Applications of three-dimensional printing in orbital diseases and disorders

Late patient-fitted total orbital reconstruction for facial gunshot wound sequelae

Late reconstructions of gunshot wounds (GSWs) in the orbital area are a true challenge to the oral and maxillofacial surgeon. Usually, the wall defects are large in size and commonly present loss of orbital volume, which can cause ocular dystopia. The only exceptions are when there is an explosion of the orbital walls-that is, blow-out fractures. We encountered a patient with a two-year sequelae after GSW in the face that caused the destructed orbit to have a 2.5 bigger size than the contralateral orbit, requiring meticulous planning of a patient-specific implant (PSI) to correctly reconstruct the orbit volume and bone projection. The PSI was developed using titanium and it had three pieces that could reconstruct all four walls of the orbit. After surgery, the patient regained orbital volume and malar projection, allowing him to benefit from facial symmetry. The PSI can be used to reconstruct all the orbital walls in cases of complex bone defects.

Personalized Medicine Workflow in Post-Traumatic Orbital Reconstruction

Restoration of the orbit is the first and most predictable step in the surgical treatment of orbital fractures. Orbital reconstruction is keyhole surgery performed in a confined space. A technology-supported workflow called computer-assisted surgery (CAS) has become the standard for complex orbital traumatology in many hospitals. CAS technology has catalyzed the incorporation of personalized medicine in orbital reconstruction. The complete workflow consists of diagnostics, planning, surgery and evaluation. Advanced diagnostics and virtual surgical planning are techniques utilized in the preoperative phase to optimally prepare for surgery and adapt the treatment to the patient. Further personalization of the treatment is possible if reconstruction is performed with a patient-specific implant and several design options are available to tailor the implant to individual needs. Intraoperatively, visual appraisal is used to assess the obtained implant position. Surgical navigation, intraoperative imaging, and specific PSI design options are able to enhance feedback in the CAS workflow. Evaluation of the surgical result can be performed both qualitatively and quantitatively. Throughout the entire workflow, the concepts of CAS and personalized medicine are intertwined. A combination of the techniques may be applied in order to achieve the most optimal clinical outcome. The goal of this article is to provide a complete overview of the workflow for post-traumatic orbital reconstruction, with an in-depth description of the available personalization and CAS options.

[3D modeling for planning of minimally invasive approach to the orbit]

OBJECTIVE

To demonstrate own experience in 3D modeling for planning of minimally invasive approach to the orbit and anterior skull base.

MATERIAL AND METHODS

A 17-year-old patient admitted to the Department of Pediatric Neurosurgery with complaints of decreased visual acuity of the left eye, lacrimation and exophthalmos. MRI revealed a tumor of the left orbit. We have preoperatively modeled frontoorbital region, anterior skull, as well as eyeball and tumor within the same model. Considering young age and potentially favorable prognosis of disease, we preferred a minimally invasive intervention (microsurgical resection of tumor through minimally invasive frontoorbital access).

RESULTS

Total resection of tumor was followed by examination of anterior skull base. There was postoperative regression of visual disturbances, lacrimation and exophthalmos. Sutures were removed after 5 days, and the patient was discharged.

CONCLUSION

Minimally invasive frontoorbital access is adequate for approach to the orbit, anterior and middle cranial fossa, adequate resection of orbital tumor and examination of anterior skull base. 3D modeling is an additional preoperative tool to improve the quality of preoperative planning and facilitate intraoperative navigation.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

Critical appraisal of patient-specific implants for secondary post-traumatic orbital reconstruction

In orbital reconstruction, a patient-specific implant (PSI) may provide accurate reconstruction in complex cases, since the design can be tailored to the anatomy. Several design options may be embedded, for ease of positioning and precision of reconstruction. This study describes a cohort of 22 patients treated for secondary orbital reconstruction with a PSI; one patient received two PSI. The preoperative clinical characteristics and implant design options used are presented. When compared to preoperative characteristics, the postoperative clinical outcomes showed significant improvements in terms of enophthalmos (P < 0.001), diplopia (P < 0.001), and hypoglobus (P = 0.002). The implant position in all previous reconstructions was considered inadequate. Quantitative analysis after PSI reconstruction showed accurate positioning of the implant, with small median and 90th percentile deviations (roll: median 1.3°, 90th percentile 4.6°; pitch: median 1.4°, 90th percentile 3.9°; yaw: median 1.0°, 90th percentile 4.4°; translation: median 1.4 mm, 90th percentile 2.7 mm). Rim support proved to be a significant predictor of roll and rim extension for yaw. No significant relationship between design options or PSI position and clinical outcomes could be established. The results of this study show the benefits of PSI for the clinical outcomes in a large cohort of secondary post-traumatic orbital reconstructions.

Technological Integration of Virtual Surgical Planning, Surgical Navigation, Endoscopic Support and Patient-Specific Implant in Orbital Trauma

Currently, we have different technologies and techniques that improve the results in orbital trauma. However, there are few studies that study the technological integration in orbital trauma and the synergism of all the techniques. For this reason, the objective of this case is to illustrate the management of orbital trauma by integrating endoscopic support, virtual surgical navigation, patient-specific implant, virtual surgical planning in the management of a sequel due to insufficient reconstruction of orbital volume.

