Does Wearing Glasses Over Prescription Increase Farsightedness?

Doctor

I have been wearing glasses that are 100 degrees stronger than my original prescription (currently 950 degrees, wearing 1050 degrees).
People say this will cause me to become farsighted.
Is that true? Does this mean I can still read up close without any issues? I am used to reading and using the computer in the dark; which one would increase my prescription more? When I had my prescription checked, it didn't increase, which means I can continue wearing these glasses.
I was also told by an optician that wearing glasses that are more than 100 degrees stronger will only increase pseudomyopia and not my actual prescription, so I shouldn't worry.
Is what she said correct?

amy, 20~29 year old female. Ask Date: 2002/10/01

Dr. Chen Xuan reply Ophthalmology

Myopia of 950 degrees refers to the condition where, when viewing objects at a distance greater than five meters (essentially at infinity), a -9.5 diopter concave lens is required to focus the image clearly on the retina.
When looking at objects within five meters, the ciliary muscles (the small muscles surrounding the lens) must contract to increase the curvature of the lens (which acts like a convex lens) in order to project the image clearly.
This allows our eyes to adjust focus instantaneously, similar to an autofocus camera, relying entirely on the contraction and relaxation of the ciliary muscles.
However, prolonged near work can lead to fatigue of the ciliary muscles, resulting in temporary loss of elasticity and causing pseudomyopia.

Therefore, if you typically wear glasses with a prescription stronger than your actual refractive error while primarily engaging in near work (within five meters), you are increasing the burden on your eyes (ciliary muscles) from the outset.
For a developing eye (such as that of a ten-year-old child), this can lead to "myopization" of the eye, where the eye grows longer along the visual axis.
In contrast, for an adult eye that has stopped growing (such as a thirty-year-old), prolonged near work may not necessarily increase the refractive error but can result in symptoms such as eye strain, headaches, and blurred vision.

Additionally, when reading or using a computer, it is advisable not to turn off all indoor lighting; some background illumination should be maintained.
When reading, it is best to have a warm, stable light bulb positioned in the left front area (for right-handed individuals) to avoid increasing the strain on the eyes.

Reply Date: 2002/10/01

More Info

Wearing glasses that are over your prescribed prescription can indeed have implications for your vision, but the relationship between wearing stronger lenses and the development of farsightedness (hyperopia) is not straightforward.
When you wear glasses that are stronger than your actual prescription, your eyes may become accustomed to the increased power of the lenses. This can lead to a phenomenon known as "accommodative spasm," where your eye muscles may overwork to compensate for the excess power. While this does not directly cause your eyes to become more farsighted, it can lead to visual discomfort, eye strain, and potentially exacerbate existing vision problems.

In your case, wearing glasses with a prescription of -10.50 diopters (which indicates high myopia or nearsightedness) when your actual prescription is -9.50 diopters may not necessarily lead to an increase in your degree of myopia or cause you to develop hyperopia. However, it can lead to discomfort, headaches, and difficulty focusing, especially when looking at objects at varying distances.
Regarding your habits of reading in the dark or using a computer, these activities can contribute to eye strain, especially if you are not using the appropriate lighting. Reading in low light conditions can make your eyes work harder, leading to temporary discomfort and fatigue. This does not directly cause an increase in your prescription but can lead to symptoms that may feel like a worsening of your vision.
The claim that wearing glasses that are over your prescription will only lead to "pseudomyopia" (a temporary condition where the eye appears more nearsighted due to spasm of the focusing muscles) is partially accurate. Pseudomyopia can occur, but it is essential to understand that it is not the same as a permanent increase in your actual refractive error.
If your prescription has not changed during your eye exams, it suggests that your myopia is stable at this time. However, it is crucial to have regular check-ups with your eye care professional to monitor any changes in your vision and ensure that your prescription is appropriate for your needs.
In summary, while wearing glasses that are stronger than your prescription may not directly cause an increase in farsightedness, it can lead to discomfort and visual strain. It is essential to use the correct prescription for your eyes to avoid unnecessary strain and maintain optimal visual health. If you have concerns about your vision or the effects of your current glasses, it is advisable to consult with an eye care professional for personalized advice and recommendations.

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