Hello and thanks for researching this important question!
Labradors do carry a genetic kind of cataract that does become apparent in youngsters.
http://www.labradornet.com/geneticdefects.html
http://www.labradorforums.co.uk/eyes.html
http://www.doghealth.mypetdogs.com/labrador_dog_health.htm
Many of these congenital cataract conditions do not interfere with daily vision, but dogs that participate in any field trials should be evaluated by a licensed Veterinary Ophthalmologist when vision is in question.
This pup should be examined even if this is some kind of vaccine reaction, because your son needs to know if this pairing is producing weak offspring. At the very least, he should consider using a different vaccine if no defect is found!
Here is a link you can use to find a nearby eye specialist:
http://www.acvo.org/locate.htm
Edited by GenB on July 11 2006 at 4:17 PM
Your concern has touched me--if you have follow-up questions, or need to clarify your case, please let me know right away! Your "Accept" helps me reach out to others!