It’s not uncommon for people to notice that one of their eyes sees colors differently than the other. Often, one eye may take on a greener hue while the other sees colors normally. But what causes this curiosity of vision? There are a few possible explanations that eye doctors have uncovered over the years.
Anisocoria – Uneven Pupil Size
One potential cause is a condition called anisocoria, which is when the pupils are uneven in size. It’s normal for pupils to frequently differ in size, even if minimally. However, more pronounced unevenness can affect color perception.
The pupil is the black circular opening located in the center of the iris. It regulates the amount of light entering the eye by dilating (getting larger) in dim lighting and constricting (getting smaller) in brighter environments.
If one pupil is significantly larger than the other, it will allow more light into that eye. This can create a color imbalance, causing one eye to take on a greenish tint while the other sees colors normally. The larger pupil overwhelms the eye with light waves, skewing color perception.
Astigmatism
Astigmatism is another common vision condition that can cause one eye to see more green than the other. With astigmatism, the cornea has an irregular, football-shaped curvature rather than a properly spherical one.
This results in blurred vision from an inability to properly focus light. Objects often appear stretched out or distorted. The degree of visual impairment depends on the type and severity of the astigmatism.
Like anisocoria, astigmatism can lead to an imbalance of light entering the eyes. The eye with the more severe astigmatism will receive excess light, taking on a subtle green/yellow discoloration. The other eye will see colors normally.
Corneal Injury or Disease
If one eye has suffered corneal damage from injury or disease, color perception can shift toward the green end of the spectrum in that eye.
The cornea is the transparent outer layer of the eye which refracts light along with the lens. When its regular curvature is disrupted, light scatters abnormally. As a result, shorter light wavelengths like blue get filtered out more easily, making the world appear more yellow-green.
Examples of corneal conditions that can cause green-tinted vision include:
- Keratoconus – The cornea thins and takes on a cone-like shape
- Fuchs’ dystrophy – Corneal cells gradually die off
- Corneal scarring – Scar tissue forms on the cornea
Physical trauma like an abrasion or scratch can also damage the cornea enough to create a green shift.
Cataracts
A cataract involves the lens inside the eye becoming progressively opaque. Normally, the lens should be crystal clear to accurately refract light to the retina. As cataracts advance, the lens takes on a yellow/brown discoloration that filters out bluish light waves.
When cataracts affect one eye more than the other, which is common, the worse eye will start to perceive colors with a greenish tint. The other healthy eye will see colors normally. Over time, as the cataract worsens, the greenish cast will become more pronounced.
Differences in Macular Pigment
The macula is the small central area of the retina responsible for sharp, straight-ahead vision. It contains high concentrations of specialized carotenoid pigments that filter out damaging blue light frequencies. These pigments lend the macula its yellowish color.
There can be subtle differences in macular pigment density between the two eyes. The eye with denser macular pigments will take on a more yellowed view of the world and process colors differently. The other eye will see colors more neutrally without the excess filtering of blue light wavelengths.
Examining Color Vision Differences
During an eye exam, there are specialized tests your eye doctor can perform to assess potential color vision deficits:
Ishihara Color Plate Test: This test displays colored dots arranged in different numerals and patterns. It allows quick detection of color blindness issues.
Farnsworth D-15 Test: Here, you arrange a set of 15 colored caps in consecutive color order. Deviations from the proper sequence reveal color vision errors.
Anomaloscope Test: This device lets you mix red and green light beams. You compare your adjusted mix to a standard color sample. An inability to reliably match the color points to a color perception problem.
Contrast Sensitivity Testing: Charts with decreasing levels of contrast and color differences can identify subtle color discrimination loss.
These tests help determine if there is an underlying medical condition causing the color variance between your eyes, like a corneal condition or cataract. They also reveal if the issue stems from innate differences in eye anatomy and retinal pigmentation.
