Designing a portable, hand-held probe for retinal imaging

• Main Author: Chua, Nigel Yue Zhuan
• Other Authors: Murukeshan Vadakke Matham
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/158641
• Institution: Nanyang Technological University

This project aims to create a portable handheld probe to capture retinal images to identify ocular diseases, primarily focusing on the detection on cataracts. In this report, a literature review of cataract and its prevalence around the world is discussed. Several retinal and fundus imaging methods are also reviewed for their advantages and disadvantages. Through this comparison, fundus photography is selected as the approach that the proposed handheld probe would adopt for the image capturing procedure. This is due to the capability of using small and lightweight components in this method and its ability easily record retinal images that can be reviewed later by clinicians. A preliminary investigation is conducted using an existing prototype probe, with the objective of the investigation being the familiarisation of the equipment, image capturing procedures and identification of key variables that needs to be optimised to produce high quality images of the retina. Subsequently, variations in parameters are made to improve the quality of images. These iterations include the positioning of the light source, optimizing the focal distance of the camera and developing techniques to reduce the strong specular reflections from the eye. Multiple variations are investigated before an optimized design is finalised to maximise strengths of each variant. The final probe prototype is 3D printed and custom written software is incorporated into the microcontroller that controls the probe operations such as image capturing and flashing of the light source for red reflex imaging. Images from a phantom eye model and ex-vivo porcine eye samples are captured, and the results are analysed. In the final section of the report, future work directions are proposed to further improve the effectiveness of the probe.