Corneal Opacity, Keratoconus
Conditions
Keywords
Keratoconus, Corneal Opacity, Keratoplasty
Brief summary
The purpose of this study is to determine if a new procedure, called laser-assisted lamellar anterior keratoplasty (LALAK), can achieve the same level of vision with a lower risk of potential complications after surgery compared to another corneal transplant procedure. The current procedure is called Intralase-enabled keratoplasty (IEK) and replaces the entire cornea. The LALAK procedure involves transplanting only the top layers of the cornea instead of the entire cornea. Only one eye will have this experimental procedure performed. If both eyes need to have surgery your doctor will help you decide on the best non-study option for your other eye.
Detailed description
Corneal transplantation (keratoplasty) is the most common organ transplant, with 42,606 procedures in the U.S. in 2009. Many surgeons are moving away from full thickness corneal transplantation, also called penetrating keratoplasty (PK), because of risks involving rejection, irregular astigmatism and wound dehiscence. They are moving towards partial thickness (lamellar) transplantations of either the anterior or posterior (endothelial) layers, which can reduce these risks. The femtosecond laser has been used to create excellent tongue-in-groove junctions between the graft and host in full thickness PK.1 This technique, called IEK (Intralase-enabled keratoplasty), has now become a standard surgical procedure. The tongue-in-groove junction achieved at the circumferential edge of the graft and host leads to a continuous smooth anterior surface and strong wound healing. The new technique is called dovetail LALAK. In this technique, the femtosecond laser is used to create a 31% anterior lamellar graft with dove tailed side cuts. It is also used to create a shallow anterior lamellar dissection and beveled side cuts on the recipient cornea to match with the dovetail graft. In the new technique, the depth of the graft and donor dissections will be guided by OCT measurements. The proposed trial will test if the new technique can reproducibly achieve good visual outcomes without the risk of rejection. The outcome of the LALAK procedure will be compared to that of IEK.
Interventions
PROCEDURELALAK
1. A dovetail shaped cut will be made on the graft using a femtosecond laser at the eye bank. The cut depth will be proportional to the central stromal thickness of the graft. This graft will be separated from stromal bed by eye bank personnel for examination of the cut surface. High-quality graft will be replaced in preservation medium and shipped to the surgeon prior to surgery. 2. The host cornea will receive femtosecond laser cut consisting of a shallow lamellar cut with angled side cut to match the dovetail graft in a tongue-in-groove fashion. The femtosecond laser treatments will be performed under topical anesthesia in the laser suite. The femtosecond laser is an FDA-approved device for use in this indication (corneal transplantation including lamellar keratoplasty). A protective eye shield is placed over the eye. The graft will be sutured into the host bed.
PROCEDUREIEK
1. A full thickness graft will be prepared at the eye bank with zigzag side cuts prepared with a femtosecond laser. The graft is separated from the rim, replaced in the preservation medium, and shipped to the surgeon prior to the surgery. 2. In the laser suite, the host cornea will be cut with the femtosecond laser with zigzag side cuts leaving a 70-100 micron bridge. A protective eye shield is placed over the eye. The graft will be sutured into the host bed.
DEVICEoptical coherence tomography (OCT)
OCT will be used to guide the depth of the graft and donor dissections.
DEVICEfemtosecond laser
The femtosecond laser system to be used in this study for host cornea preparation will be the Intralase FS system (iFS, AMO, Inc., Santa Ana, CA). The iFS is FDA-approved for corneal surgery including full thickness and lamellar keratoplasty. Eye banks use earlier versions of the Intralase system which are also FDA approved for this indication.
Sponsors
National Institutes of Health (NIH)
National Eye Institute (NEI)
Oregon Health and Science University
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 100 Years
Healthy volunteers
No
Inclusion criteria
* Eyes with keratoconus that cannot be adequately or safely corrected with spectacles, contact lens or excimer laser surface ablation. The cornea must have healthy endothelium (endothelial cell density \> 1,500/mm2).
