20th, January 2020 | Oh Jinna
Toric Lens or GP Lens: Which Lens is Best for Astigmatism
Way back when, glasses were the only option to correct and manage astigmatism. Until the dawn of the new age of technology, a fresh kind of alternative has found its way to the medical market.
Even with the breakthrough of lenses, some people still have a harbored misconception of lenses. The idea that — only glasses are suitable for astigmats. However, that is a myth.
Astigmatism is one of the most common eye conditions affecting roughly 30% of the differing population. The number has significantly risen to 14% and that is only from the year 2014 alone.
From as early as 15 years old to 60, astigmatism can develop with the consideration of other factors as well.
In this article, two of the kinds of lenses to correct astigmatism will be introduced and then discussed. In the latter part, you will discover which lens is best for astigmatism.
Let’s first start off with the first kind: toric lens.
What are Toric Lens
The term “toric contact lenses ” has now been associated with soft contact lenses that are designed to correct astigmatism.
Toric lenses are made with either a conventional hydrogel material or a highly breathable silicone hydrogel material.
These lenses have a very distinct form and they are purposely shaped like a torus. If you’re wondering what a torus looks like, just picture a fluffy donut.
Unlike the normal lenses that have a spherical surface following the standard, toric is structured like a sliced donut.
According to an article published by the CooperVision, the shape of toric contact lenses “creates different refractive, or focusing, powers on the vertical and horizontal orientations.” and depending on the movement of the lens around your eyes, the refractive strength increases or decreases gradually.
How Toric Lens Correct Astigmatism
Toric lenses correct only myopia or hyperopia and this is how toric lens manage astigmatism:
Toric lenses have different powers in different meridians of the lens to correct the varying amount of nearsightedness or farsightedness in different meridians of the eye.
Their design feature enables the lens to rotate to the proper orientation on the cornea so the power meridians of the lens align with the appropriate meridians of the eye for clear vision.
You might have to need more than one pair of toric lenses to satiate your very own needs because every eye with astigmatism is different and might require the fit that meets with your condition.
Fitting for Toric Contact Lenses
The features that the manufacturers have integrated in toric lenses are thin-thick zones, lens truncation (where the bottom of the lens is slightly cut off), and ballasting (where the lens is a little thicker or heavier).
With these features, they keep the lenses secure and adhere to the eye shape of the wearer.
Toric contact lenses have a middle axis. Sort of like the Earth’s equator which aids in keeping your line of vision clear.
Wearing toric lenses that don’t fit well will cause you the visual clarity and that you expected.
Keep in mind that toric lenses have a very complex design and the fitting of these lenses requires an impeccable knack than fitting regular soft lenses.
With these predicated, getting fitted with toric contact lenses typically costs more than a regular contact lens exam.
The cost of replacement toric contact lenses is higher than the cost of regular (spherical) soft contacts.
The difference in cost will depend on the lens design, lens material, and where they are bought.
What are GP Lens?
GP contact lenses which stand for gas permeable or also called RGP (rigid gas permeable) are another popular alternative for controlling and correcting astigmatism.
GP contact lenses also follow a toric design however 99% of the time, GPs can correct astigmatism without a toric design because gas permeable lenses are rigid and can hold their spherical shape on the eye without keeping the irregular shape of the cornea of an eye.
How GPs Correct Astigmatism
When fitting with GPs, your eye topography is mapped which in turn enables the back surface of the lens to better align with the cornea. With these reasons, the exact shape of your cornea will be measured as exactly as possible.
The outcome of the prescribed lenses will have the right curvature, size, and corrective power which will eventually be effective in controlling astigmatism.
If in full effect, the uniform front surface of GPs replaces the misshapen cornea as the primary refracting surface of the eye, and thus correcting astigmatism without the need to control the rotation of lens with a toric design.
Benefits of GP or RGP Contact Lenses
Because of the strong material and the ability to diffuse oxygen, GP lenses offer a number of advantages and here are some of the benefits of using GPs:
Health and Hygiene
GPs don’t contain water, unlike soft lenses, which prevents them from likely attracting and producing bacteria that can contract eye infections.
Further the chance of protein deposits build-up on the lens is less to none which keeps them cleaner and healthier.
GP contact lenses clean and disinfect easily, don’t dehydrate, are easier to handle, and last longer than soft lenses.
Comfort
GP contact lenses are custom made for each patient based on the eye’s individual curvature, size, corneal shape.
Their ability to transmit oxygen reduces eye problems such as dry eyes caused by reduced oxygen that are common in many brands of soft lenses or hard (non-GP) lenses.
GP lenses have a smaller diameter than soft contacts, meaning that they cover less of the surface of your eye.
While this may take some time getting used to initially, ultimately many find that they are just as more comfortable than soft contacts.
Vision
GPs have a smooth surface and can maintain their shape due to the rigid material.
They can even hold their place and can go along the frequent movement of the eyes which provides a sharp and stable vision.
Further they do not dehydrate, which is often a cause for reduced vision with other lenses.
Cost
GPs are much more cost effective because they last longer unlike the soft lenses disposable lenses that require a constant supply.
However, you might still need to invest more than necessary because they are made to order and they will take up to a week to manufacture if you do need a replacement pair.
Which Lens is Best for Astigmatism
Toric or GPs for Astigmatism
GP lenses are ideal for individuals with astigmatism that may have been told that they cannot wear soft contacts.
Because of the rigid nature of the lens, they hold their shape on the eye allowing for more clear and stable vision correction.
One of the leading causes of eye infection for contact lens wearers is bacteria formation. GPs don’t contain water like soft lenses do.
For this particular reason, they counter any deposits and are less likely to accumulate bacteria.
On top of that, since GP contacts retain their shape better, they provide crisper vision than soft contact lenses.
As for toric lenses, they are beneficial to the many who cannot opt for rigid gas permeable. They are made out of soft material making their longevity very limited. Their durability is typically short-lived and you might have to replace them as often as possible.
Although both contacts are comprised of very expensive materials, it is only expected that they are going to cost more than the regular lenses.
They surely will break your bank but it would make a difference if you utilize the best lens which is suited just for you.
At the end of the day, it is still entirely up to your eye care practitioner and the prescribed lens that they will give you.
References:
https://www.allaboutvision.com/contacts/torics.htm
https://coopervision.com/about-contacts/toric-contact-lenses
https://www.contactlenses.org/whatare.htm
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