What Are Prism Lenses and How Do They Help Double Vision?
Double vision, or diplopia, happens when your eyes aren't working together properly. Instead of both eyes focusing on the same point, they're slightly misaligned, so your brain receives two slightly different images. Prism lenses bend light rays before they enter your eyes, helping to realign what you're seeing so your brain receives just one clear image instead of two.
Prisms don't correct the underlying eye misalignment itself. Instead, they compensate for it, making it easier for your eyes to work together. Think of it like adjusting the angle of a picture frame so both sides line up perfectly. When you come in for an eye exam at Vision Palace Optical on Avenue U, Dr. Sheyko or Dr. Shlivko can evaluate whether prism correction is right for your specific situation.
When Might Your Doctor Prescribe Prism Lenses?
Your eyes need to aim at the same target and work in sync, a process called binocular vision. When something interferes with that coordination, double vision can result. The American Academy of Ophthalmology notes that prism lenses help with several conditions where eye alignment is imperfect.
Common reasons your optometrist might recommend prisms include eye muscle weakness, nerve damage affecting eye movement, strabismus (crossed or turned eyes), or issues from stroke or neurological conditions. Some people also develop double vision after certain surgeries or injuries. Your doctor will evaluate your specific eye alignment during your exam and determine if prism correction can help. The strength and direction of the prism are customized to your exact needs, so every prescription is different.
Prisms are also used to help manage symptoms like headaches, dizziness, or eye strain that result from your eyes working too hard to align on their own. If you're experiencing double vision on Avenue U or anywhere in Brooklyn, don't wait. The sooner you get evaluated, the sooner you can start feeling better.
How Prism Strength Is Measured and Prescribed
Prism power is measured in units called prism diopters. Your prescription might include something like "2 prism diopters base in" or "1.5 prism diopters base out," which tells us how much the light needs to be bent and in which direction. Higher numbers mean stronger correction.
During your exam, your doctor uses specialized tests to measure exactly how misaligned your eyes are and in which direction. The prescription is written with both the strength, in prism diopters, and the base direction (base in, base out, base up or base down), so your lenses bend light in the right direction for your eyes (American Academy of Ophthalmology).
Prism lenses can be made in any prescription strength, whether you need correction for nearsightedness, farsightedness, astigmatism, or reading. They can also be combined with other lens features. At Vision Palace Optical, we work with you to make sure your prism prescription is accurate and comfortable, because even small adjustments in prism strength can make a big difference in how you see.
Prism Contact Lenses: What They Are, Their Limits and Who They Suit
A prism contact lens is a contact lens made thicker at one edge so that it shifts the image the way a prism in eyeglasses does. Many people who search for prism contact lenses are hoping to stop wearing their prism glasses, so it helps to know what contacts can and cannot do.
Why prism contact lenses are rare
A contact lens sits on the eye and moves with it, so a prism built into the lens has to stay pointing the right way. In most cases that isn't possible: an American Academy of Ophthalmology ophthalmologist answering this question notes that in nearly all situations prism cannot be built into contact lenses, and only a very small amount of vertical misalignment can be addressed with contacts (American Academy of Ophthalmology).
The direction is limited too. Soft lenses that carry prism are made thicker at the bottom, so the prism can only be base down. The Academy's EyeWiki reports correction of up to four prism diopters base down for vertical double vision with custom prism-ballast soft contact lenses. It also reports that rotationally stable scleral lenses, which are larger lenses that rest on the white of the eye, have been shown to carry up to four prism diopters in any direction, including horizontally (AAO EyeWiki: Contact Lenses). These are specialty lenses, not something you can order off the shelf.
Prism ballast is not prism correction
You may see "prism ballast" on a box of toric lenses for astigmatism. Toric lenses have to stay at a set angle on the eye, and a prism-ballast design is one way to stop them rotating: the lens is thinner at the top and thicker at the bottom (AAO EyeWiki: Contact Lenses). That prism keeps the lens steady. It is not written for your eye alignment and does not treat double vision.
Who prism contact lenses may suit
Prism contacts may be an option for someone whose double vision comes from a small vertical misalignment, one image sitting slightly above the other, and who has a strong reason to wear contacts. For horizontal misalignment or larger amounts of prism, glasses are usually the practical choice. When someone needs more prism than contacts can carry and wants to wear contacts again, the AAO answer notes that strabismus surgery is in most cases the only option (American Academy of Ophthalmology).
Prism eyeglasses are also easier to change. If your prescription needs fine-tuning, new lenses can be made with a different prism strength or direction. During your eye exam at Vision Palace Optical, Dr. Sheyko or Dr. Shlivko can measure how your eyes are misaligned and talk you through whether glasses, contacts or a referral makes the most sense for your condition, eye health and lifestyle.
What to Expect When You Start Wearing Prism Lenses
When you first put on prism lenses, your vision might feel strange for a few days. Your brain is learning to process the corrected image alignment, and that adjustment period is completely normal. Most people adapt within a week or so, though it varies.
Some people notice immediate relief from double vision, while others notice that headaches or eye strain gradually improve over time as their eyes stop working so hard to compensate. Wear your prism lenses as prescribed, and don't switch back and forth between them and non-prism lenses during the adjustment period, as that can slow down adaptation.
If you're not adjusting well after a week or two, come back in and let us know. Your prescription might need a small adjustment, or there might be another reason your eyes aren't adapting as expected. This is why follow-up communication with your doctor is important.
Frequently Asked Questions
What causes double vision, and is it always treatable with prisms?
Double vision can come from eye muscle weakness, nerve damage, strabismus, or neurological conditions. Not every case of double vision is best treated with prisms, though. Your doctor will evaluate the cause and recommend the most appropriate treatment, which might be prisms, vision therapy, surgery, or something else entirely.
Will prism lenses permanently fix my double vision?
Prism lenses manage the symptoms of double vision by helping your eyes align properly while you're wearing them. They don't cure the underlying condition, but they do allow you to see clearly without the discomfort of diplopia. Your doctor will discuss whether your condition is temporary or long-term and what ongoing care might look like.
Can I get prism contact lenses instead of prism glasses?
Sometimes, but rarely. In nearly all situations prism cannot be built into contact lenses; a very small amount of vertical misalignment can be addressed with them, according to the American Academy of Ophthalmology. Custom soft lenses can carry prism only base down, and specialty scleral lenses have been shown to carry a small amount in any direction. Your optometrist can tell you whether your prescription is within that range.
How much do prism lenses cost?
Pricing for prism lenses depends on the lens material, any additional lens coatings or treatments, and your frame choice. Coverage varies by plan. Call us or book through Zocdoc to verify your insurance benefits before your visit.
How long does it take to adjust to prism lenses?
Most people adapt to prism lenses within a week or two. Your brain is learning to process the realigned image, and that takes a little time. If you're still experiencing discomfort after two weeks, let your doctor know, as your prescription might need adjustment.
References
- American Academy of Ophthalmology. What Is Prism Correction in Eyeglasses?
- American Academy of Ophthalmology. Can I have prism correction built into my contact lenses? (Aaron M Miller, MD, 2019)
- AAO EyeWiki. Contact Lenses.
If you're experiencing double vision or think you might benefit from prism lenses, don't wait. Book your eye exam at Vision Palace Optical. Book through Zocdoc, get in touch, or call us at (718) 998-8400. We're at 1723 Avenue U in Brooklyn, open Monday through Saturday. Dr. Sheyko and Dr. Shlivko are here to help you see clearly again.