New Study Links Caffeinated Coffee To Vision Loss

dsinc writes "A new study suggests caffeinated coffee drinkers should limit their intake to reduce their chances of developing vision loss or blindness. According to a scientific paper in Investigative Ophthalmology & Visual Science, heavy caffeinated coffee consumption is associated with an increased risk of developing exfoliation glaucoma (abstract), the leading cause of secondary glaucoma worldwide. 'Scandinavian populations have the highest frequencies of exfoliation syndrome and glaucoma,' said author Jae Hee Kang, ScD, of Channing Division of Network Medicine at Brigham and Women's Hospital in Boston, Mass. 'Because Scandinavian populations also have the highest consumption of caffeinated coffee in the world, and our research group has previously found that greater caffeinated coffee intake was associated with increased risk of primary open-angle glaucoma, we conducted this study to evaluate whether the risk of exfoliation glaucoma or glaucoma suspect may be different by coffee consumption.'"

Comments

Statistically Meaningless Conclusions

[Geoffrey.landis]

Sorry, their conclusions are just not statistically justified.

Let me review what they found:
Compared total caffeine consumption of less than 125 mg/day to greater than 500 mg/day: no significant result
Compared abstain from caffeinated coffee to greater than 3 cups of caffeinated coffee daily: glaucoma relative risk in the interval 1.09 to 2.54
Compared consumption of (caffeinated soda, caffeinated tea, decaffeinated coffee or chocolate) to non-consumers of same: no significant result

That relative risk that they quote as being significant has a confidence interval with a lower end of 1.09; which is only barely above 1.0 (1.0= no effect). So, they studied one particular variety of one particular minor disease (of many health effects). Finding one effect at a trivial level is meaningless.

Ob xkcd: http://xkcd.com/882/