrected vertical deviations were 19^Δ, 23^Δ, and 16^Δ, respectively. The pre- and postoperative limitation of elevations were -2.80 and -0.80 in the full-tendon group, -3.20 and -0.90 in the augmented surgery group, and -2.37 and -1.12 in the partial-tendon group. The pre- and postoperative vertical deviation improvements and limitations of elevation were statistically significant (P < 0.05) in all groups. Success was achieved in 29 patients (74%).

CONCLUSIONS

In this study cohort, all three procedures were reasonably effective in improving vertical deviations and limitation of elevation.

Surgical Management in Type 1 Monocular Elevation Deficiency

PURPOSE

To evaluate the outcome of surgical treatment in patients with type 1 monocular elevation deficiency.

METHODS

Patients who were diagnosed as having type 1 monocular elevation deficiency by forced duction test and exaggerated traction test between 2000 and 2016 were retrospectively reviewed. Epidemiologic and clinical features of the patients were noted. The efficacy of ipsilateral inferior rectus recession to vertical misalignments and limitation of elevation were evaluated. The clinical features of the patients who did not achieve surgical success after inferior rectus recession were determined. The surgical and functional results of contralateral superior rectus recession were evaluated for patients who had residual hypotropia under inferior rectus recession.

RESULTS

Thirty-nine patients were included in the study. Preoperatively, vertical deviations were 20.53 ± 4.50 prism diopters (PD) for near and 22.21 ± 5.12 PD for distance. After inferior rectus recession, the amount of vertical deviation corrected was 15 ± 1.14 PD for near and 17.01 ± 2.00 PD for distance. Ten (25.64%) patients did not achieve surgical success (> 6 PD residual hypotropia). Nine patients (preoperative inferior rectus recession measurements = 28.77 ± 7.25 PD for near and 27 ± 7.44 PD for distance) underwent contralateral superior rectus recession as a second surgery. After contralateral superior rectus recession, 7 of 9 (77.78%) patients achieved surgical success. The limitation of elevation significantly improved after both surgeries (Wilcoxon test, P < .05). No diplopia or other complications after surgeries were reported.

CONCLUSIONS

Inferior rectus recession is the first surgical option for patients with type 1 monocular elevation deficiency. Contralateral superior rectus recession is an effective alternative surgical treatment for residual hypotropia after ipsilateral inferior rectus recession. [J Pediatr Ophthalmol Strabismus. 2018;55(6):369-374.].

To assess the efficacy of vertical muscle surgery for management of hypotropia in monocular elevation deficiency type II

AIM

To assess the efficacy of vertical muscle surgery for management of hypotropia in monocular elevation deficiency (MED) type II. Knapp's is described as standard procedure for management of MED type II. However, it is not graded and has unpredictable amount of correction. Besides this, there is drift towards overcorrection with time and limitation of movements in extreme adduction and abduction. MED is a vertical misalignment for which vertical muscle surgery is also described but limited literature is available.

METHODS

Thirteen fresh cases of MED type II with hypotropia >20 PD and age >4 years were included in our interventional study. All cases underwent superior rectus resection and inferior rectus recession (vertical R&R) depending upon amount of preoperative deviation. Success was defined as hypotropia <5 PD at 1-year follow-up.

RESULTS

Twelve patients (92.30 %) were aligned to within 5 PD. Six patients (46.15 %) had gain in elevation. Bell's phenomenon was improved in six patients (46.15 %). There was no limitation in down gaze in any patient. None gained stereopsis.

CONCLUSION

Vertical R&R is a good alternative for MED type II with predictable amount of correction especially in patients with higher preoperative deviation. It spares horizontal muscles for correction of any associated horizontal deviation.