Myopia and Astigmatism: When to Wear Glasses and Degree Variations

Timing and Prescription Issues for Eyeglasses

I started experiencing myopia around the 9th grade to the 11th grade, with an initial prescription of approximately -2.00 diopters of myopia and -0.75 diopters of astigmatism.
After undergoing cycloplegic refraction, the results were similar.
During college, when I got new glasses, I found my prescription had changed to -1.25 diopters of myopia and -1.00 diopters of astigmatism.
Last year, when I went to an optical store for new glasses, the result was -1.00 diopters of myopia and -1.00 diopters of astigmatism.
A few days later, I went to another branch for a re-examination, and the optometrist there gave me a trial pair of glasses with a prescription of -1.25 diopters, which felt fine, so I changed my prescription.
However, three months later, when I went to another optical store for another refraction, the results showed -1.50 diopters of myopia and -1.25 diopters of astigmatism.
Ultimately, I ended up with glasses prescribed at -1.50 diopters of myopia and -1.25 diopters of astigmatism, which I have been wearing without any significant discomfort and with clear vision.
1.
Isn't it true that the cycloplegic refraction indicates the true degree of myopia? Why did my prescription decrease afterward? Could it be that the cycloplegic effect was not fully achieved, or has my axial length actually shortened?
2.
Is the prescription of -1.00 diopters of myopia from the optical store the true measurement? Or is -1.25 diopters or -1.50 diopters the accurate one? Could there be measurement errors? Why do the results vary so much between different optical stores? I was well-rested and had not used my eyes before the tests, and there was minimal disparity between both eyes, with only about a 0.25 diopter difference in astigmatism.
3.
I usually only wear glasses when going out and do not wear them at home.
Is it better for my eyes to wear them consistently? Thank you, doctor.

Jason, 20~29 year old female. Ask Date: 2021/03/07

Dr. Gao Pilin reply Ophthalmology

Hello Jason,
1.
The axial length should not shorten; this phenomenon may occur if the dilation is not complete.
Additionally, the difference is minimal, and sometimes the refractor can have some errors.

2.
An error of 25-50 degrees is possible.

3.
You are currently 25 years old, and based on your habits, you should do what feels comfortable for you.
If you are not used to wearing glasses and have no issues in your daily life, it is fine not to wear them.
You can wear them when you need good vision.

The ophthalmology department at Puzi Hospital in Taiwan is open:
Monday, Tuesday, Thursday, and Friday from 8:00 AM to 12:00 PM
Wednesday from 2:00 PM to 4:30 PM
Please note that online responses can only serve as a reference; it is necessary to visit a medical institution for proper care.
I hope to have the opportunity to assist you.

Best regards,
Gao Pilin

Reply Date: 2021/03/07

More Info

Understanding myopia (nearsightedness) and astigmatism can be quite complex, especially when it comes to determining the right prescription for glasses. Your experience with fluctuating prescriptions raises several important points that are worth discussing.

1. Understanding the Role of Cycloplegic Refraction: Cycloplegic refraction, which is often performed using eye drops to temporarily paralyze the ciliary muscle, allows for a more accurate measurement of refractive errors, particularly in children and young adults. This method helps to determine the "true" refractive error without the influence of accommodation (the eye's ability to focus on near objects). However, it is important to note that the results can vary based on several factors, including the individual’s eye health, the specific drops used, and the timing of the examination. If your prescription changed after a cycloplegic refraction, it could indicate that your eyes were not fully relaxed during the initial tests, or that your refractive error has genuinely changed over time.

2. Variability in Prescription Measurements: The differences in prescriptions you’ve encountered at various optical shops can be attributed to several factors. Each optician may use different equipment, techniques, or even subjective assessments during the refraction process. Variability can also arise from the testing environment, such as lighting conditions or the patient's level of fatigue. It's not uncommon for individuals to receive slightly different prescriptions from different practitioners. The key is to find a prescription that provides clear vision without discomfort. If you feel comfortable with the 150-degree myopia and 125-degree astigmatism glasses, that may be the best option for you, even if it differs from previous measurements.

3. Wearing Glasses Regularly: Regarding your question about whether you should wear glasses all the time, it largely depends on your lifestyle and visual needs. If you find that you see clearly and comfortably with your glasses, wearing them can help reduce eye strain, especially during activities that require good distance vision, such as driving or attending classes. However, if you are comfortable without them at home and do not experience significant visual discomfort, it is acceptable to wear them only when necessary. That said, consistent use of corrective lenses can help maintain visual clarity and potentially slow the progression of myopia, especially in younger individuals.

4. Monitoring Eye Health: Given your history of fluctuating prescriptions, it is essential to have regular eye exams to monitor your eye health and refractive status. Changes in your prescription can sometimes indicate underlying issues, such as changes in the shape of your cornea or the length of your eyeball, which can occur with myopia. Regular check-ups will help ensure that any significant changes are addressed promptly.

In summary, the variability in your prescriptions can be attributed to several factors, including the method of measurement and the conditions under which the tests were conducted. It is crucial to find a prescription that provides you with the best visual comfort and clarity. Regular eye examinations will help you keep track of your eye health and any changes in your vision. If you have any concerns about your vision or eye health, it is always best to consult with an eye care professional who can provide personalized advice based on your specific situation.

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