Last updated on June 7th, 2017 at 07:07 pm
Eye tests for contact lenses include unique tests that normally are not carried out in regular eye examinations for eyeglasses.
So if you have an interest in contacts — or you already use them and want to have your contact lens prescription updated — make certain you state so when you schedule your appointment for an eye exam. This will ensure your test consists of extra time for your eye doctor or ophthalmologist to perform extra tests required for a correct contact lens fitting or prescription upgrade.
Eye Exams For Contact Lenses
Also, be aware that it’s typically easier and affordable to have your general eye examination and your contact lens examination performed by the very same eye care professional (ECP). If you have these examinations carried out by various ECPs at different locations, the professional performing your contact lens test may want to duplicate certain tests already performed during your basic eye exam, and this may involve additional fees.
This is due to the fact that the second ECP is accountable for the health of your eyes during contact lens wear, and she or he may wish to verify the health of your eyes and the precision of your eyeglasses prescription to have the best data possible to carry out a safe, effective contact lens fitting.
Replicate testing is especially likely if the ECP performing your contact lens examination does not have access to the record of your general eye test carried out by the first doctor.
What To Expect During A Contact Lens Fitting
During your extensive eye examination, your visual acuity will be checked utilizing an eye chart, and a variety of tests will be performed to determine your eye health and whether prescription glasses is required to fix refractive mistakes.
After this screening has been finished, your optometrist will collect extra information so you can be fitted with contact lenses.
You might be asked general questions about your lifestyle and preferences relating to contact lenses, such as whether you may wish to alter your eye color with color contact lenses or if you’re interested in options such as day-to-day disposables or over night wear.
Your eye doctor may also discuss the alternative of stiff gas permeable (RGP or GP) contact lenses, which frequently supply sharper vision than soft lenses.
Your eye doctor likewise might ask how you wish to fix vision issues related to aging. A long time after age 40, you will develop a condition called presbyopia that reduces your capability to read fine print and concentrate on near things.
To fix presbyopia, your eye doctor may provide you the choice of multifocal or bifocal contact lenses. Another option is monovision, which is a special contact lens fitting method where one eye is corrected for range vision and the other eye is fixed for near vision.
Contact Lens Measurements
Just as one shoe size does not fit all, one contact lens size doesn’t fit all.
If the curvature of a contact lens is too flat or too steep for your eye’s shape, you might experience pain or even damage to your eye. Other parts of a contact lens fitting consist of:
Cornea measurements. An instrument called a keratometer will be used to measure the curvature of your eye’s clear front surface (cornea).
The keratometer examines light reflections from your cornea and determines the curvature of your eye’s surface. These measurements assist your optometrist pick the correct curve and size for your contact lenses.
Due to the fact that the keratometer determines just a little, minimal section of the cornea, additional computerized measurements of your cornea may be performed utilizing an automated instrument called a corneal topographer. Corneal topography supplies very precise details about surface area attributes of the entire cornea. It does this by determining how the device’s light shows off of your eye.
With one version of a corneal topographer, you are seated facing the device with your forehead resting against a curved brace. Circular patterns of light then are beamed into your eye for analysis. A computer creates and prints out the resulting surface “map” of your eye, with various shapes represented by varying colors.
In some cases, corneal topography measurements are integrated with wavefront measurements that can provide even more particular details about how well the eye focuses light, identifying higher-order aberrations. These combined measurements can assist your optometrist identify the type of contact lenses that will provide you the sharpest vision possible.
If your eye’s surface is discovered to be rather irregular since of astigmatism, you may require an unique design of lens referred to as a toric contact lens that is formed to offset distortions of your eye to supply sharper vision.
At one time, just stiff contact lenses could correct for astigmatism. But there are now lots of brand names of soft toric lenses. Toric lenses likewise are readily available in non reusable, multifocal, extended wear, and colored versions.
Pupil and iris measurements. The size of your eye’s pupil might also be measured. In an easy method, a card or ruler showing various pupil sizes is held beside your eye to figure out the best match.
Automated instruments that measure pupil size also exist. These instruments are capable of exceptionally precise measurements, and some at the same time measure the horizontal and vertical size of your pupil.
Comparable technologies likewise may be used to measure the diameter of the colored part of your eye (iris). Pupil and iris measurements help your ECP select contact lenses that are of a correct size to fit well and look best on your eyes.
Tear film assessment. Contact lens fittings might likewise consist of a tear movie examination.
Your body’s ability to produce tears might be examined through use of small strip of paper inserted below your lower eyelid. You close your eyes for about five minutes, and then the paper is eliminated. The length of the paper dampened by your tears is measured to evaluate your tear production and determine if you have dry eyes.
Another technique of discovering dry eye involves including fluorescein dye to the tear layer on your eye through eye drops or a moistened paper strip containing the dye, and then assessing the length of time it takes for your tears to vaporize.
If you have a severe dry eye condition, you might need to avoid or cease contact lens wear. However in cases of contact lens pain due to moderate dryness, special contact lenses for dry eyes might allow you to use contacts securely and easily.
Assessment of your eye’s surface and contact lens fit. The health of your cornea will be evaluated using a biomicroscope (likewise called a slit light). This lighted instrument offers an extremely amplified view of the cornea and other tissues to allow your eye doctor to examine the health of the front of your eyes and detect any modifications caused by contact lens wear.
The biomicroscope also is used to assess the fit of a trial contact lens, due to the fact that it enables your doctor to observe the alignment and movement of the lens as it rests on the surface area of your eye.
Usually a preliminary contact lens fitting requires follow-up check outs to make sure the lenses are resting effectively on your eyes and supplying the best vision for you.
When trial lenses are used, you typically will have to use them a few minutes so that preliminary tearing of the eye stops and the lenses stabilize. Your optometrist can then make an appropriate examination of how the lenses fit without the presence of excess moisture triggered by tearing.
In follow-up sees, your eye doctor may stain your eye with fluorescein to look for flaws and ensure your contact lenses are not harming your eye’s surface. You typically will need to eliminate your contact lenses before this test is carried out.
After discovering contact lenses that fit correctly, are comfortable for you, and provide good vision, your optometrist can write your contact lens prescription. This prescription will designate contact lens power, a shape matching the curvature of your eye (base curve), and size.
Normally, it takes two or 3 follow-up check outs to finish an uncomplicated contact lens fitting. After that, you should have yearly contact lens examinations so your eye doctor can monitor the health of your eyes. In some cases, you might need more frequent tests or extra follow-up visits.
Keep in mind that if you use contact lenses, your annual eye exams generally will cost more than a routine test for somebody who doesn’t wear contacts, due to the extra contact lens-related tests that are included.