Conductive Keratoplasty
Author: Sherman Winston Reeves, M.D., M.P.H.

Nearvision Conductive Keratoplasty (CK)

Definition: Nearvision conductive keratoplasty (CK) is a refractive surgery procedure which uses radiofrequency energy to reshape the cornea and correct presbyopia.

How Does NearVision CK Work?

The cornea plays an important role in bending the light properly as it enters the eye. Conductive keratoplasty works by increasing the curvature of the cornea in a uniform fashion and adding more light bending power to the eye’s optical system. To accomplish this, a small probe is placed in the edge of the cornea which applies radiofrequency energy to the corneal substance. This energy causes the cornea immediately around the probe to shrink slightly. The probe is then applied in a ring pattern around the cornea, like marking clock hours on a clock dial. This ring pattern application of local shrinking causes the center of the cornea to assume a more steeply curved shape, which bends (refracts) light more strongly.

By increasing the curvature of the cornea in just one of a person’s eyes, presbyopia can be treated. The more steeply curved a cornea is, the more bending power of light it has. If incoming light is bent too much, it comes to a focus at a point in front of the retina in the middle of the vitreous of the eye. In this situation, an eye becomes slightly myopic(nearsighted). CK can be used to induce a mild amount of myopia in one of a person’s eyes, moving the eye’s natural focal point to reading distance and creating a monovision effect, helping to reduce presbyopia symptoms.

Who are candidates for Nearvision CK?

Nearvison CK can be used to treat patients who are suffering from presbyopia .

Candidates for presbyopia treatment with Nearvision CK should be:

• Suffering from the symptoms of presbyopia, which usually begin to occur between the ages of 45 to 55.
• Have very good distance vision without glasses or contact lens correction. As CK makes one eye nearsighted in order to treat presbyopia with a monovision effect, the other eye needs good distance vision for a person to see clearly in all situations.

These conditions may prevent you from undergoing Nearvision CK or other refractive surgeries. You should alert your eye surgeon if you have one or more of these conditions so that he or she can help you make the best choice about undergoing refractive surgery:

Examination prior to Nearvision CK:

Before you arrive at the doctors office:

If you are a contact lens wearer, you should stop wearing you lens for at least 2 weeks if you wear soft contacts or 1 month if you wear hard contacts. Contact lenses can cause mild warping of the corneal shape, which can interfere with the preoperative measurements of the eye and calculations for Nearvision CK surgery.

Tests you may have at the doctor’s office:
The evaluation for Nearvision CK surgery typically includes a complete eye exam of the front and back of the eye, plus several additional tests. Your visual acuity with and without glasses will be tested, as well as a refraction to determine if your current vision differs markedly from the vision corrected in your current glasses. If they do differ markedly, you may need to return for another visit several weeks later for a repeat refraction to insure that your prescription is not changing. If you are presbyopic, your near reading ability will also be tested. Your eyes may also be dilated to be examined completely. Your doctor will perform a slit lamp examination to examine the eye and the lens. A retinal exam may also be performed during the dilated examination. A second refraction may be performed after your eyes have been dilated. Lastly, measurements of the shape and curvature of your cornea will be taken to help your doctor plan the CK treatment.

Is perfect reading vision guaranteed with Nearvision CK?

Nearvision CK surgery is an extremely advanced technology for surgical vision correction. The eye can be measured very precisely and your surgeon will be highly skilled in performing the procedure. As such, the vast majority of people undergoing Nearvision CK surgery are very happy with their post-procedure vision and achieve greatly increased near vision function versus what they had before. In fact, a person’s happiness with their vision after the procedure is a far more important measure of success than the somewhat arbitrary measurements of near and reading vision done in the controlled setting of a doctor’s office.

However, several factors may lead to a person having vision after the surgery which still requires additional help from reading glasses for near viewing activities. Though very precise measurements and surgical technique are used for Nearvision CK surgery, the individual healing response of each patient may result in some variability of the final refractive outcome. Generally, though, this variability is very small and people are highly satisfied with the surgery. Additional Nearvision CK treatment may sometimes be used after the initial Nearvision CK procedure to “touch up” any residual refractive error. Occasionally, though, glasses or contacts will still be needed for some viewing situations after Nearvision CK surgery.

What are the Risks of Nearvision CK surgery?

Though the risks of Nearvision CK surgery are small, vision can be lost in several ways:

Infection: Since cuts are made on the eye, it is possible that bacteria could gain access to the corneal tissue and start an infection. Scarring from such an infection could lead to vision loss. This is very uncommon as powerful antibiotics are used after Nearvision CK to prevent infection.

Induced astigmatism: Nearvision CK can occasionally cause astigmatism in an eye where it was not initially present. Typically, this astigmatism causes little effect on the vision. Rarely, the vision may be affected by astigmatism from the Nearvision CK procedure, which could require glasses, contact lenses or additional refractive surgery to correct.

Regression of effect: In some patients, the effect of Nearvision CK may decrease with time. This regression does not cause loss of vision, as it can still be corrected with glasses or contact lenses, but can be frustrating to both the patient and doctor.

What will I experience during the CK procedure?

On the morning of your procedure, your surgeon will ask you not to wear any makeup, which may contaminate the eye during surgery. At the surgery center, you may be given a Valium pill to help you relax and feel more comfortable during the procedure. Nearvision CK is, in general, a very simple procedure to undergo, so no Valium may even be required. The Nearvision CK procedure itself usually takes about 20 minutes or less to perform. Anesthetic eye drops are all that is required to numb the eye.

During Nearvision CK surgery, an eyelid speculum is used to hold the lids open and help conduct the radio frequency energy. During the surgery, you may see bright and multi-colored lights as well as blurry shapes moving in front of the eye. Then the cornea is marked with an inked marking instrument to help guide the placement of the treatment spots. Next, the tiny probe is placed into the cornea and the radiofrequency energy applied to cause focal shrinkage of the corneal tissue. You will have no sensation that this is occurring, as the eye will be numb from the anesthetic drops. The wounds in Nearvision CK surgery are very small, and usually heal within a day or less. A bandage contact lens may be placed on the eye for the first 24 hours to help the wounds heal more comfortably. Last, antibiotic and steroid eye drops are placed in the eye. A plastic shield may be placed on your eye after the surgery to help remind you not to rub the eye for the first night.

After the procedure is done, you will rest briefly in the recovery area, after which someone can drive you home. Especially if you had Valium before the surgery, driving yourself to and from the surgery center will not be allowed. Your eye may start to burn and feel irritated about an hour after the surgery as the numbing medicine wears off. Artificial tears can help make the eye feel more comfortable. Your surgeon may also have you start antibiotic and ibuprofen drops on the evening after your surgery as well.

After your surgery, you should not rub or press on the eye for at least 1 to 2 weeks. Gentle cleaning around the eye with a damp wash cloth or cotton ball is fine, though. Avoid getting soapy or dirty water in the eye, and do not swim or use hot tubs for at least 2 weeks after the surgery.

Your doctor will usually see you the next day, at which point the eye is usually feeling comfortable. You will continue using eye drops for several weeks after the surgery, and then see your doctor again in 1 to 3 weeks for a vision check. If all is well, as it typically is, your doctor will usually see you again in 6 months to a year for another vision check.