Prescription to aid reading attention

Dr Jennings (Letters, June 9) quoted several effects that a yoked prism (prism base down or up in both eyes) prescription could have upon visual performance. Of those listed I would propose 'expanded peripheral awareness' as the most likely cause for improvement in reading. All visual tasks involve attention to detail and attention to surroundings. This is crucial to success not only in movement tasks but also with communication, with reading, and with memory. Imagine reading without good use of side vision. How would we keep place, what errors would we make, what would happen to our speed of reading and how would our voice sound when reading aloud? Our attention to detail and the surroundings is not static. The more attention we attach to para-central, the less we can apply to centre. This attention is a dynamic process. Some of our patients have trouble moving their attention in this way. Treating this problem can make a huge difference to learning and study. Apparently, one of the most potent tools we have for changing the balance between centre and surround is low power lenses. All the optometrist needs is time (usually five to 10 minutes), consideration of the best targets, a methodical approach and knowledge of the best questions to ask. Observation skills will do the rest. You will then hear and see the big difference a +0.75D, 1.5 prisms up or down, and 0.5 base-in prisms etc, can make for some patients. Efficient use of para-central vision is a strong theme of behavioural optometry. In behavioural optometry we consider what changes in visual performance (behaviour) would be helpful for the patient and measure performance before, during and after treatment. For more information, contact Lesley Arkin (tel 01908 567672 arkin@eyecare-mk.co.uk). Owen Leigh Alton, Hants