[Clinical Edge] Can Drinking Coffee Before an Eye Pressure Test Raise Your Eye Pressure?

 "I had a cup of coffee before my eye exam. Will it affect my eye pressure test?"

As an ophthalmologist, I hear this question surprisingly often—especially from patients being evaluated for glaucoma.

The short answer is yes, caffeine may cause a temporary increase in intraocular pressure (IOP) in some people. However, drinking one cup of coffee does not automatically mean your test result is inaccurate or that you have glaucoma.

Can Caffeine Increase Eye Pressure?

Research suggests that caffeine can cause a small, temporary rise in intraocular pressure (IOP) in some individuals.

The effect varies from person to person and depends on several factors, including:

  • Your usual caffeine intake
  • Individual sensitivity to caffeine
  • Whether you have glaucoma or ocular hypertension
  • The amount of caffeine consumed

Many people experience little or no measurable change after drinking coffee.

Should You Reschedule Your Eye Pressure Test?

Usually, no.

If you've already had coffee before your appointment, there's generally no need to cancel or postpone your eye exam.

Your ophthalmologist can interpret your eye pressure measurement while taking your recent caffeine intake into account.

If your IOP is unexpectedly higher than usual, simply let your eye care provider know that you recently consumed coffee, tea, an energy drink, or another caffeinated beverage.

Does One High Eye Pressure Reading Mean You Have Glaucoma?

No.

A single elevated IOP reading is not enough to diagnose glaucoma.

Eye pressure naturally changes throughout the day and can also be influenced by:

  • Time of day
  • Corneal thickness
  • Stress or anxiety
  • Holding your breath or squeezing your eyelids
  • Measurement technique
  • Recent caffeine intake

Because of this, ophthalmologists diagnose glaucoma by looking at the whole picture—not just one number.

Additional tests may include:

  • Optic nerve examination
  • Optical coherence tomography (OCT)
  • Visual field testing
  • Repeat IOP measurements over time

What's the Best Way to Prepare for Future Eye Pressure Tests?

If you regularly have your eye pressure monitored, try to keep your testing conditions as consistent as possible.

For example:

  • Schedule your appointments at a similar time of day.
  • Avoid unusually large amounts of caffeine immediately before your visit.
  • Inform your doctor about any recent changes that could affect your results.

Consistency helps your ophthalmologist identify meaningful trends over time rather than focusing on a single measurement.

The Bottom Line

Drinking coffee before an eye pressure test may temporarily increase IOP in some people, but it does not invalidate your examination or mean you have glaucoma.

If your pressure is higher than expected, your ophthalmologist will consider your recent caffeine intake along with your medical history, optic nerve appearance, OCT findings, visual field results, and previous eye pressure measurements before making any diagnosis.

Disclaimer: This article is intended for general educational purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment.

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