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According to the World Health Organisation (WHO) 285 million people in the world were visually impaired in June 2012.It is estimated that 80% of these people’s impairments could be either avoided or cured and some of can be corrected by surgery.
Vitreoretinal surgery is a specific type of ophthalmological micro-surgery that requires surgical precision to repair ailments including retinal detachment, vitreous haemmorhage, retinal cannulation, macular pucker and diabetic retinopathy. The major issues limiting success in vitroretinal surgery include the ability of the surgeon to manipulate the surgical tool precisely within the physical constraints they have at incision point, their ability to visualize or perceive the physical parameters in which they have to operate, physiological hand tremors and their ability to be able to sense the amount of force they are using. This is particularly difficult due to the micro nature of the surgery and their ability to see and reach the affected area, which creates a constrained environment, which the surgeon has to work with.
This type of surgery is the most technically demanding of all ophthalmological surgeries, and the risks to patients are high due to the delicacy of the operation, the inability of the cells to regenerate if they are injured, the limitations of being able to directly visualise the affected area and the lack of sensory feedback. For these reasons, the opportunity to improve how vitreoretinal surgery can be done is welcomed by both the medical field and patients alike.
In recent years, the use of robotic manipulators has been explored in carrying out micro-scale, minimally invasive surgeries, with a view to improving precision and stability. However these have been constrained where a computer control or a rigid link mechanism (which is constructed from rigid links or bars and mechanical joints)has been used for tool movement. Computer controlled methods are considered to be less safe since error by the controller could lead to the tools going beyond the designated area of the operation, which can be dangerous for the patient. On the other hand, rigid link mechanismshave resulted in mechanical errors due to frictional losses and wear and tear, which in turn impacts precision of motion.
Furthermore, precision surgery requires additional restraints on surgical tools (compared to other surgeries) as a minute error can lead to irreparable damage of surrounding tissues or organs. This is not acceptable in surgeries such as vitroretinal surgery, where a high degree of accuracy and stability is required. One small error in this type of surgery can result in irreparable damage to the patient’s sight.
Rupesh S Bobade of IITB-Monash Research Academy is researching a novel approach to enable minimal invasiveness of vitreoretinal surgery using compliant mechanisms with a mechanical remote centre. This means that during surgery the surgeon holds the tool which passes through the incision and is then capable of manipulating the tool inside the incision area. The ability to do this is achieved by the compliant mechanism.
The compliant mechanism (or flexible links mechanism) means that it has the ability to be flexible, or enable compliant movement which makes it easier to use and mimic the surgeons feel. The mechanical remote centre is created by a novel design using this flexible links mechanism (for which a patent is pending). The surgeon using the tool (which is held by the flexible links mechanism) is able to rotate it around the centre of an arc, which is located at a distance. This is effectively a remote centre, that enables the surgeon to manipulate the tool, which is then performing the operation inside the incision. This is exactly the same way minimally invasive surgeries are currently performed, but now the feel and precision will be improved by Bobade’s invention.
Bobade’s research has designed this robotic mechanism so that it is placed in between the surgeon’s hand and the sclera of the patient’s eye ball, so that it can preserve the way the surgeon conducts the surgery. The mechanism has also been designed to be light-weight, frictionless and easy to control, enabling the surgical feel to be preserved whilst quelling hand tremors.
The mechanism’s algorithms take into account the constraints of the surgery (such as the space in which it can be performed) along with the surgical requirements, which can then be used to “assist” the surgeon in performing the operation with less error. This novel robotic mechanism also removes the need for expensive force sensors that have been used in other designs, and it is anticipated to have a minimal cost of fabrication.
Once completed, the mechanism will enable a surgeon to conduct the surgery with minimal hand tremors, a greater ability to work on the affected area and preserve the surgical feel of the procedure. It may even be possible for a less skilled surgeon to conduct such surgeries in the future.
The mechanism would also be able to be used to test various surgical scenarios and develop control algorithms which would allow the surgery to be carried out more efficiently. Similar prototypes could then be used across other areas of medicine and across surgical fields.
In addition, the research may have applicability beyond medical fields, and can be used in other areas where techniques for working within constrained conditions are required such as for precision assembly of micro electrical and mechanical components. This will require system dynamics and underlying principles to be inferred, but will then provide new methods of performing these tasks.
The IITB-Monash Research Academy is a Joint Venture between the IIT Bombay, India and Monash University, Australia. Opened in 2008, the IITB-Monash Research Academy operates a graduate research program located in Mumbai that aims at enhancing research collaborations between Australia and India. Students study for a dually-badged PhD from both institutions, and spend time during their research in both India and Australia.
Bobade comments “Vision is one of the most precious gifts.Unfortunately,this gift is lost due to old age or accident. Whilst there have been many good developments in medical science in recent years, there are some areas where the involvement of technology or engineering can take medical science to a higher level. This project will be another milestone for medical science and the world of engineering as it will effectively overcome the limitations of micro-scale minimal invasive surgeries and improve their success rates. On a personal level, this research gives me the opportunity to serve society and help some individuals regain the gift of sight.”
The research has been conducted under the guidance of Professor P S Gandhi from IIT Bombay and Dr Chao Chen of Monash University, and in consultation with surgeons from the Aditya Jyot Eye Hospital to ensure that the constraints and specific requirements of the operating theatre are taken into account in its design. This collaboration will also ensure that the final product has commercial applicablility. The invention is protected under apatent.
For now, Bobade’s research will help more people see again, but in the future its application could be revolutionary in medical fields requiring micro-precision. Who knows just how many lives will be enhanced or saved as a result of this ground-breaking research.
Research Scholar: Rupesh S Bobade, IITB-Monash Research Academy
Project Title: Development of a novel 4-DOF compliant robotic assist for vietreoretinal surgery
Supervisors: Professor P S Gandhi and Dr Chao Chen
Contact Details: firstname.lastname@example.org
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The above story was written by Ms Rakhee Ghelani based on inputs from the research student and IITB-Monash Research Academy. Copyright IITB-Monash Research Academy.