the Differences Between Spherical and Aspherical Lenses in Eyewear

Spherical and aspherical lenses?

Hello Dr.
Liang,
Recently, I got a pair of non-spherical glasses, and the frame is about twice the size of my previous pair.
After wearing them, I noticed that the clarity is affected in dim lighting conditions.
Additionally, as a software engineer, I have to stare at the screen for long periods.
When I wear the new glasses and then look at distant hills after focusing on the screen for a while, my vision becomes blurry, and it takes about 5 to 8 seconds for my vision to clear up.
However, when I wear my old glasses, my vision is clear.
When I switch back to the old spherical glasses, I do not experience this blurriness when looking at distant hills.
I would like to know how to address this situation.
I have read online, and many people speculate that it might be due to an incorrect focal length of the new glasses.
Additionally, when wearing the old glasses, I can clearly see the electronic timetable at the train station (red and green lights) without any blurry halos, but with the new glasses, I do experience this issue.
I took both pairs of glasses to another optical shop for testing, and both pairs yielded the same measurements for prescription and astigmatism.
However, the experience of wearing them is completely different.

Could you please advise me on what might be causing this issue? Thank you.

Chenson, 40~49 year old female. Ask Date: 2018/12/10

Dr. Liang Ce reply Ophthalmology

It is recommended that you visit an ophthalmology clinic to discuss your condition in detail.
The physician will provide appropriate management.
Wishing you good health.

Reply Date: 2018/12/10

More Info

Understanding the differences between spherical and aspherical lenses in eyewear is crucial, especially for individuals like yourself who spend long hours in front of screens. Let's delve into the characteristics of these lenses and how they might be affecting your vision.

Spherical Lenses: These lenses have a uniform curvature across their entire surface. This means that the lens has the same optical power in all directions, which can be beneficial for correcting simple refractive errors like myopia (nearsightedness) and hyperopia (farsightedness). However, spherical lenses can cause some optical distortions, particularly at the edges, which may lead to a narrower field of view and potential blurriness when looking away from the center of the lens.

Aspherical Lenses: In contrast, aspherical lenses have a more complex surface profile that gradually changes in curvature from the center to the edges. This design allows for a wider field of view and reduces distortion, especially for higher prescriptions. Aspherical lenses are particularly advantageous for individuals with significant refractive errors, as they can provide clearer vision across the entire lens surface and minimize the "fishbowl" effect often associated with thicker spherical lenses.

Given your experience with the new aspherical lenses, it seems you are encountering some challenges that could stem from several factors:
1. Adaptation Period: Transitioning from spherical to aspherical lenses may require an adaptation period. The brain needs time to adjust to the new way light is being focused through the lenses. This adjustment can take a few days to weeks, depending on the individual.

2. Lens Design and Prescription: Even if the prescription measurements are the same, the design of the lenses can significantly impact visual clarity. Aspherical lenses, while beneficial, may not work optimally if the fitting height or alignment is not correct. If the optical center of the lens does not align with your pupil, it can lead to blurred vision and discomfort.

3. Distance Vision Issues: The blurriness you experience when switching from looking at a screen to viewing distant objects could be related to the lens design. Aspherical lenses can sometimes create a different focal point, especially if they are designed for specific distances (like reading or computer work). If you are primarily using them for close work, your eyes may need to refocus when looking at distant objects, which can cause temporary blurriness.

4. Light Conditions: You mentioned that the clarity is affected by dim lighting. Aspherical lenses can sometimes be more sensitive to lighting conditions, particularly if they are not treated with anti-reflective coatings. This coating helps reduce glare and improves clarity in low-light situations.

5. Optical Quality: The quality of the lens material and the manufacturing process can also play a role. Higher-quality aspherical lenses typically provide better optical performance, so it may be worth discussing with your optometrist if the lenses you received meet high standards.

To address your concerns, here are some recommendations:
- Follow-Up with Your Optometrist: Schedule a follow-up appointment to discuss your experiences with the new lenses. They can assess the fit and alignment and make adjustments if necessary.

- Give It Time: Allow yourself a reasonable adaptation period. If the issues persist beyond a few weeks, it may be time to reconsider the lens type or prescription.

- Consider Anti-Reflective Coatings: If your new lenses do not have an anti-reflective coating, consider getting them treated. This can enhance clarity and reduce glare, especially in varying light conditions.

- Evaluate Your Workstation: Ensure that your workstation is ergonomically set up to minimize strain on your eyes. Adjust the screen brightness and contrast to comfortable levels, and take regular breaks to reduce eye fatigue.

In conclusion, the differences between spherical and aspherical lenses can significantly impact your visual experience, especially in a profession that demands prolonged screen time. By understanding these differences and working closely with your eye care professional, you can find the best solution for your vision needs.

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