Reviving the Limbus: The importance of the limbal stem cell niche & techniques to rehabilitate the ocular surface Scott G. Hauswirth, OD, FAAO Director, Ocular Surface Center, Sue Anschutz-Rogers Eye Center Assistant Professor, University of Colorado School of Medicine Mitch Ibach, OD, FAAO Vance Thompson Vision Please silence all mobile devices and remove items from chairs so others can sit. Unauthorized recording of this session is prohibited.
Disclosure Statement: Mitch Ibach, OD: Alcon(s); Equinox(in); Glaukos(c,s) Scott G. Hauswirth, OD: Allergan(c,s); Avedro(c,s); BioTissue(c); Glaukos(c); Mentholatum(c); OcuTherm(i); Shire(c,s); Sight Sciences(c,i); Sun(c); TearScience(c); Terrapin Ocular(i) C = consultant; S = speaker; I = investigator; Investor = (In) Some of the material in this course may depict drugs or devices which are used in an off-label fashion. This is not intended to be promotional and is merely a representation of the author s clinical experience.
Anatomy: Intro to the Limbus Definition: border between cornea and sclera Histology - Anterior: line between ending of Bowman s and Descemet s membrane Posterior: perpendicular line from scleral spur, relative to external surface of globe
Anatomy: Limbus Limbal thickness may vary by: aging(1), ethnicity (2) and even by region on the cornea (2) Accepted values: 1-2mm average, but is thicker in superior quadrant and thinnest in nasal-temporal regions Qihua: Caucasian 32.8% longer than Han Chinese Small sample, but little research has been done in this area 1) Yang Y, et al. Age-related changes in human corneal epithelial thickness measured with anterior segment optical coherence tomography. IOVS. 2014;55:5032-5038. 2) Qihua LE, et al. In vivo evaluation of the limbus using anterior segment optical coherence tomography. Transl Vis Sci Tech. 2018 Jul;7(4):12.
Anatomy: Limbal Stem Cell Niche LSCs account for only small % of cells in the limbus 1 TACs Melanocytes Specifically at limbal epithelium Langerhans cells* Sentinel cells for antigen processing Mediate T-cell immune response Basement membrane LEC anchorage Mesenchymal cells penetrate to form N-cahedrin (homeostasis) Vascular*/neurological * - especially important for graft survival 1. Latta L, et al. Human aniridia limbal epithelial cells lack expression of keratins K3 and K12. Exp Eye Res. 2018 Feb;167():100-109.
Purpose of Limbal Stem Cells Differentiate to corneal epithelium via following process: LSC(basal) => TAC Migrate across and upwards, centripitally Centripital epithelial migration (Nejad, et al. 2014)
Factors affecting LSCN Inflammation and trauma Cytokines Growth factors bfgf TGF-B3 PDGF VEGF
Disease impacting LCSN Inflammatory Stevens-Johnson Syndrome Ocular Ciccatricial Pemphigoid Graft-Versus-Host Disease Infectious HSV Trachoma Traumatic Chemical insult* Thermal burns* Contact lens wear* Cryotherapy Radiation* Congenital Aniridia, Peter s Anomaly, PAX6 mutations
Limbal Stem Cell Deficiency Insult to limbal stem cell niche alters ability to regenerate healthy corneal epithelium Results in scarring, opacification, and conjunctivalization of cornea Common sequelae: Persistent epithelial defects Pannus/neovascularization Opacification Corneal melt Attallah MR, et al. Clin Ophthalmol. 2016 Apr
Clinical signs of LSCD Inflammation/hyperemia of affected sector(s) Edema of affected limbal area Whorl-like keratopathy Sectoral in mild cases Involving entirety of cornea in severe cases Neovascularization Opacification of cornea Conjunctivalization of cornea
Severity of LSCD on Slit Lamp Exam Lee, Q., Xu, J., & Deng, S. (2018). The diagnosis of limbal stem cell deficiency. The Ocular Surface, 16, 58-69.
Alternative methods for Diagnosis of LSCD AS - OCT Impression Cytology Histology review of ocular surface (Giemsa stain) Goblet cells on a corneal specimen for impression cytology (very accurate) Lee, Q., Xu, J., & Deng, S. (2018). The diagnosis of limbal stem cell deficiency. The Ocular Surface, 16, 58-69.
