1. Principles and practices

This week I worked on defining my final project idea and started to getting used to the documentation process..

Introduction

My final project will be an ophthalmoscope which makes use of an infrared camera in order to focus and thus avoid the need for dilation

What is it?

An ophthalmoscope is a device used to examine and sometimes take pictures of the retina. Over of the course of various medical examinations, it is sometimes necessary to get an image of a patient’s retina in order to detect any possible damage or conditions. The retina is the back of a person’s eye, where the various light receptors are located. In order to take both video and images, a device like the one pictured above is used. It is important to note that this is a fairly standard and routine procedure conducted at any optician practice.

The design itself is rather simplistic; the head of the device mounts lenses, as well as a small light used to be illuminate the retina allowing the operator to see. The more basic models feature just a magnifying lens which allows the optician or ophthalmologist to conduct the examination. More advanced models, however, feature in built cameras which allow for taking pictures or video that can be analyzed at a later date. Furthermore these devices come in all shapes and sized, from the standard hand held device shown above to more complex desk mounted systems.

The issue when conducting this type of procedure is shinning enough light on the retina to be able to accurately examine it. Upon exposing the eye to light, the iris will immediately contract the pupil, which drastically reduces visibility. This means that whilst is it possible to conduct an examination on normal conditions, it is very hard to detect subtle symptoms or abnormalities; Instead, it serves to perform a rough and basic inspection.

When it is deemed necessary to perform a more in depth examinations, then special anaesthetic eye drops are used. These drops are applied to the eye, and serve to relax the pupil, stopping it from being able to contract altogether for a few hours. After applying the drops, it is possible to perform a far more in depth and reliable examination, since one can shine a light on the eye and not have it contract, allowing for much better visibility.

This method (which is currently the only method available) comes with a few drawbacks. First is the issue of practicality. The drops have to be applied in a hospital by specially trained professionals, meaning that an optician cannot perform this procedure at their practice. The optician has to refer the patient to their designated hospital where they then must make an appointment, which in some cases can be a period of over one month. Furthermore, the drops themselves are relatively painful, meaning that it is quite difficult to apply them to children, for example. Finally, the drops mean that the patient will be unable to adjust properly to changes in light for several hours, often for the rest of the day: They will be unable to drive, and in some cases, unable to even see well enough to use public transport (not to mention other basic tasks like cooking). As such, the individual will often require someone to aid them for the rest of the day. This, again, makes the procedure somewhat impractical.

Having identified this issue, my project aims to create an alternative. The first idea was to employ either a low light camera or an infra red/ultra violet device. The issue is that being able to see the eye in colour is important for the examinations, whereas the above methods all produce images in black and white. However, what any of the above methods would allow for is focusing a camera.

Thus, the patient can be brought to a dark room, wait until their pupil naturally dilates, and then use an infra red light to focus the camera on the retina. Once the camera is focused, it can then use a conventional flash to illuminate the retina, as by the time the iris starts to contract, the picture has already been taken.