Treatment Options
The course of treatment will depend on the specific reason behind one eye seeing greener hues. Here are some potential treatment options:
Corrective Lenses: Glasses or contacts can compensate for focusing issues from corneal irregularities and astigmatism to provide clearer, more balanced vision.
Pupil-Size Equalizing Drops: These medicated eye drops constrict an enlarged pupil down to an equal size as the other eye, eliminating excess light exposure.
Surgery: For severe astigmatism and keratoconus, corneal procedures like LASIK can reshape the cornea. Cataract surgery also replaces the cloudy lens.
Dark Tint Contact Lens: This specially designed lens blocks excess light from entering the eye with the larger pupil. It neutralizes the color imbalance.
If the cause is untreatable innately different retinal pigmentation, compensatory treatments like light-balancing tinted contacts can offset the greenish cast.
When To See An Eye Doctor
You should consult an eye care professional if you notice one eye consistently sees the world with a greenish tint. They can examine your eyes and perform diagnostics tests to pinpoint the exact reason.
See an optometrist or ophthalmologist promptly if the green-colored vision is:
- Accompanied by other symptoms like eye pain, tearing, light sensitivity, halos, or headaches
- Interfering with your daily functioning and quality of life
- Worsening over time
Sudden onset of green-tinted vision also warrants urgent evaluation to rule out a detached retina or stroke. Catching any eye condition early maximizes treatment potential before permanent vision loss sets in.
Coping Tips for Green-Tinted Vision
If one eye has an incurable tendency to see greener, there are some coping methods you can try:
- Use daylight or full-spectrum light bulbs to balance color perception
- Try an independent dark tint contact lens to filter excess light
- Sit closer to the television and avoid glare on screens
- View fine details and reading material first with the unaffected eye
- Turn down brightness settings on devices and reduce blue light exposure
- Avoid situations where accurate color judgment is vital, like painting or clothing shopping
With time, the brain can adapt and compensate for the skewed color input from one eye. Also, be sure to protect both eyes from UV and high-energy visible light, which can worsen color perception issues.
In Summary
If you notice one of your eyes routinely seeing the world through a green filter, several different eye conditions could be the cause. Have a comprehensive eye exam to diagnose the reason. Treatment options like corrective lenses, ocular injections, or surgery can help neutralize the color imbalance in many cases. But if the cause is innate retinal differences, compensatory techniques and tinted lenses can help you adapt. With the right eyecare, you can gain better control over the frustrating discoloration.
Frequently Asked Questions
Why would only one eye see more greenish?
Potential causes include unequal pupil size, astigmatism, corneal damage, cataracts, differences in macular pigment density between the eyes, and innate structural variances. One eye takes on a green tint due to excess light exposure, light scattering, or filtering of blue wavelengths.
Is this condition serious?
Seeing a greenish tint through one eye can indicate an underlying problem, but it is seldom serious on its own. Still, have an eye doctor examine it, especially if sudden or accompanied by other symptoms. Catching conditions early allows more treatment options.
How do you fix it?
The right solution depends on the cause. Possibilities include corrective lenses, pupil dilating drops, corneal surgery, cataract removal, light filtering lenses, or compensatory techniques if it is untreatable. An eye doctor will advise the best management approach.
Can both eyes eventually see green?
If the cause stems from an eye condition like advancing cataracts, corneal dystrophy, or untreated glaucoma, it is possible for the greenish discoloration to gradually affect both eyes over time. Regular eye exams help monitor this.
When should you see a doctor?
Consult an eye doctor promptly if the green tint occurs suddenly, causes other symptoms, increasingly impairs vision, or spreads to the other eye too. Also if it negatively impacts your functioning. Routinely get your eyes checked so any issues are caught early.
Conclusion
A difference in color perception between the two eyes is fairly common but deserves professional evaluation. Seeing green out of one eye is no cause for alarm, but diagnosing the origin allows appropriate care to preserve vision function. With regular eye exams and timely treatment as needed, the outlook for managing this frustrating chromatic quirk is quite good.
