Limbal Stem Cell Deficiency (LSCD) is a blinding disease that accounts for an estimated 15-20% of corneal blindness worldwide. Current treatments are limited. Traditional corneal transplantation with penetrating keratoplasty (PKP) is ineffective in treating these patients. Without a healthy population of limbal stem cells (LSC) to regenerate the corneal epithelium, standard corneal transplants will not re-epithelialize and will rapidly scar over or melt. The limbal niche is the microenvironment surrounding the LSCs that is critical for maintaining their survival and proliferative potential under physiologic conditions. Extracellular signals from the microenvironment are critical to the normal function and maintenance of pluripotent stem cells. Identifying an effective niche replacement is thus an important focus of limbal stem cell research and critical for advancing treatments for LSCD. Descemet's membrane (DM), an acellular, naturally occurring, basement membrane found on the posterior surface of the cornea, is a promising niche replacement. DM is routinely isolated and transplanted intraocularly with associated donor corneal endothelium for treatment of diseases like Fuchs' dystrophy and corneal bullous keratopathy that specifically affect DM and corneal endothelium. However, its application on the ocular surface has not been explored. DM is optically clear and highly resistant to collagenase digestion. This makes it very attractive as a long-term corneal on-lay and niche replacement on the surface of the eye. The anterior fetal banded layer of DM shares key compositional similarities with limbal basement membrane, which is a major component of the limbal niche. These similarities include limbus-specific extracellular matrix proteins such as collagen IV that is restricted to the α1, α2 subtypes, vitronectin, and BM40/SPARC. Of these, vitronectin and BM40/SPARC are known to promote proliferation of LSCs and induced pluripotent stem cells (iPSC) in culture. Because of this, DM is a promising biological membrane for establishing a niche-like substrate on the corneal surface in patients with LSCD. The purpose of this pilot study is to investigate the clinical efficacy of using DM as a corneal on-lay to promote corneal re-epithelialization in partial LSCD.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
19
The worst seeing eye of these patients (or a randomized eye if vision is equal bilaterally) will be treated with superficial keratectomy to remove any pannus and debride the central corneal epithelium, followed by transplantation of a Descemet's membrane corneal onlay. Patient will be followed for 6 months and evaluated for improvement in visual acuity and improvement in limbal stem cell deficiency, and monitored for adverse events.
The worst seeing eye of these patients (or a randomized eye if vision is equal bilaterally) will be treated with superficial keratectomy to remove any pannus and debride the central corneal epithelium, followed by transplantation of a Descemet's membrane (DM) corneal onlay. Patient will be followed for 6 months and evaluated for improvement in visual acuity, limbal stem cell deficiency, and persistent epithelial defects/recurrent erosions, and monitored for adverse events.
University of Minnesota
Minneapolis, Minnesota, United States
Visual improvement
Visual Acuity: Improvement in visual acuity over time will be measured as the difference in post-op visual acuity at post-operative week 1, month 1, month 3, and month 6 compared to pre-op visual acuity. Visual acuity will be assessed in study eyes with a standard Snellen Eye Chart.
Time frame: 180 days following intervention
Graft Retention on Slit Lamp Examination
Retention of the graft: Retention of the graft on the surface of the eye will be documented as present, absent, or indeterminant using slit lamp examination. For slit lamp examination, retention of the graft will be evidenced by visualization of a gentian violet orientation mark (s-stamp) that will be placed on all grafts at the time of tissue processing by the eye bank (prior to transplantation).
Time frame: 180 days following intervention
Graft Retention on Slit Lamp Photography.
Retention of the graft: In order to maintain photographic proof of the findings on slit lamp examination, slit lamp photography will also be taken. Study eyes will be photographed at the slit lamp at post-operative week 1, month 1, month 3, and month 6. Retention of the graft will be evidenced by visualization of a gentian violet orientation mark (s-stamp) that will be placed on all grafts at the time of tissue processing by the eye bank (prior to transplantation). This photographic documentation will assist in confirming the findings in outcome measure #2.
Time frame: 180 days following intervention
Incidence of Post-operative Adverse Events Requiring Treatment
Post-operative adverse events: Patients will be assessed at slit lamp at post-operative week 1, month 1, month 3, and month 6 for dislocation or opacification of the DM corneal onlay, PEDs, elevated intraocular pressure (IOP), and/or infectious keratitis to assess the safety of the therapy. Any persistent epithelial defect will be measured for size on slit lamp by recording the long and short diameter of any defect. IOP will be measured using a Goldman applanation. Infectious keratitis and membrane dislocation will be assessed at slit lamp during each post-operative visit.
Time frame: 180 days following intervention
Corneal Neovascularization on Slit Lamp Examination
Corneal Neovascularization: will be evaluated using slit lamp examination pre-operatively and post-operatively at week 1, month 1, month 3, and month 6. The degree of corneal neovascularization will be quantified using a previously established 10-point slit lamp examination score based on the extent of limbal involvement (number of quadrants involved - up to 4 points), the extent of corneal surface involvement (total area of corneal involved - up to 4 points), and whether the central visual axis is involved (up to 2 points).
Time frame: 180 days following intervention
Corneal Neovascularization on Slit Lamp Photography
In order to maintain photographic proof of the findings on slit lamp examination, slit lamp photography will also be taken. Photos will be taken pre-operatively and post-operatively at week 1, month 1, month 3, and month 6. The degree of corneal neovascularization on the photos will be compared to the documented 10-point slit lamp examination score from outcomes measure #6 to confirm the accuracy of the results. Again, the 10-point slit lamp examination score is based on the extent of limbal involvement (number of quadrants involved - up to 4 points), the extent of corneal surface involvement (total area of corneal involved - up to 4 points), and whether the central visual axis is involved (up to 2 points).
Time frame: 180 days following intervention
Corneal Epitheliopathy on Slit Lamp Examination
Corneal Epitheliopathy: will be evaluated using slit lamp examination pre-operatively and post-operatively at week 1, month 1, month 3, and month 6. The degree of corneal epitheliopathy will be quantified using a previously established 10-point slit lamp examination score based on the extent of limbal involvement (number of quadrants involved - up to 4 points), the extent of corneal surface involvement (total area of corneal involved - up to 4 points), and whether the central visual axis is involved (up to 2 points).
Time frame: 180 days following intervention
Corneal Epitheliopathy on Slit Lamp Photography
In order to maintain photographic proof of the findings on slit lamp examination, slit lamp photography will also be taken. Photos will be taken pre-operatively and post-operatively at week 1, month 1, month 3, and month 6. The degree of corneal epitheliopathy on the photos will be compared to the documented 10-point slit lamp examination score from outcomes measure #8 to confirm the accuracy of the results. Again, the 10-point slit lamp examination score is based on the extent of limbal involvement (number of quadrants involved - up to 4 points), the extent of corneal surface involvement (total area of corneal involved - up to 4 points), and whether the central visual axis is involved (up to 2 points).
Time frame: 180 days following intervention
Corneal epithelial thickness
Corneal epithelial thickness will be assessed as a metric of LSCD severity. Corneal epithelial thickness will be measured in cross-section on AS-OCT only.
Time frame: 180 days following intervention
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