This customer is a leading manufacturer of precision ophthalmic consumables and equipment. Based out of India, they support one of the largest eye-care systems in the world and serve geographies including Southeast Asia, Middle East and African regions. One of their existing products – Digital Vision Chart – had to be re-engineered from a FPGA based design to MPU embedded firmware based to enable flexibility and support extra features.
Embien worked with the customer, took up the complete responsibility of the development, reengineered the product, and helped them with setting up the product manufacturing. We addressed various challenges and exceeded the business objectives set for this development.
Digital Vision Chart
The design was expected to support multiple variants of the device with changes in the monitor dimensions and InfraRed remote integration. Also, it had to support multimedia playback and integrate with the hospital EMR system seamlessly.
Apart from the technical part, there were two primary challenges associated with this development. First is the product cost. As the Digital vision chart is sold for serving community clinics and hospitals, the pricing had to be as low as possible. Also, the market was a highly competitive one with any unqualified players driving the prices down. The second challenge is to support diverse geographies in accordance with the local regulatory compliance requirements and user interfaces.
Digital vision acuity chart or more commonly a Digital Vision Chart (DVC) is a device that holds digitized formats of commonly available visual acuity charts that are used to determine the visual acuity of the human eye. It replaces the traditional fixed test distance eye charts placed in the wall by an LCD/LED display of variable test distance settings with the same traditional chart rules. It incorporates accurate design of characters of different acuity scales with appropriate alignment according to the standards of various charts such as Snellen, ETDRS, LogMar, etc. Apart from the visual acuity charts, it also incorporates charts for child eye test, color blindness test, and other special-purpose charts.
Digital Vision Chart - Block Diagram
Our Turnkey product development team sprung into action in developing the product in accordance with the customer requirements. To support scaling of symbols, a scalable vector graphics library like OpenVG was preferred. Also, it needed to have multimedia capabilities to play H264 format videos. The embedded hardware team analyzed many available SBCs/SoMs in the market and zeroed in on a SBC that suits the technical requirements of the system as well as the costing needs. A small adapter card was designed to support some of the custom peripherals needed for this DVC product.
Our embedded OS and BSP team enabled drivers for the customer peripherals in the system and validated them. IR protocol support was enabled, and proper decoding logic were imported so that the remote-control inputs were obtained correctly. As multiple remote controls needed to be supported, the decoder was dynamically selected based on the device configuration. The team also developed a USB based firmware update process where the application can be updated with ease.
Our Embedded Application development team developed the DVC application with core functionalities in C and C++. Based on the configuration, the monitor dimensions, mount distance and mirrored effect are determined, and scaling factors calculated. With respect to the inputs from the remote, the vision scales are selected, and symbol size calculated. Using the OpenVG, these symbols were displayed based on the chart type being displayed like Snellen, ETDRS, LogMar, etc. The multimedia capabilities were enabled using OpenMax plugin integration and added as part of the application.
The Sparklet graphics library was used to support the user interface and menu navigation features. Multiple languages were supported including European languages like English, French, German, Spanish, Indian languages like Tamil, Kannada, Telugu, Malayalam, Hindi etc. and Right-to-left languages like Arabic, Hebrew etc. Both the charts and interface supported these languages to help crater to the global market.
Our mechanical design team designed a small metallic enclosure to place the boards and provided slots to connect the IR receiver. As there was a buzzer, suitable slots were given for the buzzer sound to propagate well. The design was strategically placed behind the COTS monitors so that it is not visible to the end user.
As the device was to be sold across multiple geographies, Embien proposed and followed the IEC 62304 – medical device software – software life cycle processes. All the necessary processes and tools were put into place before the development and followed stringently. We also supported our customer during the certification process. Our hardware was also compliant with IEC 60601-1 Electromagnetic Compatibility of Medical Devices, and we helped in the certification process as well.
The product was verified and validated by our Quality Assurance team. All kinds of testing like interface testing, load testing, memory profiling and UI testing were done to ensure the product can stand the test of time and multiple hands in the field. Post validation and verification, the product prototypes were manufactured and shared to customer for their validation. Once accepted, we transferred the complete technology transfer for them to continue with manufacturing.
Backed by our Medical device engineering expertise, we offered the customer some of the following benefits in the Digital Vision Chart development.
Currently the device is in the field over dozens of countries across thousands of locations. Even though the yearly numbers are low as 1000 to 2000, our low-cost design helped the customer stay ahead of the competition. Our reliable and certified medical software was very stable, avoiding costs associated with field issues.
This is a cap in our Turnkey Product development services team as it also contributed socially towards community healthcare. Our medical device engineering expertise to thank for!