Why might someone need a fluorescein eye stain test?
What is an eye stain test used for?
If you’ve ever experienced pain on the surface of your eye, you’re probably familiar with a level of discomfort that can range from slightly irritating to completely debilitating.
A stinging, burning or scratching sensation could point to an injury on your cornea, the outer layer of the eye. This could also mean a tiny object or objects are lodged in or around your eye.
In either case, your eye doctor may choose to perform an eye stain test. Using a dye called fluorescein, this test is an easy way to check the outside of your eye for abnormalities.
What is an eye stain test?
An eye stain test specifically involves the cornea, the outer layer of the eye. The test is simple in nature and typically only takes a minute or two.
An eye doctor uses a dropper and a small strip of paper to place orange fluorescein dye on the surface of a patient’s eye. The eye doctor will then have the patient blink quickly to spread the dye along the cornea.
The process is usually painless, but could involve a slight stinging or scratching feeling.
Once the dye is evenly distributed across the surface of the eye, the doctor will shine a blue light on your cornea. When the blue light combines with the orange dye, any abrasions or debris along the cornea will show with a greenish tint.
Depending on what he or she sees, your eye doctor will then determine if treatment is needed. After the test, the dye’s slight orange color will go away on its own.
What can an eye stain test detect?
Abrasions and injury
Injury to the cornea can be caused by objects we use all the time. Accidental fingernail scratches are one of the most common culprits behind eye abrasions.
Since the cornea is relatively fragile, it doesn’t take much force for a misplaced scratch to leave a painful abrasion on the surface. Rubbing your eyes too harshly or frequently, along with other causes like severe dry eye, can also result in abrasions.
A stain test can detect more serious injury to the cornea too, in which case your doctor may suggest more intensive treatment.
SEE RELATED: Corneal abrasion: How to treat a scratched eye
Contact lens irritation
Newly prescribed contacts can sometimes irritate your cornea and cause discomfort.
Your eye doctor may use a fluorescein stain test to determine the amount of irritation and whether you should discontinue using that specific type of contact lens. The eye stain test’s results can help your eye doctor to find different lenses that don’t aggravate your eyes.
Debris in the eye
Eyelashes, dust particles and even grains of sand can get trapped on your eye and irritate the cornea. When the sensitive surface of your eye is disrupted, it can make opening or moving your eye feel uncomfortable or painful.
A doctor may be able to remove the object in the office or may suggest additional treatment.
Infection or other disorders
The results of an eye stain test can point to a corneal infection, whether caused by a scratch, foreign body or a related eye condition. An ophthalmologist can help you determine if further testing or treatment is needed.
Can fluorescein dye permanently stain your eye?
No, although it will stain contact lenses that haven’t been removed. For this reason, your doctor will ask you to remove your contact lenses before an eye stain test.
What’s the difference between a fluorescein stain test and fluorescein angiography?
Simply put, the stain test is external and the angiography is internal.
While a stain test involves placing dye on the outside of the eye, a fluorescein angiography involves injecting a similar dye directly into the bloodstream.
In this test, an ophthalmologist dilates the pupils with eye drops and injects a small amount of dye into a vein in the patient’s arm. Your eye doctor will then take pictures, called fluorescein angiograms, using a special tool.
Your eye doctor then uses a light to look into the patient’s eyes, noting any abnormalities along the retina — the layer of tissue that lines the back of the eye.
A fluorescein angiography test can be used to detect retinal issues due to injury or diseases like diabetes, hypertension and other underlying causes.
Do I need an eye stain test or angiography?
Both an eye stain test and fluorescein angiography test can be valuable tools in diagnosing and treating certain eye-related issues, but only an optometrist or ophthalmologist can help you decide which tests might be beneficial.
Once your eyes have been examined, your eye doctor will work with you to assess any physical signs and symptoms, and help you determine if additional screening or treatment is necessary.
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Page updated January 2021