Computer-aided fixation detection using retinal birefringence in multi-modal ophthalmic systems: Computer, electronics, algorithms

• Published in: Computers in biology and medicine Vol. 119; p. 103672
• Main Author: Gramatikov, Boris I.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.04.2020; Elsevier Limited
• Subjects: Algorithms; Birefringence; Circuits; Combined retinal imaging systems; Data acquisition; Decision making; Diabetic retinopathy; Diagnostic systems; Eye; Eye movements; Fixation; Fovea; Image acquisition; Image detection; Lasers; Localization; Medical imaging; Medical screening; Methods; Noise; Optical polarization; Optics; Opto-mechanics; Pediatrics; Polarization; Polarization-sensitive optical imaging systems; Polarized light; Real-time fixation monitoring; Retina; Retinal images; Robustness; Scanning; Subsystems; Target acquisition; Real-time fixation monitoring; Birefringence; Polarization-sensitive optical imaging systems; Combined retinal imaging systems
• ISSN: 0010-4825; 1879-0534; 1879-0534
• DOI: 10.1016/j.compbiomed.2020.103672

Many diagnostic and some therapeutic ophthalmic devices require a reliable complementing method to track the direction of gaze or just to validate fixation of the eye on a presented target. This would allow acquisition of artefact-free robust images of the fovea and the surrounding macula. So far, there have been only few attempts to provide fast and dependable fixation information to an optical imaging system in real time, to guide image acquisition. The author's lab has developed several instruments that detect the location of the fovea using retinal birefringence scanning (RBS), proven to be very effective. Here, an RBS-based fixation detection subsystem is proposed, designed to operate conjointly with a number of ophthalmic imaging technologies. Combining RBS with such technologies is not trivial, because RBS uses polarized light and polarization-sensitive optics, while most other modalities don't. The polarization optics was optimized by means of enhanced computer modeling. Both the electronic hardware and the software were designed for fast and reliable performance. Because many retinal imaging systems are used in pediatric settings, extensive audio-visual circuitry was employed for efficient attention/fixation attraction. The optomechanics has been optimized for robust data acquisition. This computer-aided conjoint system employs true anatomical information from the back of the eye and needs no calibration. The prototype instrument uses a decision-making logic based on four frequencies generated during scanning. The results reveal the applicability of RBS as an adjunct fixation monitoring modality, showing promise to remove the limitation imposed by eye movements upon advanced ophthalmic imaging technologies. •Ophthalmic devices often require a complementing method to monitor fixation.•Retinal birefringence scanning can help to guide fundus imaging instruments.•Computer modeling helps in the design of polarization-sensitive systems.•Audio-visual attention attraction improves reliability in pediatric imaging devices.•Windows-based system optimized for speed using special hardware and software.