Perceptions and use of computer-assisted surgery (CAS) in the orbit

Image-guided navigation in posterior orbital tumour surgery: a comparative cohort study

PURPOSE

The posterior orbit is a confined space, harbouring neurovascular structures, frequently distorted by tumours. Image-guided navigation (IGN) has the potential to allow accurate localisation of these lesions and structures, reducing collateral damage whilst achieving surgical objectives.

METHODS

We assessed the feasibility, effectiveness and safety of using an electromagnetic IGN for posterior orbital tumour surgery via a comparative cohort study. Outcomes from cases performed with IGN were compared with a retrospective cohort of similar cases performed without IGN, presenting a descriptive and statistical comparative analysis.

RESULTS

Both groups were similar in mean age, gender and tumour characteristics. IGN set-up and registration were consistently achieved without significant workflow disruption. In the IGN group, fewer lateral orbitotomies (6.7% IGN, 46% non-IGN), and more transcutaneous lid and transconjunctival incisions (93% IGN, 53% non-IGN) were performed (p = .009). The surgical objective was achieved in 100% of IGN cases, with no need for revision surgery (vs 23% revision surgery in non-IGN, p = .005). There was no statistically significant difference in surgical complications.

CONCLUSION

The use of IGN was feasible and integrated into the orbital surgery workflow to achieve surgical objectives more consistently and allowed the use of minimal access approaches. Future multicentre comparative studies are needed to explore the potential of this technology further.

Image-guided orbital surgery: a preclinical validation study using a high-resolution physical model

OBJECTIVE

Preclinical validation study to assess the feasibility and accuracy of electromagnetic image-guided systems (EM-IGS) in orbital surgery using high-fidelity physical orbital anatomy simulators.

METHODS

EM-IGS platform, clinical software, navigation instruments and reference system (StealthStation S8, Medtronic) were evaluated in a mock operating theatre at the Royal Victoria Eye and Ear Hospital, a tertiary academic hospital in Dublin, Ireland. Five high-resolution 3D-printed model skulls were created using CT scans of five anonymised patients with an orbital tumour that previously had a successful orbital biopsy or excision. The ability of ophthalmic surgeons to achieve satisfactory system registration in each model was assessed. Subsequently, navigational accuracy was recorded using defined anatomical landmarks as ground truth. Qualitative feedback on the system was also attained.

RESULTS

Three independent surgeons participated in the study, one junior trainee, one fellow and one consultant. Across models, more senior participants were able to achieve a smaller system-generated registration error in a fewer number of attempts. When assessing navigational accuracy, submillimetre accuracy was achieved for the majority of points (16 landmarks per model, per participant). Qualitative surgeon feedback suggested acceptability of the technology, although interference from mobile phones near the operative field was noted.

CONCLUSION

This study suggests the feasibility and accuracy of EM-IGS in a preclinical validation study for orbital surgery using patient specific 3D-printed skulls. This preclinical study provides the foundation for clinical studies to explore the safety and effectiveness of this technology.

Endoscope-navigation-assisted orbital decompression for graves' orbitopathy

PURPOSE

To compare the surgical outcomes of endoscope-navigation (EN)-assisted orbital decompression and non-EN-assisted orbital decompression for Graves' orbitopathy (GO) and to assess the potential clinical advantage of EN in orbital decompression surgery.

METHODS

This retrospective cohort study was performed on 227 orbits of 147 GO patients who underwent EN-assisted orbital decompression (185 orbits) or non-EN-assisted orbital decompression (42 orbits). Assessment included proptosis reduction, best-corrected visual acuity (BCVA), diplopia, ocular restriction and surgical complications.

RESULTS

The proptosis reduction in the EN group was 0.9 mm greater than that in the non-EN group in the entire cohort (p  =  0.004) and 1.0 mm greater than that in the non-EN group in the propensity score matching cohort (p  =  0.025) at 2 years postoperatively. In all, 78.2% of orbits with sight-threatening GO in the EN group and 52.6% of orbits in the non-EN group showed BCVA improvement (p  =  0.026). The proportion of patients with improvement in diplopia was significantly greater in the EN group than in the non-EN group (p  =  0.026).

CONCLUSIONS

EN offers anatomical localization and deep-seated tissue visualization in orbital decompression and significantly improves the surgical outcomes for GO.

Use of computer-assisted surgery in the orbit

PURPOSE

To present the application of computer-assisted surgery (CAS) in pre-operative planning, intra-operative navigation, and post-operative assessment as an adjunct tool in orbital surgery.

METHODS

An IRB-approved, retrospective review was performed to identify patients who had undergone orbital surgery by a single surgeon from July 2013 to December 2019 with attention to pre-operative virtual surgical planning, intra-operative navigation, and post-operative assessment. The reasons and methods of CAS use were classified.

RESULTS

The use of computer-assisted technologies was identified in 91 cases out of 464 orbital surgeries (19.6%). This included 23 (25.3%) orbital decompression surgeries, 39 (42.9%) fracture repairs, and 25 (27.5%) orbital tumors. In all cases, pre-, intra-, and post-operative CAS allowed for increased operative efficiency and safety with good outcomes.

CONCLUSIONS

Use of CAS in orbital surgery can allow for complex radiographic analysis and in select cases is a great tool to add to the orbital surgeon's armamentarium.