Eye Exams: Differences Between Refraction and Dilation

Q: Eye Exams: Differences Between Refraction and Dilation

Hello： 1. <br>It is quite common to experience a slight increase in prescription during high school, especially after prolonged reading or eye use. <br>This may be related to changes in myopia, but it does not necessarily indicate pseudomyopia. <br>To gain a clearer understanding

Vision examination

Hello, doctor.
A few days ago, I got new glasses, and my prescription increased by less than one diopter in each eye, while my astigmatism remains unchanged at 2.00.
I've heard that it's quite normal for prescriptions to increase slightly during high school, and I haven't changed my lenses in many years.
However, since I'm preparing for the university entrance exam, I've been spending a lot of time in the library since last July, often studying for 1 to 3 hours after school.
I would like to ask:
1.
Is there a high possibility that the increase in my prescription includes pseudomyopia?
2.
I plan to visit an ophthalmologist for an eye examination, but I've been searching for a long time and still can't clearly distinguish between dilation tests and refraction tests.
When I went to the optical shop, the staff helped me with the refraction test.
Will the refraction test at the ophthalmologist's office be more accurate? Is the purpose of the refraction test just to confirm the prescription or the angle? It seems that distinguishing between true and false myopia requires some dilation; is this part of the refraction test?
3.
It's often said that regular eye examinations are necessary.
For high myopia, should the regular check-ups include a refraction test, or is a dilation examination better?

Cy, 10~19 year old female. Ask Date: 2024/01/19

Dr. Gao Pilin reply Ophthalmology

Hello: 1.
It is quite common to experience a slight increase in prescription during high school, especially after prolonged reading or eye use.
This may be related to changes in myopia, but it does not necessarily indicate pseudomyopia.
To gain a clearer understanding, it is recommended to visit an ophthalmologist for a comprehensive examination and assessment.
2.
Refraction is the procedure used to determine your current prescription, while cycloplegic refraction involves relaxing the eyes before testing, which can eliminate the effects of pseudomyopia.
3.
For individuals with high myopia, it is advisable to have regular eye examinations to ensure eye health.
This may include routine refraction and cycloplegic examinations to monitor changes in prescription and the health of the internal structures of the eye.
Cycloplegic examination is particularly important for detailed observation of the fundus in patients with high myopia.

Reply Date: 2024/01/19

More Info

Hello! Thank you for your questions regarding eye exams and the differences between refraction and dilation. It’s great that you’re taking an active interest in your eye health, especially as a student who spends a lot of time studying. Let’s break down your questions one by one.

1. Possibility of Pseudomyopia: Pseudomyopia, or "false myopia," can occur when the eye's focusing system is overworked, often due to prolonged near work, such as reading or studying for long hours. This condition can lead to temporary nearsightedness, which may resolve when the eyes are rested. Given your study habits, it is indeed possible that the slight increase in your prescription could be influenced by pseudomyopia. However, it’s essential to have a comprehensive eye exam to determine whether this is the case or if there is a genuine progression in your myopia.

2. Difference Between Refraction and Dilation: Refraction is the process used to determine your glasses prescription. During a refraction test, an eye care professional uses a phoropter or an autorefractor to measure how light rays are bent as they enter your eye, helping to identify the correct lens power needed for clear vision. This test is typically performed without dilation.

Dilation, on the other hand, involves the use of special eye drops to widen your pupils. This allows the eye doctor to examine the internal structures of your eyes, including the retina and optic nerve, for any signs of disease or abnormalities. Dilation can also help in assessing the overall health of your eyes, which is particularly important for individuals with high myopia, as they are at a greater risk for retinal issues.

While the refraction done at an optical shop can provide a good estimate of your prescription, an eye exam at an ophthalmologist's office, especially with dilation, offers a more comprehensive evaluation of your eye health. Dilation is not typically considered part of the standard refraction process but is crucial for a thorough examination.

3. Regular Eye Exams for High Myopia: For individuals with high myopia, regular eye exams are essential. These exams should include both refraction and dilation. The reason for this is that high myopia increases the risk of developing complications such as retinal detachment, glaucoma, and cataracts. Regular dilated eye exams allow your eye doctor to monitor the health of your retina and other internal structures, ensuring that any potential issues are caught early.

In summary, it’s important to have a comprehensive eye exam that includes both refraction and dilation, especially given your increased prescription and study habits. This will help determine whether your vision changes are due to pseudomyopia or a genuine increase in myopia. Regular check-ups are crucial for maintaining eye health, particularly for those with high myopia. If you have any further questions or concerns, don’t hesitate to reach out to your eye care provider. They can provide personalized advice based on your specific situation. Take care of your eyes, especially during your studies!

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