Look at the details - they are talking "associations."  The underlying
mechanism for catardacts is free radical damage, and that has been
known for a long time now.  Omega 3s and 6s are very susceptible to
free radical degradation, and Eskimos on "traditional diets" (high in
omega 3s) do have eye problems related to free radical damage, so these
people are no aware of the literature that is directly related to their
studies.  And those on high saturated fatty acid diets (as overall
percentage of calorie intake) have very little incidence, because these
fatty acids are quite resistant to free radical degradation.  Overall,
health and longevity is enhanced when you avoid free radical damage in
the body, and omega 3 and 6 PUFAs are the main causes of such damage in
Western nations.  Fish oil is really bad news, but it does counteract
the inflammatory, vasoconstrictive qualites of the omega 6s, and so
there are "health benefits" claimed, when in fact the evidence suggests
that one simply avoid these fatty acids in the diet (except for the
unavoidable trace amounts found in most food containing fat).

Eskimo (Inuit) are also exposed to vastly brighter light
levels than those surrounded by vegetation.