I was pleasantly surprised to read Bill Harvey’s column in Optician. He explains that he has always been concerned that we (optometrists) tend to focus too much on Snellen acuity as a gauge of vision quality when much of what we see, indeed perhaps most, is down to higher processing by the brain.
This is exactly what behavioural optometrists have been explaining for at least 50 years.
Sight cannot be regarded on its own. In order to read one needs to see the letters, but also to maintain exact focus without tiring, to point both eyes exactly to the letter being viewed and then follow along the line of print accurately. To do this the cortex has to send signals to all 12 extra ocular muscles plus the focusing muscles – quite a complex task.
But this is not all one needs to read. One needs to understand what one has read from past experience and connections between the visual cortex and other parts of the brain. Such as gross motor, auditory, speech and language.
Recent research using MRI scans has shown that the visual cortex is connected to some 80% of the brain. Vision leads gross motor movements and optometrists that practice ‘sports vision’ are using behavioural optometry vision therapy exercises to enhance top sports men and women to improve their game. Vision leads writing and spelling. You cannot write if you have not seen and developed a picture in your visual cortex of what letter or word to write. Thus it is connections from the visual cortex to the fine motor muscles of the fingers that direct writing.
As optometry wakes up to the fact that 6/6 VA is not the be all and end all, perhaps they will realise behavioural optometry and vision therapy can enhance our visual system.
Lesley.shimon@btinternet.com