Three-dimensional design of a geometric model for an ocular prosthesis in ex vivo anophthalmic socket models

PURPOSE

Fitting a customized ocular prosthesis for anophthalmic patients entails an artisanal labour-exhausting process and is standardly based on impression moulding of the socket, which may be anatomically inaccurate. The objective of the study was to design an impression-free socket mould with three-dimensional (3D) technology.

METHODS

The ex vivo anophthalmic socket models included one silicone, one fresh pig cadaver head and three fresh-frozen human cadaver heads. After intra-socket application with iodine substance, five observers obtained eighteen low-dose cone beam computed tomography (CBCT) scans and one observer one high-dose CBCT scan of each model. The observers designed non-impression 3D moulds of the socket with 3D software. For the human cadaver sockets 3D geometric models of the ocular prosthesis were rendered from the 3D mould of the socket and the mirrored cornea of the contralateral eye.

RESULTS

The posterior surface of the 3D mould was highly accurate, with a mean absolute deviation of 0.28 mm, 0.53 mm, 0.37 mm and mean upper deviation of 0.53 mm, 0.86 mm, 1.17 mm, respectively, for the phantom, pig and human model. The intra- and interobserver repeatability and reproducibility of the 3D moulds and designs was good (<0.35 mm). The largest variation in the 3D geometric model was found at the junction of the 3D mould and mirrored cornea.

CONCLUSION

3D design of an impression-free geometric model for an ocular prosthesis with low-dose CBCT is highly accurate in ex vivo anophthalmic socket models. This novel method is a critical step towards the manufacturing of 3D printed ocular prostheses and requires validation in anophthalmic patients.

Orbital exenteration: an updated review with perspectives

Orbital exenteration is a radical and disfiguring surgery mainly performed in specialized tertiary care centers. Orbital exenteration has long been considered the treatment of choice for managing periocular tumors invading the orbit or primary orbital malignancies. Over the past decades, attention has been directed toward reducing the perioperative morbidity by developing new surgical devices and new strategies and promoting cosmetic rehabilitation by providing adequate facial prostheses. Despite these advances, several studies have questioned the role of orbital exenteration in improving overall survival. The last decade has been marked by the emergence of a new paradigm: the "eye-sparing" strategies based on conservative surgery with or without adjuvant radiotherapy and/or targeted therapies and immunotherapies. We summarize the data on orbital exenteration, including epidemiology, etiologies, use of surgical ablative and reconstructive techniques, complications, outcomes, and the related controversies.

Surgical Outcomes of Orbital Fracture Reconstruction Using Patient-Specific Implants

PURPOSE

Patient-specific implants (PSIs) are known to yield reliable outcomes in orbital wall fracture reconstruction (high precision, smoother operating techniques, and shorter surgical duration). This study analyzed the surgical error and clinical and esthetic outcomes of orbital reconstructions with PSIs.

METHODS

This ambispective cohort study enrolled patients who underwent orbital reconstruction using PSIs between October 2016 and January 2018. The study end points were surgical error, indication and duration of surgery, long-term sequelae, revision surgeries, and surgical complications. Surgical error was analyzed by superimposing the postoperative implant position onto the preoperative virtual plan. Both qualitative (heat map) and quantitative (distance) measurements were obtained.

RESULTS

Three patients were enrolled prospectively, and 23 were enrolled retrospectively. Indications for surgery were defect size (25 patients), diplopia (10 patients), impaired eye motility (4 patients), and significant enophthalmos (6 patients). At the last patient visit, there were 5 cases of diplopia, 1 case of exophthalmos, and 6 cases of slight enophthalmos of incremental degree. In terms of surgical error, a mean distance of 0.6 mm (95% confidence interval, 0.49 to 0.76), with a mean maximal distance of 3.4 mm (95% confidence interval, 2.79 to 4.02), was noted. No revision surgery was necessary. Lid malposition complications were not observed. However, 1 case each of symblepharon and scleral show were observed. No time-saving component was observed.

CONCLUSIONS

PSI use in orbital reconstruction guarantees a preplanned 3-dimensional anatomical shape with a mean surgical error of just 0.6 mm. Our clinical results were similar to those of other protocols; however, warranting a complex 3-dimensional anatomical shape also in large orbital fractures with a low mean surgical error is feasible by using PSIs.

3D Printing and NIR Fluorescence Imaging Techniques for the Fabrication of Implants

Three-dimensional (3D) printing technology holds great potential to fabricate complex constructs in the field of regenerative medicine. Researchers in the surgical fields have used 3D printing techniques and their associated biomaterials for education, training, consultation, organ transplantation, plastic surgery, surgical planning, dentures, and more. In addition, the universal utilization of 3D printing techniques enables researchers to exploit different types of hardware and software in, for example, the surgical fields. To realize the 3D-printed structures to implant them in the body and tissue regeneration, it is important to understand 3D printing technology and its enabling technologies. This paper concisely reviews 3D printing techniques in terms of hardware, software, and materials with a focus on surgery. In addition, it reviews bioprinting technology and a non-invasive monitoring method using near-infrared (NIR) fluorescence, with special attention to the 3D-bioprinted tissue constructs. NIR fluorescence imaging applied to 3D printing technology can play a significant role in monitoring the therapeutic efficacy of 3D structures for clinical implants. Consequently, these techniques can provide individually customized products and improve the treatment outcome of surgeries.