Glaucoma Screener
Jan 2018 - June 2019
This biomedical device spun out of my semester-long internship at the Biomedical Engineering and Technology Innovation Center, IIT Bombay in 2018 and was carried forward as my B.Tech project at the Symbiosis Institute of Technology in 2019 to develop and test the headgear-mounted ophthalmic device for reliable and rapid diagnosis of eye-related diseases such as glaucoma.
Team
Arvind Bhallamudi (Lead Design Engineer), Tapas Pandey (Electronics Engineer), Dr. Rupesh Ghyar (Guide), Dr. Nitin Khedkar (Guide), Dr. Amit Kumar Tiwari (Patent Lawyer)
Role
Conducted research and led the medical device design, engineering, prototyping and fabrication, working with the team to patent, and test and validate the device in trials.
Services
Mechanical Engineering
3D Printing
Rapid Prototyping
Machine Design
User Testing
Industrial Design
Current Scenario
Over 80 million people are affected by glaucoma worldwide. In this condition, the system for absorbing the intraocular fluid from the eye becomes clogged. It causes intraocular pressure (IOP) to build up, damaging the optic nerve and leading to vision loss and blindness. While there is no cure for this condition, it can be controlled by frequent check-ups if detected early and managed. Gold standard devices like Schiøtz tonometer require the aid of experienced clinicians, and are often invasive, time-consuming, and cumbersome.
Img.1 Goldmann Applanation Tonometer
Img.2 Schiotz Indentation Tonometer
Mechanism Design
The device developed in this work is based on research work that utilized a combination of indentation and applanation principle to measure IOP. It involves positioning the indenter such that it just touches the eyelid. Then it is moved forward to gently flatten the cornea through the eyelid to obtain the reaction pressure from the eye.
Fig.1 Device components.
Fig.2 Device exploded view and assembly.
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Fig.3 Sensing module mechanism design, cross sectional.
Prototyping
These versions improved ergonomics, assembly fittings and reduced size to make it portable and lightweight. To place the screening module accurately above both eyes of the patient, an indenter positioning system was needed, where the screening module can be fixed and used.
Img.3 Prototypes and iterations of screening module.
Img.4 FSR sensor, printed circuit board and LED.
Img.5 Initial tests for ergonomics and eye position.
Headgear Development
For anatomically different facial structures and sizes, concepts of a headgear system to stabilize positioning the indenter and standardize measurements were sketched out. The 3-axis slider where the screening module can be fixed using screw knobs was the most feasible and flexible.
Sketch.1 Concept sketches in three directions of headgear inspired by adjacent product applications.
Table.1 Comparative matrix for functions and criteria.
Sketch.2 Selected concept with three axis slider.
Fig.4 CAD assembly and render of the headgear and screening module system.
Simulation
A plot of stresses and displacement was generated for two of the key elements of the device – the indenter and the slots on the headgear frame. A nominal load of 1N was applied on the filleted edge of the slots from where the elastic band would be pulled. The maximum displacement is in the range of 10^(-3)mm which renders both parts safe to use.
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Fig.5 Exploded view of device assembly with parts and manufacturing processes.
Fig.6 Static simulation for checking stress-strain at elastic slot, spring, and indenter.
How to Use
Convenience in diagnosis is a key feature in this design. It requires no special training and allows users to get diagnosed at home or in large medical camps by healthcare workers with three simple steps. The device was successfully validated by the BETIC team measuring the IOP in over 50 patients, which corresponded to the values obtained using Goldmann tonometer - the standard in measurement.
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Fig.7 How to use the device in three steps: align sliders, fix screws, and rotate screw cap.
Multimedia and Communications Plan
Balancing creative writing with technical information was done in parallel with the assisting the design team with layouts, visual graphics, imagery and interactions. The communications strategy and website were refined, tested and launched in June 2024.
Conclusion
Positioned as an ophthalmic device for easy and rapid diagnosis of a disease that affects thousands each year. the design, engineering and findings of this study are published in Design for Tomorrow: Volume III, and an international patent published in the World Intellectual Property Organization.
Img.6,7 Working prototype, and testing.