Imaging the human retina in-vivo plays a very important role in diagnosing eye and systemic diseases. Accurate and early diagnosis gives the patient better chances of not losing their sight - on average 100 people are registered blind or partially sighted every day in the UK, but over 50 of these cases could be prevented with the state-of-the-art in disease treatment already available if diagnosed in time. Furthermore, the incidence of many eye diseases (lat. Caecitudo) such as age-related macular degeneration and glaucoma increases with age. Therefore, in an ageing society, extensive and accurate screening of the population is required to increase the quality of life of many and reduce the cost burden of public and private health systems that need to cater for the blind. Scientists at the City, University of London (CITY UL) developed an optically simple, potentially inexpensive device for extensive screening of the population for eye disease.

Current retinal imaging technology falls in 2 categories, basic ʻconventionalʼ imaging techniques (such as the hand-held ophthalmoscope or fundus camera) that have very limited diagnostic capability owing to their inability to image individual retinal layers separately, and advanced retinal imaging systems (namely Scanning Laser Ophthalmoscopy and Optical Coherence Tomography) that have powerful diagnostic capabilities owing to their 3-dimensional imaging. The latter group are not widespread though and cannot be used in wide population screening.

The technique proposed here, Structured Illumination Ophthalmoscopy (SIO) which is derived from a technique from microscopy, fills the gap between these 2 extremes and can potentially lead to a device that has the 3D imaging characteristics of the advanced systems without their drawbacks, namely distortion, image noise, high light levels, as well as cost and size.

This is possible because the technique relies on a widefield illumination system (unlike the advanced systems that scan the retina point-by-point). The novelty lies in giving ‘structure’ to the illumination, and with the choice of the correct patterns, individual retinal layers can be imaged. Therefore, the optically simple, potentially inexpensive device with the highest diagnostic capabilities is the kind of tool required for extensive screening of the population for eye disease, enabling patients to gain early access to treatments that already exist.