For low vision specialists and those who consult them
Visual impairment and traumatic brain injury
July 17, 2009Posted by on
In my last post I mentioned that traumatic brain injury (TBI) is an increasingly important cause of visual impairment in the USA, in particular in returning servicemen. As it happens, a paper in the July Optometry & Vision Science by Brahm and colleagues discusses this issue in depth.
It is important to realise that although military personnel from the Iraq and Afghanistan conflicts are the most publicised group of people with TBI, in the USA 650,000 cases of TBI are caused every year by road crashes and falls.
Brahm and colleagues examined data from 68 inpatients with moderate-severe TBI and 124 outpatients with mild TBI. All were veterans.
Of those with severe TBI (inpatients), 22% had vision of worse than 20/70 (6/21), with 3% of the sample having no perception of light.visual impairment of but had at least light perception; of 20/100 (3/60) to PL; and 6% had visual acuity between 20/100 (3/60) and 20/70).
About one-third of the inpatients and 3% of outpatients had visual field loss with most of these being hemianopia defects.
A very large proportion of the population reported reading difficulties (87% of outpatients; 66% of inpatients) which may be caused by other ocular and oculomotor problems identified in this study, including convergence insufficiency, accommodative insufficiency, strabismus and saccadic dysfunction.
The paper has really emphasised to me that TBI is a very varied diagnosis which probably encompasses many different conditions. I was particularly interested to learn about the large number of civilians who may also have this condition. Encouragingly, a relatively high proportion of the TBI population would appear to have visual problems which could be helped with low vision rehabilitation, and I imagine that this is an area we will hear more about in the coming years.