STROMAL OPACITIES
Conditions
Keywords
KERATOPLASTY, STROMAL OPACITIES
Brief summary
The purpose of this protocol is to compare and develop new surgical technique of partial-thickness corneal transplantation for treating corneal opacity. A newly developed technique, dovetail laser-assisted lamellar anterior keratoplasty (LALAK), will be tested and compared with standard full-thickness corneal transplantation, Intralase-enabled keratoplasty (IEK). The new LALAK technique replaces only the front portion of the cornea and does not have the risks associated with conventional IEK. Additionally, optical coherence tomography (OCT) will be used to guide the depth of the graft and donor dissections. The data will be analyzed to understand whether the new technique (LALAK) can repeatedly achieve good visual outcomes with lower risk from the operation compared to the visual outcomes and risk associated with the current standard of care, 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. The OCT systems to be used in this study will be the RTVue (Optovue, Inc., Fremont, CA) or the Visante (Carl Zeiss Meditec, Inc., Dublin, CA). Both are FDA-approved for the mapping of corneal thickness.
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 corneal opacities 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. Inability to give informed consent. 3. Corneal edema 4. Central guttata 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 |
|---|---|---|
| BSCVA (Snellen chart) | 24 months | A primary outcome measures will be BSCVA (Snellen chart) |
| intraoperative perforation rate | 24 months | A primary outcome measure will be intraoperative perforation rate. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| topographic astigmatism | 24 months | A secondary outcome measures will be topographic astigmatism |
| complications | 24 months | A secondary outcome measures will be complications (rejection, interface opacification, others). |
| endothelial cell count | 24 months | A secondary outcome measures will be endothelial cell count (specular microscopy) |
| interface clarity | 24 months | A secondary outcome measures will be interface clarity (masked OCT and confocal microscopy grading) |
| postoperative refractive error | 24 months | A secondary outcome measures will be postoperative refractive error |
Outcome results
None listed