People may agree or disagree and have different opinions, but going to local trials and picking up few dogs that have jumping issues and doing eye testing is not a science experiment in my book. There are too many variables exist that will need to be removed for even small case study to create valid conclusions- structure, breed, flooring, footing, training, venues dog competes, age, eye set, handling beliefs to name a few.
Not only that but we can not come from same stand point in viewing dog´s vision as human´s. Dogs simply do not use it same way humans do. Example- I can put a hide/odor/ in very clear obvious area and dog still will be searching using his nose.
Additionally undiagnosable vision issues might not be related to vision at all
http://jn.physiology.org/content/41/4/896.abstract
What if the puppy vision was not stimulated during critical period of development? Because that period is short and by the time handler picks up 8 weeks old puppy all brain functions are formed. Something akin to those cases when in the past human babies were raised by animals, if they were returned to humans past 6 year old they were never able to learn human speech.
I am not saying that ETS does not exist, what I am saying that going around labeling dogs as having ETS based on jumping problems, not finding current eye problems and not being able to fix it with jump retraining is not science in my book.
here is another article, food for the thought
http://speedoggie.blogspot.com/2011/10/another-way-of-looking-at-early-take.html
BTW, the article author is hugely talented visual artist who spend years building art on tricks of visual perception
http://www.devorahsperber.com/installation_views.htm