Blurry Vision with Soft Contact Lenses: A Guide for High Myopia

Q: Blurry Vision with Soft Contact Lenses: A Guide for High Myopia

Hello： Based on the situation you described, there are several possible reasons that could explain your vision fluctuations：<br>1. <br>Inconsistent prescription between glasses and contact lenses： You mentioned that the prescriptions for your glasses and contact lenses differ, wh

One eye is blurry with soft contact lenses?

Hello Doctor: I have high myopia (the most recent measurement was two weeks ago: left eye approximately -1200 diopters with astigmatism of -175; right eye approximately -1075 diopters with astigmatism of -175).
However, each time I have my eyes measured, the diopter and astigmatism values vary; sometimes the astigmatism is -150 and other times -200.
The diopter can also vary by nearly 100 diopters (left eye -1125, right eye -1025).
The optical shop said this is normal, and that measurements can fluctuate between 75 to 100 diopters at different times.
My current glasses prescription (newly fitted two months ago) is: left eye -1050, astigmatism -125; right eye -1000, astigmatism -125.
With this prescription, my right eye vision is 20/20, while my left eye is 20/25 (the left eye prescription is not as strong as the right eye, so when I cover one eye, I can clearly feel that my left eye vision is not as sharp, as I have mentioned to the optometrist that a stronger prescription for the left eye would be uncomfortable).
I occasionally wear rigid gas permeable contact lenses, with a prescription of left eye -1075 and right eye -1050 (fitted four years ago, but I still find them very clear).
Around the end of April, I tried soft contact lenses with a prescription of left eye -1000 and right eye -950; at that time, I felt that my left eye could see clearly both near and far, but my right eye was clear for near vision but not as clear for distance compared to the left eye, although the clarity of both eyes was not significantly different.
I wondered if there was an issue with my eyes, so I consulted a doctor and had my vision checked, and they said everything was normal.
I can see clearly both near and far with my glasses (I have slightly elevated intraocular pressure, and the doctor suspects glaucoma, with optic nerve degeneration at around 80%, but my visual field test is normal, so I am under regular follow-up).

Yesterday, I had an event to attend, so I intentionally wore soft contact lenses with both eyes at -950 diopters.
Logically, my left eye should be less clear than my right eye, but I found that my left eye could see clearly both near and far; however, my right eye became very blurry for near vision (like small text in books or on my phone), and I could only see distant objects clearly, and even then, they were clearer than with my left eye.
After removing the soft contact lenses and putting my glasses back on, my vision returned to normal clarity.
The current soft contact lens prescription was provided by the optical shop, which suggested that for near vision, I should have right eye -900 and left eye -950; for distance vision, right eye -950 and left eye -1000 (the contact lens type is Menicon Z silicone hydrogel high oxygen permeability).
My right eye becomes blurry as soon as I put the lens on, while I have mild dry eye issues, but there is no blurriness problem with my left eye.
I have been wearing soft contact lenses for five years, previously with both eyes at -950 diopters, using the same type.
The right eye has a lighter prescription, so my past experience has always been that my right eye is much clearer than my left eye.
However, the recent differences in these two fittings have made me quite anxious...
(I have felt that the accommodative ability of my right eye is slightly worse than that of my left eye, and I have mentioned this issue to the doctors, but they seem to only consider the vision measurement results as normal and think there is no problem).
Could this be due to optic nerve degeneration causing contrast differences? But the degree of optic nerve degeneration in both eyes is similar...
Since my left eye has a higher degree of myopia, it is puzzling that even though I intentionally wore a lower prescription of -950 (which is less than my original soft contact lens prescription of -1000), the clarity is worse than my right eye, yet when I switch back to my glasses, my right eye is normal again.
Is this a sign of presbyopia...? However, the optical shop did not mention presbyopia during the measurements, only myopia and astigmatism, and the ophthalmology clinic also did not bring it up (I am currently 25 years old and am not sure what the cause is).
Thank you, Doctor (I apologize for the many questions).

