Does coffee have an effect on your eyes?

The 2017 National Coffee Drinking Trends report showed that 62 percent of more than 3,000 people who participated in the online survey said they had drunk coffee the previous day, which is interpreted as daily consumption. This was up from 57 percent in 2016, said the report, which was released at the coffee association's conference in Austin, Texas.

Even though the U.S. population is drinking more coffee than ever it still only ranks 22nd overall in per capita consumption. The people of Finland average 3 times as much coffee consumption as in the U.S.

So what does all this caffeine intake do to our eyes?

The research is rather sparse and the results are mixed.

Here are the major eye topics that have been investigated:

Glaucoma

One study, published in the journal Investigative Ophthalmology and Visual Science, showed that coffee consumption of more than 3 cups per day compared to abstinence from coffee drinking led to an increased risk for a specific type of Glaucoma called Pseudoexfoliation Glaucoma.

Another analysis of several existing studies by Li,M et al demonstrated a tendency to have an increase in eye pressure with caffeine ingestion only for people who were already diagnosed with Glaucoma or Ocular Hypertension, but no effect on people without the disease. A separate study, published by Dove Press, done with the administration of eye drops containing caffeine to 5 volunteers with either Glaucoma or Ocular Hypertension showed that there was no change in the eye pressure with the drops administered 3 times a day over the course of a week.

Summing up the available studies in terms of Glaucoma, the evidence points to maybe a slight increase in Glaucoma risk for people who consume more than 3 cups of coffee a day.

Retinal Disease

A study done at Cornell University showed that an ingredient in coffee called chlorogenic acid (CLA), which is 8 times more concentrated in coffee than caffeine, is a strong antioxidant that may be helpful in warding off degenerative retinal disease like Age Related Macular Degeneration.

The study was done in mice and showed that their retinas did not show oxidative damage when treated with nitric oxide, which creates oxidative stress and free radicals, if they were pretreated with CLA.

Dry Eyes

A study published in the journal Ophthalmology looked at the effect caffeine intake had on the volume of tears on the surface of the eye. In the study, subjects were given capsules with either placebo or caffeine and then had their tear meniscus height measured. The results showed that there was increased tear meniscus height in the participants who were given the caffeine capsules compared to placebo. Increased tear production, which occurred with caffeine, may indicate that coffee consumption may have a beneficial effect on Dry Eye symptoms.

Eyelid Twitching

For years eye doctors have been taught that one of the primary triggers for a feeling of twitching in your eyelid has been too much caffeine ingestion (along with stress, lack of sleep and dry eyes). I have been unable to find anything substantial in the literature to support this teaching. Therefore, I’m going to have to leave this one as maybe, maybe not.

The End Result

Overall, the evidence for the pros and cons of coffee consumption and its effects on your eyes appear to be rather neutral. There are one or two issues that may increase your risk for glaucoma but it also may decrease your risk of Macular Degeneration or Dry Eyes.

Since there is no overwhelming positive or negative, our recommendation is, and this holds for most things, enjoy your coffee in moderation.

Related links

• Study: Coffee is good for your eyes
• Study links caffeinated coffee to vision loss
• Effect of caffeine on intraocular pressure
• Effect of caffeine in patients with primary open angle glaucoma
• Drinking coffee prevents eye damage
• Caffeine increases tear volume

Article contributed by Dr. Brian Wnorowski, M.D.

This blog provides general information and discussion about eye health and related subjects. The words and other content provided on this blog, and in any linked materials, are not intended and should not be construed as medical advice. If the reader or any other person has a medical concern, he or she should consult with an appropriately licensed physician. The content of this blog cannot be reproduced or duplicated without the express written consent of Eye IQ.

There are several different variations of Glaucoma, but in this article we will mainly focus on Primary Open Angle Glaucoma. This means that there is no specific underlying cause for the Glaucoma like inflammation, trauma or a severe cataract. It also means that the drainage angle where fluid is drained from the inside of the eye into the bloodstream is not narrow or closed.

Closed or Narrow Angle Glaucoma, which will be discussed in another article, is treated differently from Open Angle Glaucoma

In the U.S., Primary Open Angle Glaucoma (POAG) is by far the most common type of Glaucoma we treat.

Glaucoma is a disease where the Optic Nerve in the back of the eye deteriorates over time, and that deterioration has a relationship to the Intraocular Pressure (IOP).  Most - but not all - people diagnosed with Glaucoma have an elevated IOP.  Some people have fairly normal IOP’s but show the characteristic deterioration in the Optic Nerve. Regardless of whether or not the pressure was high initially, our primary treatment is to lower the IOP. We usually are looking to try to get the IOP down by about 25% from the pre-treatment levels.

The two mainstays of initial treatment for POAG in the U.S. are medications or laser treatments. There are other places in the world where Glaucoma is initially treated with surgery. However, while surgery can often lower the pressure to a greater degree than either medications or laser treatments, it comes with a higher rate of complications. Most U.S. eye doctors elect to go with the more conservative approach and utilize either medications - most often in the form of eye drops - or a laser treatment.

Drops

There are several different classes of medications used to treat Glaucoma.

The most common class used are the Prostaglandin Analogues or PGA’s.  The PGA’s available in the U.S. are Xalatan (latanaprost), Travatan (travapost), Lumigan (bimatoprost) and Zioptan (tafluprost).

PGA’s are most doctors’ first line of treatment because they generally lower the IOP better than the other classes; they are reasonably well tolerated by most people; and they are dosed just once a day, while most of the other drugs available have to be used multiple times a day.

The other classes of drugs include beta-blockers that are used once or twice a day; carbonic anhydrase inhibitors (CAI’s ), which come in either a drop or pill form and are used either twice or three times a day; alpha agonists that are used either twice or three times a day; and miotics, which are used three or four times a day. All of these other medications are typically used as either second-line or adjunctive treatment when the PGA’s are not successful in keeping the pressure down as single agents.

There are also several combination drops available in the U.S. that combine two of the second-line agents (Cosopt, Combigan, and Symbrinza).

Laser

The second option as initial treatment is a laser procedure.

The two most common laser treatments for Open Angle Glaucoma are Argon Laser Trabeculoplasty (ALT) or Selective Laser Trabeculoplasty (SLT).  These treatments try and get an area inside the eye called the Trabecular Meshwork - where fluid is drained from the inside of the eye into the venous system - to drain more efficiently.

These treatments tend to lower the pressure to about the same degree as the PGA’s do with over 80% of patients achieving a significant decrease in their eye pressure that lasts at least a year.  Both laser treatments can be repeated if the pressure begins to rise again in the future but the SLT works slightly better as a repeat procedure compared to the ALT.

Article contributed by Dr. Brian Wnorowski, M.D.