Conductive Keratoplasty (CK) is an innovative refractive surgical technique designed to correct certain vision problems by reshaping the cornea without involving lasers or cutting tissue.

Utilizing radiofrequency energy, CK offers an alternative approach for treating low to moderate hyperopia (farsightedness) and presbyopia (age-related difficulty focusing on close objects).

The Principles Behind Conductive Keratoplasty

The foundation of CK lies in the biomechanical response of corneal collagen to controlled heating. When collagen fibrils within the corneal stroma are exposed to temperatures around 55 to 65 degrees Celsius, they undergo shrinkage through dehydration but maintain structural integrity upon cooling.

CK uses a precisely controlled radiofrequency current delivered via a fine probe inserted into the peripheral corneal stroma. The resistance of the tissue to this energy generates localized heat, causing collagen contraction.

As collagen fibers in the mid-peripheral cornea contract, this induces a tightening or cinching effect around the cornea's outer edge. The result is a steepening of the central cornea's curvature, increasing its refractive power. This change shifts the eye's focal point forward, improving near vision, particularly benefiting patients with mild to moderate farsightedness or early presbyopia.

Procedure Details and Technique

Conductive keratoplasty is performed in a clinical setting, usually under topical anesthesia via numbing eye drops. The patient's eye is held open gently using a speculum, and the corneal surface is marked to guide treatment placement.

Treatment is delivered via a small hand-held probe—much thinner than a thread—that applies radiofrequency energy to designated spots arranged in a circular pattern, typically on an 8 mm or 7 mm radius from the corneal center.

The number of treatment spots varies but often includes 8, 16, or up to 32 applications around the peripheral cornea, as determined by the patient's individual prescription and treatment plan. The energy delivered is finely calibrated to ensure uniform collagen shrinkage without causing necrosis or damage. The entire process takes approximately 10 minutes and does not require incisions or tissue removal.

Candidate Selection and Suitability

Ideal candidates for CK are those over the age of 40 with stable low to moderate hyperopia (typically +0.75 to +3.00 diopters) or early presbyopia who desire improved near vision. Suitability depends on corneal thickness, biomechanical properties, and absence of conditions such as keratoconus or severe dry eye, which could increase surgical risks.

Patients must also have relatively stable refraction for at least one year before surgery. It is important for patients to understand that CK mainly enhances near vision, and slight compromises in distance vision may occur, necessitating occasional use of glasses. Unlike laser surgeries, CK does not permanently remove corneal tissue but induces changes through controlled collagen shrinkage.

Patients must also have relatively stable refraction for at least one year before surgery. It is important for patients to understand that CK mainly enhances near vision, and slight compromises in distance vision may occur, necessitating occasional use of glasses. Unlike laser surgeries, CK does not permanently remove corneal tissue but induces changes through controlled collagen shrinkage.

Advantages and Expected Outcomes

CK offers several benefits including its minimally invasive nature, rapid recovery, and reduced discomfort compared to laser refractive surgeries. Because it does not involve cutting, risks of flap-related complications seen in LASIK are avoided. The procedure remains outpatient, with most patients resuming normal activities quickly.

Visual improvement in near vision is often noticeable within a few days, though optimal results develop over weeks. Studies indicate CK improves near vision accuracy and reduces dependence on reading glasses while preserving distance vision in most patients. The accuracy and predictability have improved with advances in technology and nomogram-based treatment planning.

Limitations and Considerations

A notable limitation of CK is the duration of effect, as some regression of corneal steepening may occur over time, particularly beyond two years. Repeat treatments can be performed to maintain desired outcomes. The procedure is less effective for patients with high hyperopia or advanced presbyopia.

Furthermore, CK does not address other refractive errors like significant astigmatism or nearsightedness.

Dr. Maloney, a principal investigator in FDA clinical trials including CK, emphasizes the advantages of CK over other vision correction methods: "CK seems to preserve the quality of vision better than hyperopic LASIK," says Dr. Maloney. "We have patients after hyperopic LASIK who have 20/20 vision, but who are very unhappy with their quality of vision; they describe it as filmy or hazy, and with our present technology, there's nothing we can do about that."

Conductive keratoplasty is a unique refractive procedure leveraging radiofrequency energy to reshape the cornea by collagen shrinkage. Its applicability in correcting low to moderate hyperopia and presbyopia offers an alternative for patients seeking improved near vision without tissue removal or lasers. As ongoing research refines this technology, conductive keratoplasty remains a valuable option within the spectrum of vision correction surgeries.