Bottomline: This is the first study to show that a high dietary omega-6 fat to omega-3 fat ratio is associated with a higher risk of developing Dry Eye Syndrome (DES),  one of the most prevalent eye problems that leads to vision difficulties while reading, using a computer and driving at night. 
                                                                                                          Am J Clin Nutr. 2005 Oct;82(4):887-93.

Summary: Researchers evaluated the diets of nearly 30,000 women, and found that a diet high in omega-3 fats decreased the risk of developing DES, which affects more than 10 million Americans.  Notably, eating about three-ounce of tuna, once per week was found to be particularly protective.  Conversely, a high dietary omega-6 fat to omega-3 fat ratio greater than 15:1 was associated with a more than twofold greater prevalence of DES than was seen with a low ratio.

A body of research has shown that  dietary intake of omega–3 fats and the ratio of their consumption to that of omega–6 fats affects the overall inflammation status in the body.  Notably, patients with DES have an increased concentration of inflammation compounds in the tear fluid (including cytokines, such as interleukin 1, interleukin 6, and tumor necrosis factor .)

Researcher's Conclusion:"Given the biology and importance of these FAs and their opposing biological effects, it seems quite likely that such an imbalance would be related to a pathologic condition"

Comment: This group of women had a lower omega-6 fat ratio than the typical western diet (90% had a ratio below current USA recommendations).  Therefore the researchers speculate that it's possible that imbalances of the dietary omega-6 fat to omega-3 fat ratio might have an even more profound impact on DES patients.

Link to FREE Full Text
Miljanović B et al. Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women.Am J Clin Nutr. 2005 Oct;82(4):887-93.