Conductive Keratoplasty Hyperopia and Presbyopia Treatment & Management

Updated: Mar 15, 2016
  • Author: Manolette R Roque, MD, MBA, FPAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Treatment

Medical Therapy

Medical therapy is limited to broad-spectrum topical antibiotics and corticosteroids for uncomplicated cases (see Postoperative details).

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Surgical Therapy

See Intraoperative details for the surgical procedure.

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Preoperative Details

The procedure for CK can be performed with a local (topical) anesthetic in the form of eye drops to numb the eye. Patients who are nervous and/or have a high level of anxiety may be given a mild sedative to assist them in relaxing for the procedure.

The operative field is prepared, and the patient is prepared in the usual sterile fashion for ophthalmic surgery. A lid speculum, as shown below, is used for globe exposure.

Hyperopia, conductive keratoplasty. Speculums. Pub Hyperopia, conductive keratoplasty. Speculums. Published with permission from Refractec.

This procedure may be performed inside the clinic.

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Intraoperative Details

After appropriately preparing the patient, a lid speculum is used to hold open the eye during the CK procedure; it also serves as a return path for the radiofrequency energy applied via the instrument. CK is performed using a pen-shaped instrument to apply controlled radiofrequency energy in a ring pattern on the cornea. In performing CK, the conductive tip should be placed perpendicularly to the corneal surface prior to activation. This placement of the conductive tip ensures appropriate application of the conduction marks. The procedure is considered painless and typically requires only a few minutes (approximately 5 min) to perform. See the images below.

ViewPoint conductive keratoplasty device. Publishe ViewPoint conductive keratoplasty device. Published with permission from Refractec.
Hyperopia, conductive keratoplasty. Suture. Publis Hyperopia, conductive keratoplasty. Suture. Published with permission from Refractec.
Hyperopia, conductive keratoplasty. Corneal markin Hyperopia, conductive keratoplasty. Corneal markings. Published with permission from Refractec.
Hyperopia, conductive keratoplasty. ViewPoint with Hyperopia, conductive keratoplasty. ViewPoint with radiation. Published with permission from Refractec.
Hyperopia, conductive keratoplasty. Change in corn Hyperopia, conductive keratoplasty. Change in corneal curvature. Published with permission from Refractec.

LightTouch technique

LightTouch is a corneal compression technique in which surgeons should apply minimal pressure to the cornea. The application of the tip is similar to the initial procedure identified above, except that after the tip is completely implanted into the cornea, it is retracted slightly until there is minimal to no indentation of the cornea, followed by application of the radiofrequency energy. See the images below.

NearVision conductive keratoplasty with LightTouch NearVision conductive keratoplasty with LightTouch technique.
Conductive keratoplasty conventional pressure tech Conductive keratoplasty conventional pressure technique.
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Postoperative Details

Following the procedure, the lid speculum is removed. Postoperatively, antibiotic-corticosteroid combination drops and/or ointment are used. Antibiotic-corticosteroid combination drops are used 4 times daily for 1 week. The eye may be covered overnight with a shield.

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Follow-up

Certain precautions should be taken following the CK procedure and are similar to those that are required with any other type of vision procedure where the cornea is altered.

Patients should take the following precautions for at least 1 week after surgery:

  • Avoid getting contaminated water (eg, fountains, swimming pools, spas, lakes, ocean, rivers) in the eyes.

  • Keep the eyes closed while showering or taking baths to avoid getting soap and dirty water into them.

  • When exercising, keep sweat out of the eyes.

  • For females, avoid applying eye makeup.

Patients should avoid vigorously rubbing the eyes for 2 weeks after the surgical procedure.

Patients are seen postoperatively on day 1; week 1; and months 1, 3, 6, and 12. Vision begins to improve within a week's time. The surgeon should monitor patients for postoperative complications; an observation timeline is outlined in Complications.

For patient education resources, see the Eye and Vision Center, as well as Vision Correction Surgery and Contact Lenses.

