- 17 Sep, 2024
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Overview of Conductive Keratoplasty
Conductive Keratoplasty
Conductive keratoplasty is a relatively new technique among refractive corneal procedures
and can be used for the correction of hyperopia and presbyopia.
Overview of Conductive Keratoplasty
In the ever-evolving field of ophthalmology, technologies come and go as the day goes by.
However, it takes a particular achievement in a new technology to make a considerable impact
on the world of ophthalmology today.
One of these great achievements can be seen through conductive keratoplasty.
Conductive keratoplasty (CK) is a minimally invasive procedure that uses the controlled
release of radiofrequency (RF) energy to reshape the corneal stroma through the creation
of uniformly spaced and continuous collagen shrinkage spots.
In late October 2004, the United States Food and Drug Administration officially approved
the use of conductive keratoplasty for the treatment of mild to moderate hyperopia.
This has made conductive keratoplasty the very first and only non-laser vision correction
procedure approved for the treatment of this particular kind of refractive error.
Not only that, it also makes conductive keratoplasty the very first and only non-laser procedure
that gained the approval of the FDA for any kind of presbyopia, a newly defined medical term.
The approval of conductive keratoplasty in the treatment of presbyopia has made this technology
the very first and only type of vision correction procedure approved by the FDA for this particular eye condition.
Benefits of Conductive Keratoplasty
Apart from the apparent advantage of reducing dependency on glasses or contact lenses,
conductive keratoplasty boasts several other benefits over other eye refractive
procedures such as laser-aided in-situ keratomileusis, photorefractive keratectomy or astigmatic keratotomy.
Unlike many of these procedures, this technique doesn’t offer to alter the shape of the cornea permanently.
Other benefits include minimal patient discomfort and the immediate impact of the treatment on sight.
Unlike some of the more aggressive laser procedures, there is no damage to the integrity
or strength of the cornea and hence no pain during or after the treatment.
Furthermore, there is no need for any injections or cutting of the cornea; only topical anesthetic
in the form of eye drops needs to be used. Because it is so gentle and stress-free,
conductive keratoplasty is often known as “no touch” vision correction.
The low complication rate for CK makes it an attractive choice for both patients and clinicians.
With the more intrusive laser refractive procedures, there is a relatively high chance of each eye
healing at different rates which leads to an imbalance in vision and an increase in the risk of unpredictable results.
However, with CK, no significant complications have been reported and the recovery time is short.
Immediately after the procedure, the patient can return to their everyday life; no post-operative hospitalization,
eye patching, or time off work is necessary.
This ties into another key benefit in that the treatment time for conductive keratoplasty
is very short and is easily manageable for both patient and doctor.
A typical procedure to one eye takes about 7 minutes and, because only mild anesthetic drops are required,
there is little or no preparation and the patient can return home as soon as they feel ready to go.
Scope of the conductive keratoplasty Training Course
The conductive keratoplasty training course provides a comprehensive understanding
of the conductive keratoplasty procedure, with both theoretical and practical sessions.
Trainees will learn the anatomy of the eye, the principles of the procedure,
and details of the equipment used.
They will also learn how to evaluate patients for the procedure, effective treatment planning,
and patient management strategies.
The Conductive Keratoplasty Training Course Curriculum Includes:
Patient Selection Criteria:
1- Realistic patient expectations. The patient’s expectations of conductive keratoplasty
should be discussed and managed.
It should be emphasized that CK is a procedure meant to reduce a patient’s dependency
on reading glasses.
Although it might reduce hyperopia, the main aim of CK is to improve near vision and not distance vision
2- Corneal pachymetry. The minimal central corneal thickness should be at least 525 microns.
This will ensure that there is enough corneal tissue to ablate and still maintain corneal integrity.
3- Stable refraction. As patients are usually older, it is important to ensure that their refraction is stable.
Patients should not have had a significant change in their sphere power or cylinder power
of more than 0.5 diopters over the last year.
Life events such as pregnancy or the onset of diabetes should be noted as these conditions could affect the refraction.
4- Refraction. A manifest refraction of +0.75 diopters to +2.00 diopters of sphere presbyopia should be present
. Also, the patient should have 1.0 diopters to 2.0 diopters of sphere hyperopia.
5- Age. Patients should be more than 40 years old.
On the other hand, apart from the routine preoperative investigations, several specific tests are required
for the conductive keratoplasty procedure. This will include the presence of dry eyes,
intraocular pressures, endothelial cell count, corneal topography, and pachymetry.
Patients should be given ample time to ask any questions about the procedures
and they must sign the consent form on their operative eye.
Last but not least, doctors and healthcare providers should take note that the success
of conductive keratoplasty is not solely determined by surgical techniques
but also by good postoperative care and follow-up.
Patients are required to attend a series of postoperative follow-ups and appropriate
measures will be taken place if the patient develops complications.
