When you need glasses to correct your vision, every so often your prescription changes. Rare is the person who can go many years with the same eyeglasses. Usually you will be able to get used to new glasses within a day or two, but occasionally it will take longer. If your new prescription is for bifocals or progressive lenses and you haven't worn that type of glasses before, you can expect a slightly longer period of adjustment, but it still should not take more than a few days to get used to the new prescription.
When you are having trouble getting used to new glasses, you may suffer from blurred vision, dizziness, eye strain, or headaches. If these problems persist for longer than a few days, you need to investigate the cause. Most likely it is an error in either the original prescription or in making the lenses. Another possibility is that you need a different type of lens.
If you are switching to bifocals or progressive lenses, ask the optician for instructions on using them properly. These types of lenses require unfamiliar movements of the head and eyes to look through different areas of the lenses. The specific area of the lens you look through changes, depending on whether you are reading, using a computer monitor, or viewing objects at an intermediate or far distance.
Wear your new glasses every day. Switching back and forth between your old and new glasses will only hinder you getting used to the new ones.
Take the glasses back to the optician who made them if you aren't used to them within a few days. The optician will check the prescription against the lenses to verify that they were made properly. If it turns out the glasses were not ground correctly, the optician should make you a new pair of glasses at no additional cost.
Bring the glasses to the optometrist or ophthalmologist who wrote the eyeglass prescription. The eye doctor will check the glasses to ensure they were made to the specified prescription. If the glasses were made properly, the eye doctor will recheck your vision and write a new prescription if the original prescription was inaccurate.
Ask the optician to tell you what kind of material your lenses are made of and whether your old lenses are made of the same or a different material. Eyeglass lenses are available in many different types of materials and are made by many different manufacturers. If your old and new lenses are made of different materials, you may find that you cannot adapt to the new lens material and need to have the glasses remade with another type of lenses.
If the prescription you received from your eye doctor was typed into the optician's computer system or even copied by hand onto an order form, have the optician check that the prescription was transcribed correctly. An error made at this point will result in glasses that are not made to your actual prescription.