Clinical Role of Swept Source Anterior Segment Optical Coherence Tomography in Strabismus Re-Operation with Lost Surgical Details

Management of traumatic incomplete lacerating rectus muscle injuries using multimodal imaging approach (ASOCT and CT/MRI)

Purpose: To describe the pathophysiology, importance of multimodal imaging approach, and the clinical outcomes of incomplete lacerating rectus muscle injuries. Methods: A retrospective review was conducted to identify patients with ocular deviation secondary to rectus muscle injuries. Between 2019 and 2022, a total of 30 patients were identified, amongst whom eleven patients had incompletely lacerated rectus muscles (secondary to penetrating adnexal trauma and sino-orbital surgeries). Patients' demography, nature of injury, computed tomography/magnetic resonance imaging, anterior segment optical coherence tomography features, intra-operative findings, and post-operative outcomes were reviewed. Results: The mean age of 11 patients was 31.36 ± 14.38 years. All patients had external trauma which severed the muscle in its anterior portion. Five patients had isolated inferior rectus muscle injury (45.45%), three had inferior and medial rectus muscle injuries together (27.27%), two had isolated lateral rectus muscle injury (18.18%), and one remaining patient had isolated medial rectus muscle injury (9.05%). In ten patients (90.90%) CT/MRI revealed features suggestive of muscle injury, however details with respect to muscle insertion and scleral course were lacking. In this difficult scenario, ASOCT filled these lacunae in nearly 90% of the patients by providing surgically useful details. Moreover, when CT/MRI-ASOCT imaging features were combined, the management and outcomes were even more predictable. Conclusions: Penetrating rectus muscle injuries can be better identified as incompletely lacerated muscle using multimodal imaging approach. This simple image correlation process customizes the treatment approach and hence the clinical outcomes.

Study 3: Anterior segment optical coherence tomography-guided surgical approach in slipped medial rectus muscle

Purpose

To discuss the novel swept-source anterior segment optical coherence tomography (SS-ASOCT)-guided surgical approach in slipped medial rectus muscles.

Methods

Prospectively (between February 2020 and July 2022), six patients with a clinical suspicion of slipped medial rectus muscle were recruited. After complete ophthalmic and orthoptic evaluation, the missing medial rectus muscle is screened using Anterior Segment Optical Coherence Tomography (ASOCT). In presence of a traceable muscle, its morphology, depth, and distance from a fixed anatomical landmarks were noted; in its absence, the status of other recti was noted. Intraoperatively, the features were confirmed and the intended intervention was performed.

Results

The mean age of six patients was 25.66 ± 9.72 years, two with surgical trauma and four with penetrating trauma (66.66%). In five patients, the ASOCT traced the slipped medial rectus muscle successfully (83.33%); intraoperatively, the same was confirmed (within 1-2 millimeters) with favorable outcomes. ASOCT made a significant contribution in all subjects by reducing the number of interventions and muscle surgeries.

Conclusions

In eyes with slipped medial rectus muscle, especially those which are within a finite distance from the angle can be traced using ASOCT. This approach impacts the outcomes in many ways.

Defining the Clinical Role of Swept-Source Anterior Segment Optical Coherence Tomography in Eyes Undergoing Strabismus Surgery

Purpose

To describe the clinical role of swept-source anterior segment optical coherence tomography in extraocular muscle imaging in various strabismic conditions.

Study Design

Prospective observational study.

Participants

A total of 1104 extraocular muscles of 150 subjects were imaged. Normal eyes (640 muscles), eyes undergoing re-operation (240 muscles), paralytic strabismic eyes (16 muscles), non-paralytic strabismic eyes (20 muscles), post-traumatic strabismic eyes (64 muscles), eyes with thyroid disease (64 muscles), and other atypical cases (60 muscles) were imaged. In all cases, up to four recti muscles were evaluated in a given eye depending on the need.

Results

The mean age was 38.15 ± 16.25 years. Overall, muscle insertion was identified in over 90% of the subjects. Apart from normal muscles (n = 860, 93.68%), the location was identified in previously operated eyes (n = 54, 90%), in traumatic muscle slippage (n = 2, 11.11%), in ocular coat ectasia (n = 11, 91.66%), in thyroid muscle hypertrophy, in operated scleral fixated intraocular lens with strabismus, and other challenging cases. In all circumstances, clinically useful information was obtained from the anterior 4–14 millimetres of the rectus muscle, which in turn helped in active surgical planning and overall management.

Conclusion

The SS-ASOCT with its wider and deeper scanning abilities was able to locate the extraocular muscle insertion in a variety of strabismic conditions. Therefore, this tool can be used in the preoperative periods for optimal surgical planning and management.