Eccentric Viewing Techniques

In a large number of vision reducing conditions there is often some amount of residual vision available in the peripheral region of the eye or in patches within the overall visual field. Eccentric viewing is a technique that can be developed to encourage the use of these regions of vision and hopefully achieve a noticeable improvement in visual acuity.

Imagine the eye to have a reference line passing through the centre of its axis of rotation, by projecting this line back the point of intersection with the retina will be the macula. This can be considered to be the eye's principal visual axis. The brain will always strive to ensure that the principal visual axis is directed at any target for which clear, sharp and detailed image information is required. Any target off the principal visual axis will, by definition, fall onto the non-macula region of the retina where there is a lower concentration of the cells required for detail vision but a greater concentration of general awareness cells. This region of the retina is used for positional awareness and general mobility vision.

In conditions such as Age Related Macula Degeneration, there is a breakdown of the cells in the macula region of the retina with a subsequent loss of central sharp detail vision. Unfortunately, as stated on the previous page, the macula lies on the principal axis of the eye and so, whenever an object is viewed, the brain will align the axis so that the image will fall onto the poorly functioning macula. Eccentric viewing techniques encourage the sufferer to experiment with conscious control over which part of the visual field they will ‘see’ and how to use the off axis vision to view the desired object. To utilise the off axis vision the brain needs to be ‘fooled’ into directing the principal axis of the eye away from the object to be seen but in such a direction that the image of the target object falls onto a part of the retina that is still functioning.

An example would be the television screen. Under normal circumstances the principal axis would be directed at the screen. However, if a target object were to be placed on top of the television set (a clock for example), it would be possible for the sufferer to be directed to look at the clock but to concentrate on the image of the television screen below. The technique is quite difficult to master but once mastered there can be quite a significant improvement of visual acuity.

A related technique utilises the eye's ability to scan an object. By carrying out quick scanning actions a large area of the retina is exposed to the object and more information is available for the brain to interpret the image.

Eccentric viewing techniques and scanning techniques can be utilised to assist in reading as well as for distance viewing by following a similar method. Unfortunately there may not be quite such an improvement when compared to distance tasks due to the need for more detailed information when reading.

Both techniques require a considerable amount of practice and perseverance to master. However many of those suffering visual impairment stumble across the techniques unknowingly, as they come to terms with their reduced vision. Ultimately results are a factor of the individual’s adaptability and the incentives present to develop them. The most important additional factor is the support and encouragement of friends and family as well as the eye care team.