It is the astute practitioners’ responsibility to ensure patients’ queries are answered
and doubts are cleared during the preoperative assessment.
By educating patients and letting them grasp the possible outcome of the procedures,
the bond between patients and healthcare providers will be strengthened.
Preoperative Assessment and Evaluation:
During preoperative assessment and evaluation, instructors will provide a detailed overview
of how to read topography and wavefront maps to confirm the presence and extent of astigmatism.
At the beginning of the training, participants will be introduced to different types of diagnostic
equipment and imaging systems that are used preoperatively,
such as topography, wave front sensing, and auto-refraction.
During the coure provided by MoAcademy, there will be actual demonstrations on how to read the output
from these machines and translate that into the selection of treatment patterns versus
conventional astigmatism correction.
In addition, participants will also learn the measurement of pupil size and techniques
for accurate evaluation of the optical zones.
Pupil sizes help to rule out candidates with large pupils that may result in night vision
disturbances postoperatively.
Through the practical microscopy sessions, participants will have the chance to explore
the mechanisms that rule out those with decentered or greater than 50% depth of scar
within the 6mm optical zone of treatment.
Techniques and Procedures of Conductive Keratoplasty
Administration of anesthetic drops will be the first step of the live procedure; the type of anesthesia
being used will be explained and the technique for its administration demonstrated.
A demonstration of the placement of the patient’s eyelid speculum will be given,
along with advice on how to secure each eyelid effectively.
The ophthalmic drape will be built up, and the stage of creating a fenestration will be shown.
Wetting of the lid speculum to avoid corneal abrasion will be mentioned.
The use of an anesthetic to extend the eyelid speculum and being regularly at eye level
with the patient will also be explained.
Most importantly, the strategy for making and sizing the corneal pocket will be demonstrated.
The process of transferring the heat from the probe to the corneal stromal tissue and the formation
of a collagen band will be demonstrated.
After treatment, the laser unit will be disconnected from the eye and the completion of the procedure will be discussed.
Surgical Instruments and Equipment
The two special instruments required for conductive keratoplasty are the hand-held transmitter
and the foot-controlled transmitter.
The hand-held transmitter delivers radiofrequency energy to the corneal stroma while
the foot-controlled transmitter allows the surgeon to activate the energy application with minimal vibration.
The hand-held transmitter is a bipolar device so it only allows the transfer
of energy between the two ends of the probe.
This is important for safety reasons as it prevents any damage to tissues in the event
of accidental contact between the activated probe and any other metallic instrument.
Step-by-Step Procedure of Conductive Keratoplasty
The first part of the procedure is to select an appropriate patient and obtain informed consent.
Then, the patient’s eye is anesthetized using topical anesthetic drops and the patient
is asked to look directly at a fixed light in the microscope.
The eyelids are gently held open with an instrument called a lid speculum.
Once the eye is properly aligned under the microscope, the surgeon uses a special marker
called a trephine to place marks on the cornea.
The patient’s head and the microscope are then moved to a different position to place more marks circularly.
The depth of treatment is then adjusted on the laser console based on the patient’s refractive error,
and the circular pattern of spots is placed in the cornea with the help of the laser.
There are a total of eight spots that are placed around the periphery of the cornea, which are connected.
Once the eye has properly aligned under the laser and the treatment parameters are being set,
the patient should not move the head to keep the proper alignment throughout the procedure.
After the treatment, antibiotic drops and mild steroid drops are instilled, and the eye is patched.
The patient is then given an eye shield to be worn while sleeping.
Postoperative Care and Follow-up
Postoperative follow-up care is crucial in ensuring an optimal outcome.
On the first day following surgery, patients may report mild discomfort and fluctuating vision.
They should be instructed to go home and take a nap.
All patients should be reviewed at one week and four weeks postoperatively.
It is recommended that a log be kept of the patient’s visual acuity results,
which will aid the assessment of the long-term follow-up records.
They should be advised to abstain from eye makeup for 1 week.
Swimming in public pools and using a sauna should be avoided for 2 weeks.
Mild stable keratometric changes continue to occur over the first 3 months.
The surgeon should be aware that, if necessary, the effect of subsequent resumption
of corneal rigidity may eventually mask the effect of CK.
However, after 3 months postoperatively, the surgeon may now be in a position to assess
the success of the treatment, as corneal stability and refraction reach a plateau.
At three months postoperatively, the patient should have had some improvement in unaided v
isual acuity and best-corrected vision, compared to the preoperative values.
The full benefit of CK takes place at around 3 months.
All clinicians performing conductive keratoplasty should be capable of carrying forward
the management of any infections.
It must be recognized that any delay in the initiation of proper treatment may lead to irreversible
damage to the cornea and the patient’s sight.
Proper risk management policies must be adopted by the clinical practice involving conductive
keratoplasty to ensure that all clinicians maintain a safe working environment and that any adverse
events are promptly and satisfactorily handled.