Glaucoma Screener
B.Tech Final Project | Symbiosis International University 2019 | International Patent WIPO 2020
Awarded Most Distinguished Paper at the International Conference in Research into Design 2020
Context
In of 65 million people affected by glaucoma worldwide, over 3 million turned permanently blind. While there is no cure for this condition, it can be controlled by frequent check-ups if detected early.
Gold standard devices like Schiøtz tonometer require the aid of experienced clinicians.
These machines are invasive, uncomfortable and cumbersome.
Device Mechanism Design
In glaucoma, the system for absorbing the intraocular fluid from the eye becomes clogged. This causes intraocular pressure (IOP) to build up, damaging the optic nerve and leading to vision loss. Using applanation tonometry, the cornea is indented and IOP is determined by measuring the reaction force.
Imbert Fick’s principle states that the pressure inside an ideal dry, thin-walled sphere equals the force necessary to flatten its surface divided by the area of flattening (P = F/A). From existing research, the maximum pressure for a healthy eye was found to be 2253 Pa (P) at a standard indentation of 4mm. The enclosure components are designed such that the clinician can simply rotate the cap by 360 degrees to applanate the cornea. Arrows are inscribed on the parts to mark completion of one revolution. An LED flashes when the applied force crosses this threshold, indicating a risk of glaucoma.
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Different device enclosures were designed, modelled and 3D printed to find a suitable form. Through this evolution, I improved ergonomics, component fittings and reduced overall size. Appropriate holes were given for LED visibility and access to calibration screw. The final enclosure was integrated with 3M goggles after some modifications.
After assembling the device, it was tested on glaucoma patients at a medical camp.
It was done in comparison to Goldman Applanation Tonometer, the gold standard in IOP measurement, and the results were found to be accurate. One reflection was that for different face structures and sizes, there was a need for a system to position the indenter accurately above both eyes of the patient.
Indenter Positioning Concepts
Three main directions were explored to create the indenter positioning system. The final concept can be fastened around the head with a three-way elastic. It contains a slider system where a screening module for glaucoma can be positioned and fixed.
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Headgear Assembly and Simulation
With the headgear in CAD, the screening module and related components are integrated with the indenter positioning system. Developments include static simulation validation on crucial components of the device – elastic slot, spring and indenter.
Usability and Interaction
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. The device can be fastened around the head with a three-way elastic. After that, three simple steps are followed, as shown below.
The glaucoma screener is positioned as an ophthalmic device for affordable and convenient diagnosis of an eye disease that affects thousands every year.
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