[Clinical Edge] Can Artificial Tears Affect Your OCT Scan Results?

If you used artificial tears just before your OCT scan, there's usually no need to worry.

A drop or two of artificial tears is unlikely to change the actual structure of your retina or optic nerve. However, artificial tears can affect the quality of the scan by changing the condition of the tear film on the surface of the eye.

This is why it's helpful to let your eye care provider know what eye drops you used before the examination.

Can Artificial Tears Change Retinal Thickness?

No.

Artificial tears are designed to lubricate the surface of the eye. They do not change the thickness of the retina, the macula, or the retinal nerve fiber layer within a few minutes.

If your OCT shows a change in retinal thickness, it is almost certainly not because you used artificial tears immediately before the scan.

Why Can Artificial Tears Affect an OCT Image?

Optical Coherence Tomography (OCT) uses light to create highly detailed cross-sectional images of the retina and optic nerve.

Before the light reaches these deeper structures, it must first pass through the:

• Tear film
• Cornea
• Lens
• Vitreous

If the tear film is unstable because of dry eye, the OCT signal may become weaker or the image less clear.

Ironically, using artificial tears before the scan may actually improve image quality in patients with dry eye by creating a smoother optical surface.

In other words, artificial tears influence how clearly the eye is imaged, not the anatomy being measured.

Should the OCT Scan Be Repeated?

Usually not.

Simply using artificial tears before an OCT scan is not a reason to repeat the test.

Instead, the decision depends on the quality of the images.

If the scan has:

• Good signal strength
• Clear retinal layer definition
• Minimal artifacts
• Reliable measurements

the results are generally considered valid.

If the images are blurry, have poor signal strength, or cannot be interpreted confidently, your eye care professional may repeat the scan.

The quality of the image is much more important than whether artificial tears were used.

What If You Already Used Artificial Tears?

There's no reason to hide it or feel concerned.

Simply tell the technician or ophthalmologist:

• Which eye drops you used
• Approximately when you used them
• Whether they were preservative-free artificial tears or another medication

This information helps interpret the scan if image quality is less than ideal.

What About Other Eye Drops?

Artificial tears are very different from prescription eye medications.

If you recently used:

• Dilating drops
• Glaucoma eye drops
• Steroid eye drops
• Antibiotic eye drops
• Eye ointments

you should also mention them before your examination.

Some medications can influence pupil size, ocular surface quality, or intraocular pressure, which may affect certain eye examinations or their interpretation.

Tips Before an OCT Examination

To obtain the best possible images:

• Blink normally before the scan.
• Tell the technician if you have dry eyes.
• Mention any eye drops you used that day.
• Keep your eyes as still as possible during the scan.
• Follow the technician's fixation instructions carefully.

These simple steps often improve image quality more than avoiding artificial tears.

Key Takeaway

Using one or two drops of artificial tears immediately before an OCT scan does not change the structure of the retina or optic nerve.

However, artificial tears can affect the tear film and, in many cases, actually improve image quality—especially in people with dry eye. The reliability of an OCT examination depends primarily on the quality of the captured images, not simply on whether artificial tears were used beforehand.

Disclaimer: This article is for educational purposes only and is not a substitute for personalized medical advice, diagnosis, or treatment.