The effect of coffee consumption on eye health   

With the emergence of new studies, the effect of drinking coffee on eye health is becoming more debatable. Consuming a large amount of coffee has been associated with a reduction in tear film quantity causing dryness. In the long run, the minor discomfort sensation can develop into chronic dry eyes and will be allied to light sensitivity, blurriness, and possible infections. Dryness might be more acute for contact lens wearers and smokers. On the other hand, other researchers consider that the grittiness caused will stimulate the glands to produce more tears. And even a group of researchers found that the prevalence of dry eye decreased as coffee consumption increased.  

A study on the effects of consumption of coffee on Open-angle Glaucoma suggested that coffee consumption may increase the risk of Open-angle Glaucoma in particular among men. The study compared a group of coffee drinkers with a control group of non-drinkers. A 2014 Cornell study suggests that a cup of coffee per day may be beneficial for your eye health. It helps prevent blindness from retinal degeneration related to glaucoma, aging, and diabetes. It appeared that coffee protects the retina thanks to the antioxidant Chlorogenic acid present in raw coffee.

With the absence of a knockout answer that assumes if coffee is either good or bad for eye health, everything is good as long as it is consumed in moderation.