Fitting Toric contacts (for astigmatism) may be more time consuming than fitting spherical lenses. This is because toric contact lenses are different than standard spherical contact lenses.
Spherical lenses: either thin in the centre (minus power for nearsighted people) or thick in the centre for farsighted people (plus power). As you go around the clock of the lens, thickness is uniform.
Toric lenses: thickness varies throughout the lens. This allows astigmatism correction to be added to the prescription.
Toric contacts are made to made to correct for astigmatism in a prescription (click here for more on what astigmatism is). Because of these differences, they are more complicated to fit than other lenses. In a spherical contact lens, there are three parts to the contact lens prescription: (1) the Brand (2) the curvature, and (3) the power. In a Toric lens, there are an additional two parts that need to be accounted for: the cylinder (cyl) and the axis.
Because of the astigmatism, a Toric lens must sit in one place on the eye, and cannot rotate. If it does, your vision will blur. With glasses, the lenses are connected to the frame, which is hooked to your ears, and always in one position in relation to your eyes. Contact lenses, on the other hand, don't have arms, or temples, to stabilize them. They are oriented by the way they touch your eyelids, or by a weighted part of the lens (or a combination). When fitting toric contacts, the fitter can't tell what will happen to the contact lens, in relation to the eyelids that touch it. Because the physiology of each person's eye is different, several things may happen when the contact lens is placed on the eye:
The way the lens fits must be assessed by the contact lens fitter, and each problem addressed individually. Toric lenses also take longer to settle than standard lenses, and after being worn for several hours or days may not be the same as when you were in the office.
If you have never worn contacts before, you may need to wait for trial contact lenses to be ordered if you need a Toric lens. Once they come in, if you are lucky, the first pair you try will work for you. However, it is not uncommon to need to try different lenses; the higher the astigmatism, the harder it is to get accurate vision with soft lenses.
Even if you have worn contact lenses before, if there is a change in your prescription and/or if you are trying a different brand, you should try the contacts first to ensure the vision is good for you. Sometimes there is a small axis (rotation) change of 5 degrees which may or may not require a change in the contacts you order.
So do not be surprised if you have to wait to get contacts before fitting toric contacts; and be prepared to trial a pair or two (or more) before you finalize the fitting.
If you have never worn Toric contact lenses before, there are some points you should be aware of.
1. Weighted Lens - Most Toric lenses are weighted so that your vision is stabilized. When placing this type of lens on your eye, it becomes a bit of a challenge because the weight can tip and make the lens unbalanced while attempting to insert.
TIP: instead of moving the lens across towards your eye, try moving the lens in an upward direction towards your eye. (Drawings)
2. Acuvue Oasys or Advance (different design) - Tis lens is designed differently from other Toric contacts lenses. Instead of a weighted edge to keep the lens from rotating on the eye, these lenses have differing edge thicknesses. The edges touching the eyelids are thinner, and the other edges are thicker. You may notice that when these contacts are placed on the finger, they tend to roll up. Tis is normal for Acuvue Advance and Oaysy for Astigmatism, so don't think there's anything wrong with them.
3. Most Toric contact lenses have "scribe" marks, which are little lines on the contact lens that indicate to the eye car practitioner that the lens nips oriented in the correct position. You can use these markings to your advantage as well. If you can see them (it's harder if you are farsighted or presbyopic), the little lines go toward the lower lid with most lenses. With Acuvue Advance and Oasys for Astigmatism, there are two lines: one at the top (upper lid) and one at the bottom (lower lid). It doesn't matter which one goes top or bottom.
4. Toric contact lenses are usually easier to tell if they are inside out, because the shape is more obviously incorrect to place on the eye. (See below.)
Toric contact lenses are a bit thicker than other contact lenses. Tis makes them a little more durable than typical contacts. You still do need to be careful with them though, because they'd ill have one edge that is thinner and more prone to tearing.
Otherwise, care for your Toric contact lenses the same way you would other contacts.
Take note of whether they are monthly replacement, two week replacement, or daily disposable lenses.
There are a number of benefits to Toric contact lenses:
While there are some great benefits to wearing Toric contact lenses, particularly the better vision available, there are some drawbacks.
Fitting Toric contacts can be quick and easy, or it can be frustrating and require a lot of patience. Sometimes it can be attributed to the experience of the fitter, and sometimes the lenses available just don't fit the eye or the prescription well. However, it can be well worth the time it takes to fine tune your vision, if you would like to be able to bet away from glasses and still be able to see well.
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