Your Eyeglass Prescription: Key Questions Answered

Q: Your Eyeglass Prescription: Key Questions Answered

Hello, Ah-Hsiang： 1. A difference of 25 degrees is not a problem. 2. Having two eyes will naturally provide better overall vision. It can also be said that they complement each other. 3. There will be no adverse effects. 4. As long as it is comfort

Consultation on Eyeglass Prescription Concerns

Dear Dr.
Gao,
Hello.
My left eye has a prescription of approximately -300 degrees with astigmatism of about -50 or -75 degrees; my right eye is around -400 degrees with astigmatism of about -100 degrees.
I have been wearing this prescription for nearly 20 years, and I can see clearly both near and far, and it feels comfortable.
Last year (2021), I went to an optical shop to replace my lenses (due to delamination of the lenses).
During the eye exam, the prescription for my left eye remained unchanged, but the prescription for my right eye needed to be increased by 25 degrees, as the optician said that this would improve clarity.
However, after I started wearing the new lenses, I experienced a slight magnification effect and felt somewhat uncomfortable (which could also be psychological).
After trying them for a day or two without being able to adapt, I requested to switch back to my old prescription, which means my right eye lens is now under-corrected by 25 degrees.
However, after the change, it felt much more comfortable, and I have been wearing them since.
I have the following questions for you, Dr.
Gao:
Q1.
Currently, with my glasses, I can see clearly with both eyes for near vision; however, when looking far with just my right eye, it appears somewhat blurry, while my left eye sees more clearly.
In your opinion, is it acceptable for me to wear these glasses with the right eye under-corrected by 25 degrees? Given that my right eye does appear blurrier for distance, could this lead to any adverse effects on my right eye in the long term (such as increased intraocular pressure, worsening myopia or astigmatism, or eye fatigue)?
Q2.
When I wear these glasses and use both eyes together, I can see clearly and comfortably for both near and far.
Can you explain the principle behind this? Is it because my left eye compensates for the blurrier vision of my right eye?
Q3.
Following up on the previous question, if it is indeed the case that my left eye compensates for the blurrier vision of my right eye, could this long-term compensation lead to any adverse effects on my eyes, especially my left eye (such as increased intraocular pressure, worsening myopia or astigmatism, or eye fatigue)? I feel that my left eye may be exerting more effort to compensate for the blurriness of the right eye to maintain overall clarity for both near and far vision.
Q4.
I came across an article online that mentioned: "Since lens prescriptions are typically increased in increments of 25 degrees, sometimes when a wearer increases by one increment, it feels too strong, while decreasing by one increment results in unclear vision.
In such cases, the dominant eye's prescription is usually made stronger." My dominant eye is my right eye, and I indeed felt that increasing by one increment (25 degrees) made it too strong and uncomfortable, while decreasing by one increment (25 degrees) made distant vision somewhat blurry.
Ultimately, I chose to have my dominant right eye's lens under-corrected by 25 degrees for comfort, which contradicts the article's suggestion of making the dominant eye's prescription stronger.
In your opinion, is my choice correct (i.e., under-correcting my dominant right eye's lens by 25 degrees for comfort), or should I follow the article's advice to make the dominant eye's prescription stronger?
Thank you, Dr.
Gao.

Axiang, 40~49 year old female. Ask Date: 2022/06/06

Dr. Gao Pilin reply Ophthalmology

Hello, Ah-Hsiang: 1.
A difference of 25 degrees is not a problem.
2.
Having two eyes will naturally provide better overall vision.
It can also be said that they complement each other.
3.
There will be no adverse effects.
4.
As long as it is comfortable and both eyes' vision is acceptable, there is no need to be overly concerned.

Reply Date: 2022/06/06

More Info

Dear Patient,
Thank you for your detailed questions regarding your eyeglass prescription and the concerns you have about your vision. I appreciate your trust in seeking clarification on these important matters. Let’s address your questions one by one.

Q1: Regarding your current eyeglasses, it seems that you are experiencing some blurriness when using your right eye for distance vision, which is concerning given that you have reduced the prescription by 25 degrees. While it is possible to wear glasses that are less than the prescribed strength, doing so may lead to visual discomfort or strain, particularly if your right eye is not receiving the optimal correction. Over time, this could potentially lead to increased eye fatigue, and while it is unlikely to directly cause an increase in intraocular pressure or worsen your refractive error, it may contribute to discomfort and visual strain. If you find that your right eye is consistently blurry, it would be advisable to consult with your eye care professional to reassess your prescription.

Q2: When you use both eyes together, your brain is capable of combining the visual input from both eyes, which can sometimes compensate for the weaker eye. This phenomenon is known as binocular summation, where the brain integrates the clearer image from your left eye with the less clear image from your right eye, allowing for an overall improved perception of clarity. This is why you may find that using both eyes together feels comfortable, even if one eye is not fully corrected.

Q3: While your left eye may be compensating for the right eye's blurriness, this does not typically lead to adverse effects such as increased intraocular pressure or worsening refractive errors in the left eye. However, it could lead to increased fatigue in the left eye over time, as it is working harder to provide clear vision. It is essential to monitor any discomfort or visual changes and to ensure that both eyes are receiving appropriate correction to minimize strain.

Q4: Your decision to reduce the prescription in your dominant eye (the right eye) for comfort is understandable, especially if the increased prescription felt too strong. However, it is generally recommended that the dominant eye be corrected to the full prescription to ensure optimal visual acuity, particularly for distance vision. The discomfort you experienced with the increased prescription could indicate that it was indeed too strong for your visual needs. It is important to find a balance between comfort and clarity. If you feel that your current setup is providing you with satisfactory vision and comfort, it may be acceptable for your personal situation, but I would recommend discussing this with your eye care provider to ensure that your visual health is not compromised.

In summary, while comfort is essential, it is also crucial to ensure that your vision is adequately corrected to prevent long-term issues. Regular follow-ups with your eye care professional will help monitor your vision and make necessary adjustments to your prescription as needed. If you continue to experience discomfort or changes in your vision, please do not hesitate to seek further evaluation.

Best wishes for your eye health, and thank you for your thoughtful questions.

Sincerely,
Doctor Q&A Teams

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