A modular and adjustable ptosis crutch as a non-surgical, low cost solution for elevating the upper eyelid in Myasthenia Gravis

Abstract

Myasthenia Gravis (MG) is an autoimmune disorder that affects the neuromuscular junction. MG is characterised by the fatigable weakness of skeletal muscles, commonly affecting the eye and facial muscles. Africans with MG, particularly juveniles, are more likely to develop treatment-resistance of their ocular muscles, including severe blepharoptosis. Blepharoptosis, or ptosis, describes the condition of a drooping upper eyelid(s). Surgical correction of ptosis is often contraindicated in MG patients. In these cases, a non-surgical solution to elevate the ptotic eyelid above the visual axis is required. Objective: To design a ptosis crutch to elevate the ptotic eyelid(s) of MG patients. The crutch should be low cost, modular and adjustable in nature. Method: A bottom-up approach was followed for the design of the ptosis crutch. The requirements were defined according to patient, clinician and designer specifications. It underwent numerous iterations before the final design was manufactured, using 3D printing. 87 design failures were observed before the final design was realised. It was the design, test, fail, redesign cycle that lead to the discovery of a device that satisfied the requirements. Results: The ptosis crutch attaches to the superior border of the spectacle frame and is adjustable along the x, y and z-axes to cater for the inter-individual variability of horizontal eye position, globe projection and the eyelid elevation required. Conclusion: MG patient feedback on the ptosis crutch has shown a promising outcome for the device. Future work will include obtaining long term user feedback on the ptosis crutch.