There are several causes of visual deficiencies; they could be congenital (optic nerve hypoplasia or atrophia), post-trauma, degenerative (macular degeneration) or secondary to other pathologies (glaucoma, diabetes, etc).
The number of babies suffering from visual impairment is on the rise, primarily due to the improved survival rate among very low birth weight premature babies. In fact, 23% of them are severely visually impaired. The development of children with visual impairment is delayed and their progress through normal developmental stages is heavily compromised.
Vision impairment is also on the rise, largely due to the aging population and the cost associated to it is accordingly increasing. Statistics Canada, in its report entitled “A profile Of Disability in Canada 2001” showed that around 611,000 Canadians identified themselves as having seriously impaired vision. According to their projection, this number will increase to 700,000 by 2010 and in 2020, more than 828 000 cases will be reported. In the United States of America, the annual direct cost of visual deficiency, in 1981 was 14 billion USD, in 1995, it was evaluated to 38 billions and it is constantly on the rise.
Presently, there is no cure for these pathologies. The identification of the mediators implicated in visual axon guidance and synaptogenesis is a valuable venue for developing new therapeutic agents to treat these incurable diseases.