It is summer in State College. Barbecues, holidays like July 4th and local events like the Central Pennsylvania Festival of the Arts lead us to consume alcoholic beverages for their undeniable social and psychological effects. Alcohol has had its uses in ocular medicine over the years. We purposefully use alcohol to dissolve the corneal tissue before we wipe it away before certain surgeries. In the early 1900s, French and German physicians were also using alcohol to directly inject behind the eye to kill the nerves for people who were unlucky enough to have blind and painful eyes that were causing them agony.
But how often do we think about the effect that alcohol has on our eyes and vision? People with dry eye issues might want to think about alcohol a little bit differently.
The main active ingredient in alcoholic beverages is ethanol molecule. When ethanol is ingested into our bodies, it gleefully permeates the tissues in our body because of its small size and chemical properties that interact with the molecules in our cells. This means that alcohol diffuses to our eyes and their support structures. An important support structure of the eye are your tears, which are great for showing emotion and vital for maintaining the health and comfort of your everyday vision.
The tears on your eye are not simply excess water from the body that magically appear onto the front of the eye. In fact, it is a fascinatingly complex world which we call the tear film. It starts on the surface of the eye with small little corneal cells and their tiny fingerlike structures that desperately cling to a spaghetti-like mess of proteins called mucin. Next, we have the aqueous part of the tears which is the most plentiful part of the tears. The aqueous is a soup-like mixture made mainly of water, electrolytes and proteins including some small ninja-like proteins that can kill bacteria. Finally, the outer surface of the tears is what we call the lipid layer. The lipid layer has the difficult task of trying to keep the whole unruly mess from evaporating into the great big world in which we live.
When ethanol makes its way from the blood stream and diffuses into the tears, it disrupts the entire tear film. This disruption causes the layers of the tear film to break apart and your tears to evaporate off your eye and into the world. Ethanol also descends upon the corneal cells and indiscriminately murders them. When the tear film is disrupted and surface cells damaged, this promotes inflammation on the front surface of the eye and the festive evening leads to potentially red, scratchy, burning, uncomfortable eyes. How do we know drinking alcohol has these negative effects on the harmony of the tear film? Some of my favorite research on the subject comes out of South Korea, where they decided to get a few of their college students drunk to study the tear film. Perhaps we should converge downtown when the fall semester gets back into full swing to gather some more data?
At the next event with alcohol involved, be aware that your beverage might have more of an influence on your eyes than you might think!