Exclusion criteria
1. Preoperative corneal thickness less than 400 microns. 2. Corneal edema 3. Central guttata 4. Inability to give informed consent. 5. Inability to maintain stable fixation for OCT imaging. 6. Inability to commit to required visits to complete the study. 7. Eyes with concurrent cataract, retinal diseases, glaucoma, or other eye conditions that may limit the visual outcome after surgery. 8. Patients with severe collagen vascular diseases or ocular surface disorders
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Does LALAK Achieve the Same Level of Post-operative BSCVA as IEK. | 24 months | The primary goal of the trial is to determine if LALAK can achieve the same level of postoperative Best Spectacle Corrected Visual Acuity (BSCVA) guided by OCT as IEK. The BSCVA will be measured using a clinic Snellen chart and recorded in the typical Snellen fraction (20/xx) in feet. This will be converted to logMAR form for statistical analysis. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Laser-assisted Lamellar Anterior Keratoplasty LALAK: a. A dovetail shaped cut will be made on the graft using a femtosecond laser at the eye bank. The cut depth will be proportional to the central stromal thickness of the graft. This graft will be separated from stromal bed by eye bank personnel for examination of the cut surface.
b. The host cornea will receive femtosecond laser cut consisting of a shallow lamellar cut with angled side cut to match the dovetail graft in a tongue-in-groove fashion. The FDA-approved femtosecond laser treatments will be performed under topical anesthesia in the laser suite.
optical coherence tomography (OCT): OCT will be used to guide the depth of the graft and donor dissections.
Topical Anesthesia
femtosecond laser: The femtosecond laser system to be used in this study for host cornea preparation will be the Intralase FS system (iFS, AMO, Inc., Santa Ana, CA). The iFS is FDA-approved for corneal surgery including full thickness and lamellar keratoplasty. | 3 |
| Intralase-enabled Keratoplasty IEK: a. A full thickness graft will be prepared at the eye bank with zigzag side cuts prepared with a femtosecond laser. The graft is separated from the rim, replaced in the preservation medium, and shipped to the surgeon prior to the surgery.
b. In the laser suite, the host cornea will be cut with the femtosecond laser with zigzag side cuts leaving a 70-100 micron bridge. A protective eye shield is placed over the eye. The graft will be sutured into the host bed.
Retrobulbar Block or General Anesthesia
femtosecond laser: The femtosecond laser system to be used in this study for host cornea preparation will be the Intralase FS system (iFS, AMO, Inc., Santa Ana, CA). The iFS is FDA-approved for corneal surgery including full thickness and lamellar keratoplasty. Eye banks use earlier versions of the Intralase system which are also FDA approved for this indication. | 2 |
| Total | 5 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Adverse Event | 0 | 1 |
| Overall Study | Lost to Follow-up | 1 | 0 |
| Overall Study | Screen Fail | 1 | 0 |
Baseline characteristics
| Characteristic | Laser-assisted Lamellar Anterior Keratoplasty | Intralase-enabled Keratoplasty | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 3 Participants | 2 Participants | 5 Participants |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants | 0 Participants | 1 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 2 Participants | 2 Participants | 4 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 3 Participants | 2 Participants | 5 Participants |
| Region of Enrollment United States | 3 participants | 2 participants | 5 participants |
| Sex: Female, Male Female | 2 Participants | 1 Participants | 3 Participants |
| Sex: Female, Male Male | 1 Participants | 1 Participants | 2 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 2 | 0 / 2 |
| other Total, other adverse events | 2 / 2 | 0 / 2 |
| serious Total, serious adverse events | 0 / 2 | 0 / 2 |
Outcome results
Primary
Does LALAK Achieve the Same Level of Post-operative BSCVA as IEK.
The primary goal of the trial is to determine if LALAK can achieve the same level of postoperative Best Spectacle Corrected Visual Acuity (BSCVA) guided by OCT as IEK. The BSCVA will be measured using a clinic Snellen chart and recorded in the typical Snellen fraction (20/xx) in feet. This will be converted to logMAR form for statistical analysis.
Time frame: 24 months
Population: For the LALAK group, there were 3 subjects enrolled, but one was a screen fail so no data was obtained for that subject.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Laser-assisted Lamellar Anterior Keratoplasty | Does LALAK Achieve the Same Level of Post-operative BSCVA as IEK. | 0.7 logMAR unit |
| Intralase-enabled Keratoplasty | Does LALAK Achieve the Same Level of Post-operative BSCVA as IEK. | 0.05 logMAR unit |