Optometric imaging systemsPart 3: Retinal imaging systems

This is the final part of a series on optometric imaging systems. Part 1 concentrated on camera technology, discussing the image transfer, storage, lighting and optical considerations involved with imaging. Part 2 examined the area of anterior eye imaging and, in a similar manner, this article investigates current retinal imaging equipment available in the UK, highlighting the wide variety of systems available and comparing their relative strengths and weaknesses. Retinal cameras have been available for many years as explained in Part 1 of this series. Traditional film based systems had additional 'consumable' costs Ð for example, the film and its processing. There was also the significant delay between capturing an image and being able to view it. This resulted in variable image quality and reduced efficiency in clinical care. Most retinal cameras now use digital imaging, allowing for images to be taken and instantaneously viewed. This offers the benefits of immediate determination of the most appropriate luminance to be used and enables the viewer to maximise image positioning and clarity before capture. It is interesting to note that although the Glasgow workshop of the National Screening Committee recommended the use of digital photography as better for diabetic screening than film, polaroid and dilated ophthalmoscopy,1-4 not all studies have shown similar results.5,6 Up-to-date information on the diabetic screening issue can be found at www.nscretinopathy.org.uk and www. doh.gov.uk/research/index.htm.