ObjectiveProcuring an affordable eye mount that can stabilise a cadaveric eye and simulate a patient’s normal facial contours represents an ongoing challenge in the ophthalmology simulation wet lab, with notable limitations to all currently available commercial options. This project uses computer-assisted design and three-dimensional (3D)-printing techniques to tackle these challenges for ophthalmologic surgical training.Methods and AnalysisProof-of-concept study. Using Autodesk Fusion 360, we designed and 3D-printed a modular device that consists of 11 pieces forming a head structure. Standard OR tubing and syringes were adapted to create an adjustable-suction system to affix cadaveric eyes. Further modular inserts were customised to house non-cadaveric simulation eyes.ResultsThree-dimensional eye mount for procedures in ophthalmology (TEMPO) reliably fixed a cadaveric eye in stable position throughout surgical manipulation. Trainees were able to drape and practice appropriate hand positioning while corneal suturing. Overall, this model was affordable, at a cost of approximately $C200 to print. The modular nature renders individual pieces convenient for replacement and customisable to simulate regional anatomical variation and accommodate non-cadaveric eyes.ConclusionsTEMPO represents an affordable, high-fidelity alternative to existing commercially available eye mounts. It reliably fixates cadaveric and simulation eyes and provides an enhanced surgical training experience by way of its realistic facial contours. It is released as an open-source computer-aided design file, customisable to interested trainees with appropriate software and 3D-printing capacity.
Many vital motor behaviors – including locomotion, swallowing, and breathing – appear to be dependent upon the activity of and coordination between multiple endogenously rhythmogenic nuclei, or neural oscillators. Much as the functional development of sensory circuits is shaped during maturation, we hypothesized that coordination of oscillators involved in motor control may likewise be maturation‐dependent, i.e., coupling and coordination between oscillators change over development. We tested this hypothesis using the bullfrog isolated brainstem preparation to study the metamorphic transition of ventilatory motor patterns from early rhythmic buccal (water) ventilation in the tadpole to the mature pattern of rhythmic buccal and lung (air) ventilation in the adult. Spatially distinct oscillators drive buccal and lung bursts in the isolated brainstem; we found these oscillators to be active but functionally uncoupled in the tadpole. Over the course of metamorphosis, the rhythms produced by the buccal and lung oscillators become increasingly tightly coordinated. These changes parallel the progression of structural and behavioral changes in the animal, with adult levels of coupling arising by the metamorphic stage (forelimb eruption). These findings suggest that oscillator coupling undergoes a maturation process similar to the refinement of sensory circuits over development.
How the neuronal control of air breathing evolved is unknown. Brainstem circuits controlling breathing have only been investigated in a small handful of extant vertebrates. This makes an evolutionary analysis challenging.In the frog, we have found evidence for three areas involved in respiratory rhythm generation, each with distinct pharmacologies: the buccal area in rhombomere 7 as well as both lung burst priming and lung burst power stroke regions situated in rhombomeres 4‐5. We have long assumed that circuits generating air breathing in mammals and frogs are homologous, evolving from a common ancestry. However, there are some inconsistencies with this assumption. The primary inspiratory oscillator in mammals, the PreBötzinger Complex (PreBötC), is located in rhombomere 7‐‐the same rhombomere as the frog buccal area‐‐and the rhythms produced by buccal and PreBötC are stubbornly independent of CO2. In comparison, like pre‐inspiratory/expiratory activity in mammals, the lung bursts in the frog are highly CO2 sensitive, and both originate in rhombomere 4‐5.These data suggest that we may have to turn our previous hypothesis that the frog lung area and PreBötC are homologous on its head and consider the possibility that the mammalian PreBötC evolved from a fish oscillator used for water‐breathing. Until more studies on non‐mammalian vertebrates are performed any hypothesis on the evolution of air breathing is but a work in progress, and with so little data currently available, further oscillations are likely.This work was funded by NSERC.
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