Xu, 20~29 year old female. Ask Date: 2024/05/26

Dr. Gao Pilin reply Ophthalmology

Hello: Based on the situation you described, there are several possible reasons that could explain your vision fluctuations:
1.
Inconsistent prescription between glasses and contact lenses: You mentioned that the prescriptions for your glasses and contact lenses differ, which may lead to varying visual effects.
Contact lenses typically have a slightly lower prescription than glasses because they sit closer to the cornea, resulting in different optical effects.
Wearing contact lenses with different prescriptions at different times may also require your eyes to adapt.
2.
Unstable refraction: Your refraction data shows some fluctuations in prescription and astigmatism, which is relatively common among individuals with high myopia.
Vision measurements can be influenced by various factors, including fatigue, visual habits, and ambient lighting, all of which can lead to different results during each refraction test.
3.
Accommodation issues: Differences in accommodation ability may also cause inconsistent visual clarity.
Younger individuals usually have stronger accommodation, but prolonged eye strain can affect this function, especially in those with high myopia, where accommodation may be weaker.
If your right eye has poorer accommodation than your left, this could lead to blurriness when viewing objects up close.
4.
Optic nerve degeneration: You mentioned experiencing optic nerve degeneration, which could also affect contrast sensitivity and visual clarity.
Even if the degree of optic nerve degeneration is similar, differences in how each eye responds to and processes light may result in variations in vision.
5.
Dry eye syndrome: Dry eye syndrome can lead to blurred vision, particularly when wearing contact lenses.
You noted that your right eye experiences more severe dryness than your left, which could be one of the reasons for the fluctuations in vision in that eye.
6.
Possible glaucoma: Glaucoma can damage the optic nerve, leading to changes in vision.
Although your visual field test results are normal, regular check-ups are still necessary to monitor the condition of the optic nerve and changes in intraocular pressure.
7.
Presbyopia: Although you are still relatively young, the early signs of presbyopia typically appear around the age of 40.
While presbyopia may not be the cause in your case, regular eye examinations are recommended to rule out other potential issues.
I suggest considering the following measures:
1.
Regular ophthalmic examinations: Continuously monitor the condition of the optic nerve and changes in intraocular pressure to ensure that glaucoma does not worsen.
2.
Stable refraction: Try to have your refraction tests done at the same time of day to reduce measurement errors.
3.
Treatment for dry eye syndrome: If you experience symptoms of dry eyes, you may use artificial tears or other treatments to improve the moisture level of your eyes.
4.
Adjustment of prescription: Communicate with your optician to adjust the prescriptions for your glasses and contact lenses according to your specific needs, ensuring good correction for both near and distance vision.
In summary, your situation may be the result of a combination of factors.
It is advisable to continue monitoring your condition and maintain close communication with your ophthalmologist for timely adjustments and treatment.

Reply Date: 2024/05/26

More Info

Understanding blurry vision while wearing soft contact lenses, especially for individuals with high myopia, can be complex due to various factors that influence vision clarity. High myopia, defined as a refractive error greater than -6.00 diopters, can lead to significant changes in the eye's structure and function, making it essential to monitor any visual disturbances closely.

Firstly, it's important to recognize that the prescription for glasses and contact lenses can differ due to their positioning relative to the eye. Glasses sit approximately 12mm away from the eye, while contact lenses rest directly on the cornea. This difference can lead to variations in the effective power needed for clear vision. For instance, if your glasses are prescribed at -1000 for one eye, the corresponding contact lens prescription may be slightly lower, often requiring adjustments based on the lens design and material.

In your case, the fluctuation in your prescription measurements (e.g., varying degrees of astigmatism and myopia) is not uncommon among individuals with high myopia. Factors such as eye fatigue, hydration levels, and even the time of day can influence the accuracy of refraction tests. Therefore, it is crucial to have your eyes examined under consistent conditions to obtain the most reliable measurements.

The experience of blurry vision in one eye while wearing soft contact lenses could be attributed to several factors:
1. Lens Fit and Type: The fit of the contact lens is critical. If the lens does not sit properly on the cornea, it can lead to discomfort and blurred vision. Additionally, the type of lens (e.g., silicone hydrogel) can affect oxygen permeability, which is vital for corneal health, especially in high myopia patients.

2. Dry Eye Syndrome: You mentioned having mild dry eyes, which can significantly impact vision clarity, particularly when wearing contact lenses. Dryness can lead to inconsistent tear film stability, causing fluctuations in vision. Using lubricating eye drops specifically designed for contact lens wearers may help alleviate this issue.

3. Visual Acuity Differences: The difference in clarity between your left and right eyes could also be due to the inherent differences in their refractive status. If one eye has a higher degree of myopia or astigmatism, it may not focus light as effectively as the other, leading to perceived differences in clarity.

4. Neurological Factors: Given your history of optic nerve issues and potential glaucoma, it is essential to consider that neurological factors could also play a role in how your brain processes visual information from each eye. Even if both eyes have similar degrees of nerve degeneration, the way they adapt to visual stimuli can differ, leading to discrepancies in perceived clarity.

5. Adaptation to Lenses: Transitioning to a new prescription or type of lens can require an adaptation period. If you recently switched to a different lens type or prescription, your eyes may need time to adjust, which can temporarily affect clarity.

6. Potential Early Signs of Presbyopia: While presbyopia typically occurs in individuals over 40, early signs can manifest in younger individuals, especially those with high myopia. If you find that you are struggling to focus on near objects, it may be worth discussing this with your eye care provider.

Given these considerations, it is advisable to schedule a follow-up appointment with your eye care professional. They can conduct a comprehensive examination to assess the fit of your contact lenses, evaluate your tear film quality, and ensure that your prescriptions are appropriate for your current visual needs. Regular monitoring is especially important for individuals with high myopia due to the increased risk of complications such as retinal detachment or glaucoma.

In summary, blurry vision while wearing soft contact lenses in the context of high myopia can arise from multiple factors, including lens fit, dry eye syndrome, and inherent differences in refractive status. A thorough evaluation by an eye care professional will help identify the underlying causes and guide appropriate management strategies to optimize your visual experience.

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