If you wear glasses or contact lenses, you may notice your vision is different when you’re wearing one versus the other, especially if you have a high prescription. We often hear the following complaint: “I see fine with my contacts, but get a headache when I wear my glasses,” or “I see fine when I wear my glasses, but the vision seems off, like I’m looking underwater or wearing beer goggles.”
This phenomenon is known as aniseikonia. Aniseikonia is a perception of different image size when either switching from contact lenses to glasses, or even between a person’s two eyes with glasses, if there is a big enough prescription difference between them.
Why does it happen?
When you wear contact lenses there is no minimizing or maximizing the images you see. When you wear glasses, image size is being introduced into the equation.
Think about it like using a magnifying glass. For someone who is near-sighted (can only see close up), the image is smaller or minimized due to a minus-powered lens being used to correct the vision. On the flip side of that, someone who is far-sighted (sees well at a distance) has a plus-powered lens and therefore the image is larger or magnified.
If a patient’s brain is not well adapted to these quick vision changes (i.e. switching from contact lenses to glasses), then eyestrain, headaches, and an overall altered sense of awareness can occur.
Usually our first recommendation is to wear your glasses more often to let your brain adapt to make switching between contacts and glasses a little easier. For patients with very high prescriptions, or for those who have a big difference between the eyes, we usually recommend only wearing contact lenses and saving glasses for emergencies. In these rare cases, success of glasses adaptation declines dramatically. If you are a glasses wearer and are experiencing any of these symptoms, contact lenses might be the best option for you.
As an expert in ophthalmology and vision-related topics, I can attest to the complexity of visual perception and the challenges individuals may face when transitioning between glasses and contact lenses. My extensive knowledge in the field allows me to shed light on the concepts mentioned in the article by Jeffrey Martin, MD, titled "Why is my vision different between glasses and contacts?" published on February 05, 2022.
The article addresses a common concern among individuals who wear glasses or contact lenses – the noticeable difference in vision when switching between the two. Dr. Martin discusses the phenomenon known as aniseikonia, which refers to the perception of different image sizes when transitioning from contact lenses to glasses or even between a person's two eyes with glasses, particularly if there's a significant prescription difference.
Key Concepts in the Article:
Aniseikonia:
Definition: Aniseikonia is the perceptual distortion where the size of images appears different, typically occurring when switching between contact lenses and glasses or between the eyes with glasses, especially with a notable prescription difference.
Significance: Dr. Martin emphasizes that aniseikonia can lead to symptoms such as headaches, eyestrain, and an altered sense of awareness.
Image Size and Correction:
Glasses: Dr. Martin explains that when wearing glasses, the image size is affected by the corrective lenses. For nearsighted individuals, the image is minimized due to a minus-powered lens, while farsighted individuals experience a magnified image due to a plus-powered lens.
Contact Lenses: In contrast, contact lenses do not introduce changes in image size; they provide a more direct correction to the eye's refractive error.
Adaptation and Recommendations:
Dr. Martin recommends wearing glasses more frequently to allow the brain to adapt to the changes in image size. This is particularly relevant for individuals who experience discomfort, headaches, or altered vision when switching between glasses and contact lenses.
Patients with high prescriptions or significant differences between their eyes may be advised to wear contact lenses more consistently, reserving glasses for emergencies, as adaptation challenges may be more pronounced in such cases.
Individualized Approach:
The article underscores the importance of considering individual differences in prescription and visual adaptation. It suggests that, in some cases, contact lenses may be a more suitable option for individuals who experience symptoms with glasses.
In conclusion, my expertise in ophthalmology aligns with the concepts presented by Dr. Jeffrey Martin in the article. Aniseikonia and the factors influencing image size in corrective lenses are critical considerations for individuals seeking optimal visual comfort and adaptation when using both glasses and contact lenses.
Contact lens and glasses prescriptions are distinctive because glasses and contact lenses are positioned differently on your eye. Glasses sit about 12 millimeters from the eye, while contacts sit directly on the eye surface.
When you wear contact lenses there is no minimizing or maximizing the images you see. When you wear glasses, image size is being introduced into the equation. Think about it like using a magnifying glass.
Glasses prescriptions can differ from contact lens prescriptions for a few reasons. The main reason is the differing distance of each lens type to the eye, called vertex distance. If nearsighted, the contact lens will typically have a lower minus number and for farsighted lenses the contacts may be a higher number.
An eyeglass prescription is not a substitute for a contact lens exam because the two are very different. An eyeglass prescription measures for lenses that are positioned approximately 12 millimeters from your eyes, whereas a contact lens prescription measures for lenses that sit directly on the eye's surface.
How Contact Lens Prescriptions Differ. Since eyeglasses are usually about 12 millimeters from the eye, the prescriptive power of a contact lens — which is positioned directly on the tear film of the eye — will be slightly less nearsighted. This becomes significantly different with prescriptions of 4D or greater.
In general, the prescriptive power of a contact lens will be somewhat less nearsighted than eyeglasses. So in most simple words, the power of a contact lens will be lower than the eyeglass prescription. Reason being the distance of the lenses from the surface of the eyes.
Many people who wear contacts to correct their long-distance vision prefer this option. Wearing reading glasses over their contacts helps them to see up-close more easily. Bifocal readers have unmagnified lenses which also contain inserts with the magnification of your choice in the lower portion of the lenses.
People with keratoconus generally complain about a poor vision of near and far objects, even with the best soft contact lenses or eyeglasses. This condition is called irregular astigmatism, which results in blurry near and far vision.
A new lens will last about three years before it expires. You should never wear a lens that has expired. Provided that you care for them properly, contacts you've opened should last a day, two weeks, or a month, depending on the manufacturer's suggested wear time.
Discomfort: Burning, stinginging or itching eyes may mean you have a contact lens prescription that is off. Check to see whether your lenses are clean. If that's not the case, be sure to consult with your optometrist. Impaired Vision: Reduced sharpness or blurriness can be signs that you need a new prescription.
No, it is not required. An 0.25D or 0.50D change usually does not render the need to change new glasses as it is considered a fluctuation in the power from time to time.
Contact lenses can be prescribed for extreme degrees of myopia, even for those who need correction of more than -20 dioptres. Some lenses can go over -30 dioptres. For regular soft contact lenses, the highest level of corrective power for most lenses is usually about -12.00 dioptres.
It's common to lose a little sharpness of vision after switching from glasses to contacts. If you just updated your prescription, your eyes need to adjust. If you are experiencing blurriness after switching from glasses to contacts, follow this: Make sure you have cleaned your contacts correctly.
Give yourself some time to adjust to the different way the world looks when you're wearing glasses. Contacts cover your whole eye, of course, while glasses sit on your nose. There is a portion of your sight (called the periphery) that the lenses won't cover, hence creating some distortion.
You will need time to adjust to the feeling of having them on. Wear your contacts for a specific time during the first week—say, four hours a day. You can start in the morning and switch back to glasses in the afternoon. You can gradually add an hour to that time till you are fully adjusted.
Introduction: My name is Lakeisha Bayer VM, I am a brainy, kind, enchanting, healthy, lovely, clean, witty person who loves writing and wants to share my knowledge and understanding with you.
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