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Complications

See the list below:

  • Preservation of best spectacle corrected visual acuity (BSCVA) [32, 33, 34]

    • Loss of greater than 2 lines BSCVA in less than 5% of eyes

    • Decrease from 20/20 preoperative to worse than 20/40 postoperative in less than 1% of eyes

  • Induced cylinder [35]

    • Induced cylinder greater than 2.00 D in 5% of eyes (< 1% of eyes per draft ANSI guidance)

    • Induced cylinder greater than 1.00 D reported in labeling for all comparable products for hyperopia treatment

    • Induced cylinder greater than or equal to 1.00 D reported at request of FDA

    • Effect of induced cylinder and axis shift on UCVA eyes treated with current nomogram

    • Approximately 1 line impact on mean UCVA at 12 months in the following:

      • Eyes with greater than 1.00 D and greater than or equal to 1.00 D induced cylinder

      • Eyes with greater than 1.00 D and greater than or equal to 1.00 D induced vector cylinder

      • Eyes with greater than 0.75 induced cylinder and 30° axis shift

    • Correcting for residual sphere using regression models, difference in UCVA not statistically significant (P=0.82)

  • Induced cylinder summary

    • Meets FDA safety guideline (< 5%, < 1% proposed)

    • Frequency and magnitude diminish over time.

    • No effect on BSCVA

    • When induced cylinder is present, UCVA is affected by approximately 1 line at 6 months and improves over time as induced cylinder resolves.

    • level of persistent induced cylinder is low (>1.00 D is 6.4% at 12 mo)

  • Endothelial cells

    • Endothelial cell loss is no more than 10%.

    • No change (within ±1%) in endothelial cell density over the course of follow-up in any region (central, midperipheral, and peripheral cornea)

    • No polymegathism or polymorphism

    • Radiofrequency energy can be safely delivered to the cornea with no effect on the endothelium.

  • Patient symptoms

    • Increase of greater than or equal to 5% in moderate-to-severe symptoms

    • Subjective questionnaire was administered at baseline and at 1, 3, 6, 9, and 12 months. Patients were asked to rate the following symptoms as none, mild, moderate, marked, or very severe: light sensitivity, headaches, pain, redness, dryness, excessive tearing, burning, foreign body sensation, glare, halos, blurred vision, double vision, fluctuation of vision, variations of vision with change in lighting, and night driving vision problems.

    • Symptoms with greater than or equal to 5% increase from baseline in moderate, marked, or very severe, at months 6, 9, and 12, included dryness, glare, halos, double vision, fluctuation of vision, and variations of vision with change in lighting.

  • Complications and adverse events [32, 36]

    • Adverse events to occur in no more than 5% of eyes; any single adverse event to occur in less than 1% of eyes

    • Recurrent corneal erosions in both eyes of 1 patient (< 1%), resolved by 3 months

    • Foreign body sensation in 1 eye of 1 patient (< 1%), reported at 9 months and resolved by 12 months

    • Pain in both eyes of 1 patient (< 1%), reported at 3 months and resolved by 6 months

    • Double/ghost images in 13 eyes of 9 patients (3%), complaint resolved in most eyes (10 out of 13 eyes)

    • Keratitis and corneal melting occurred in a single case report of conductive keratoplasty enhancement. [37]

    • Keratitis and corneal melt associated with nonsteroidal antiinflammatory topical medications occurred in a post-CK patient. [38]

    • Other complications occurring at a rate of less than 1% include blepharitis, external hordeolum, viral conjunctivitis, allergic conjunctivitis, bacterial conjunctivitis, meibomianitis, subconjunctival hemorrhage, central striae, central stromal defects, lash loss, ecchymosis, blurry vision, starbursts, headaches, film over eye, glare, halos, and light sensitivity. [39]

  • Adverse events related to device/procedure

    • Corneal perforation in 1 eye of 1 patient (< 1%) [40, 41]

      • Resulted from detachment of Teflon stop

      • Healed uneventfully; CK procedure successfully completed 2 weeks later

      • Preoperative - UCVA 20/40, mean refractive spherical equivalent (MRSE) +2.00 D

      • 12-month outcome - UCVA 20/16, MRSE 0.0 D

      • Corrective actions implemented

    • No radiofrequency energy delivered during treatment in 2 eyes of 2 patients (< 1%)

      • Resulted from poor solder joint

      • One eye successfully treated 3 weeks later

      • Preoperative - UCVA 20/200, MRSE +2.00 D

      • Twelve-month outcome - UCVA 20/32, MRSE +0.50 D

      • Second eye determined to be ineligible because of previously undetected narrow angles

      • Corrective action validated, implemented, and reviewed by FDA

  • IOP greater than 25 mm Hg in 3 eyes of 2 patients (< 1%) [42]

