Why Can't I Achieve 20/20 Vision Even with Glasses?

Why is it that after getting glasses, vision still cannot be corrected to 1.0?

Hello, I was diagnosed with amblyopia in my childhood (with astigmatism of about 200 degrees in both eyes).
After correction, by the age of 12, my astigmatism reduced to 125 in the left eye and 75 in the right eye (with no myopia), and my uncorrected vision in both eyes was 1.2.
However, after starting high school, I began to notice that things were becoming increasingly blurry.
At 18, an examination revealed that my astigmatism had increased to 275 in the left eye and 125 in the right eye.
After starting college, I had to get a new prescription due to my glasses breaking, and I found that my prescription had further increased to 375 astigmatism and -50 myopia in the left eye, and 200 astigmatism and -50 myopia in the right eye.
With the new glasses, my left eye can only see 0.7.
What could be the reason for this? Is my vision likely to continue to deteriorate?

Nì míng, 10~19 year old female. Ask Date: 2016/12/09

Dr. Cai Wenyuan reply Ophthalmology

Hello, there are many factors that can affect vision, so it should not be difficult to identify the cause.
It is recommended to have regular medical check-ups.
Wishing you safety and health.
Sincerely, Dr.
Tsai Wen-Yuan, Director of the Ophthalmology Department, Taoyuan General Hospital, Ministry of Health and Welfare.

Reply Date: 2016/12/09

More Info

Achieving 20/20 vision is often considered the gold standard for visual acuity, but various factors can prevent individuals from reaching this level, even with corrective lenses. In your case, the history of amblyopia (commonly known as "lazy eye") and the presence of astigmatism are significant contributors to your current visual challenges.

Understanding Your Condition
1. Amblyopia: This condition typically develops in childhood when the brain favors one eye over the other. It can result from various factors, including strabismus (crossed eyes) or significant differences in refractive error between the two eyes. Even after treatment, amblyopia can lead to permanent visual deficits, making it difficult to achieve optimal vision, even with corrective lenses.

2. Astigmatism: This refractive error occurs when the cornea or lens of the eye is irregularly shaped, causing blurred or distorted vision. Your increasing astigmatism, as indicated by your prescription changes, suggests that your eyes may be undergoing structural changes that affect how light is focused on the retina. The increase in astigmatism from 200 degrees to 375 degrees in your left eye is particularly concerning and may indicate a progression of your condition.

3. Myopia (Nearsightedness): The presence of myopia, even at a mild level (50 degrees), can further complicate your visual acuity. When combined with astigmatism, it can create a scenario where corrective lenses may not fully compensate for the visual deficits.

Why You Might Not Achieve 20/20 Vision
1. Limitations of Corrective Lenses: Glasses can correct refractive errors to a certain extent, but they cannot address underlying issues such as amblyopia. If your brain has not developed the ability to use both eyes effectively, even the best corrective lenses may not enable you to see at 20/20.

2. Changes in Eye Structure: As you age, the shape of your eyes can change, leading to fluctuations in your refractive error. This is particularly common in individuals with a history of amblyopia and astigmatism. Regular eye exams are crucial to monitor these changes and adjust your prescription accordingly.

3. Visual Processing: The brain's ability to process visual information from both eyes can be affected by amblyopia. If one eye is dominant, the brain may not fully utilize the input from the other eye, leading to suboptimal visual acuity.

Recommendations
1. Regular Eye Exams: It is essential to have regular check-ups with an eye care professional. They can monitor your vision changes and adjust your prescription as needed. If you notice any sudden changes in your vision, seek immediate attention.

2. Consider Contact Lenses: Sometimes, contact lenses can provide better visual acuity than glasses, especially for individuals with significant astigmatism. They sit directly on the eye and can reduce distortions caused by the lens of the glasses.

3. Vision Therapy: Depending on your specific situation, vision therapy may be beneficial. This is a structured program of visual activities designed to improve visual skills and processing. It is particularly helpful for individuals with amblyopia.

4. Surgical Options: In some cases, refractive surgery (like LASIK) may be an option to correct significant refractive errors. However, this is typically considered after thorough evaluation and discussion with an eye care specialist.

5. Healthy Eye Habits: Maintain a healthy lifestyle that includes a balanced diet rich in vitamins A, C, and E, omega-3 fatty acids, and antioxidants. Protect your eyes from UV exposure and practice good screen habits to reduce eye strain.

Conclusion
While achieving 20/20 vision may be challenging due to your history of amblyopia and increasing astigmatism, it is essential to remain proactive about your eye health. Regular consultations with your eye care provider, along with appropriate corrective measures, can help you maintain the best possible vision. Remember, visual acuity is just one aspect of vision; quality of life and functional vision are equally important.

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