    • One eye of 1 patient had baseline IOP of 25 mm Hg and ineligible for enrollment

    • Two eyes of 1 patient had increased IOP that resolved without treatment or sequelae

  • Mild iritis in 1 eye of 1 patient at 7 days (< 1%), resolved without sequelae [43]

  • Decrease of BSCVA of greater than 2 lines, inferior altitudinal hemianopsia, and optic atrophy secondary to spinal surgery in 1 eye of 1 patient

  • Retinal break in 1 eye of 1 patient

    • Occurred 18 months after CK procedure

    • Successfully treated with argon laser

  • Nonophthalmic events included terminal cancer, heart attack, breast cancer, temporal arteritis, hospitalization for tonsillectomy, and nasal septum repair.

  • Maloney reported that out of 50 cases of CK, no single patient complained of dryness or haziness. [32, 36]

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Outcome and Prognosis

In 2001, McDonald and Maloney presented the interim results of the FDA Phase III clinical trial during the American Society of Cataract and Refractive Surgery (ASCRS) meeting in San Diego. Maloney reported that at 9-month follow-up, the UCVA was found to be 20/20 or better in 60% of the eyes treated and 20/40 or better in 96% of the eyes treated. In addition, 60% of the eyes were within 0.5 D of planned correction, whereas 80% of the eyes were within 1 D of planned correction. Maloney reported the absence of adverse events or complications after 9 months. McDonald reported that at 12-month follow-up, the UCVA was found to be 20/20 for 51% of the eyes treated, 20/25 for 73% of the eyes treated, and 20/40 or better for 91% of the eyes treated. [18, 44, 45, 19, 34, 36, 15, 46, 47, 48, 49, 50, 51, 52]

  • Presentation of results

    • Effectiveness was reported for eyes treated with current nomogram.

    • Safety and stability were reported for all eyes treated.

  • Effectiveness parameters [53]

    • Improvement in UCVA

      • UCVA 20/40 or better in greater than or equal to 85% of the eyes with preoperative BSCVA 20/20 or better

      • Postoperative UCVA equal to or better than preoperative BSCVA for 32% of the eyes

      • Postoperative UCVA within 1 line of preoperative BSCVA for 63% of the eyes

    • Predictability

      • MRSE within ±0.50 D for 50% of the eyes

      • MRSE within ±1.00 D for 75% of the eyes

    • Stability [54]

    • Patient satisfaction

In 2004, McDonald, Durrie, Asbell, et al, published the 6-month results of a 1-year clinical trial evaluating CK for the treatment of presbyopic symptoms in emmetropic and hyperopic eyes. [19]

  • Presentation of results

    • Of the eyes treated for near, 77% had uncorrected near vision of J3 or better at 6 months postoperatively.

    • A total of 85% of all patients had binocular distance UCVA of 20/25 or better along with J3 or better near, a combination that represents functional acuity for a presbyope.

    • Of eyes treated for near, 66% had the MRSE within ±0.50 D of intended at 6 months.

    • In 89% of eyes, the MRSE changed 0.05 D or less between 3 and 6 months postoperatively. After month 1, the incidence of variables associated with safety was 1% or lower.

    • Of patients treated, 76% were very satisfied or satisfied with their procedure.

Regression

  • Patients with previous LASIK or PRK showed a greater treatment response to CK but regressed at a similar rate as those eyes without prior LASIK or PRK. Overall, CK is a safe procedure that inevitably regresses. [55, 56, 57]

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Future and Controversies

Conductive keratoplasty is demonstrated to be safe for the treatment of presbyopia in post-LASIK patients as well as in non-LASIK patients, although longer observation in terms of factors affecting predictability is suggested. It is understood that LASIK affects the biomechanical properties and strength of the cornea, and this may be the reason for the lesser, albeit statistically insignificant, predictability. [58]

Topography-guided conductive keratoplasty may be effective in reshaping corneal configuration in eyes with keratoconus. Although the reported follow-up time is short, it theoretically may avoid or delay corneal transplantation in some cases. [59, 60]

Studies have been conducted for the safe application of conductive keratoplasty for astigmatism. [35, 61, 62, 63] Other surgical methods for the correction of hyperopia include phakic intraocular lenses (implantable contact lenses). Bifocal intraocular lenses and scleral-relaxing incision with collagen plug implantation are among the other surgical methods for the correction of presbyopia.

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