Treatment Options: LCSD Early/mild cases may be managed medically More severe cases require surgical intervention Non-surgical Lubrication Optimization of ocular surface Anti-inflammatories Scleral Contact Lens Regenerative Autologous serum Amniotic membrane Surgical Limbal stem cell transplant Keratoprosthesis
Evidence to support medical management Kim, et al. 22 eyes, minimum 3 mo FU Inclusion based on clinical appearance of LSCD Primary inciting (18% unknown) SCL only 59% SCL + rosacea 14% Toxicity (BAK) 9% Resolution by: Lubrication only (4) Antiinflammatory therapy (18) Kim BY, et al. Medically reversible limbal stem cell disease: clinical features and management strategies. Ophthalmol. 2014 Oct;121(10):2053-2058.
Immunomodulation in LSCD Used to control inflammatory response in LSCD Restores more quiet microenvironment Quiet possible inciting event usually inflammatory component Topical steroids Cyclosporine-A Lifitigrast
Ocular Surface Optimization in LSCD Demonstrable improvement with: Topical immunomodulation (Restasis, etc) Punctal occlusion Lid hygiene Warm compress therapy MG procedures (LipiFlow, IPL, etc)
Amniotic Membrane Grafts 1. Anti-inflammatory 2. Anti-scarring 3. Anti-angiogenesis (new blood vessel growth) 4. Re-epithelialization http://www.nature.com/eye/journal/v23/n10/fig_tab/eye200841 0f2.html
What is amniotic membrane? Inner layer of the placenta Avascular connective tissue Epithelial cells on a basement membrane which resides over a stromal matrix Made of collagen, fibronectin, laminin Growth factors Anti-inflammatory components Kenyon, K. R., & Lam, H. (2013, June 1). Amniotic Membrane: Themes and Variations. Ophthalmology Management, 1-6.
Amniotic Membrane Grafts (AMG) Biotissue- Prokera, Amniograft, & Amnioguard IOP Ophthalmics- Ambiodisk http://www.biotissue.com/products/prokera.aspx http://www.iopinc.com/store/ambiodisk/
Clinical Usage 1. Insertion Prokera vs. AmbioDisk 2. Time-frame to reabsorption = 7-14 days. Resorption will be faster in neovascularized or very inflammed eyes. More inflammatory cytokines will dissolve the graft faster. 3. Prokeraà remove ring in clinic. Ambiodiskà remove BCL Kenyon, K. R., & Lam, H. (2013, June 1). Amniotic Membrane: Themes and Variations. Ophthalmology Management, 1-6.
Amniotic Membrane Prokera Role in LSCD Anti-inflammatory Anti-scarring Anti-angiogenesis Aids in epithelialization
Surgical Options CLAL KLAL CLET SLET C-KLAL Conjunctival Limbal Autograft / Allograft Keratolimbal Autograft / Allograft Cultivated Limbal Epithelial Transplantation Simple Limbal Epithelial Transplantation Combined Conjunctival Keratolimbal Allograft
How to know? History of previous CL or previous ocular surgery contradiction to CLAL or SLET Disease etiology plays important role Minimal to no conj involvement SLET/KLAL With conjunctival involvement lr-clal, CLAL(auto), Kpro2
Cincinnati OSST Decision Tree How to know what surgery fits best? Decision tree based on several factors: ABO typing HLA typing Panel Reactive Antibody (PRA) DSA (unacceptable antigens) If antigen matching with no DSA, low PRA, lr-clal preferred Otherwise, KLAL with systemic immunosuppression
Patient selection: Cincinnati OSST 142 eyes, 104 patients retrospective chart review Donor selection maximizes impact and graft survival HLA Class I: HLA-A, HLA-B HLA Class II: HLA-DR, HLA-DQ Recommended that patients undergo: Living relative donor (lr-clal) 1 st choice Harvesting at 5:00 to avoid inducing LCSD
Keratolimbal allograft (KLAL) Keratolimbal Allograft More than 270 degrees of LCSD Common conditions Chemical Injuries Congenital Aniridia Stevens Johnson Syndrome Other conditions that may require partial KLAL Recurrent pterygia Prior contact lens related stem cell deficiency Prior Intra/Extra cap surgery with extensive cautery
Video: KLAL Courtesy David Hardten, MD
KLAL: Postoperative Care 1 day: Clean lashes, tactile IOP, drop regimen Oral Prednisone usually 2-3 month taper Topical Steroid q2 hours 1 wk, then QID 3-4 months, usually BID long term Antibiotic QID 1 wk, then BID 2 months Tacrolimus 0.03% BID start at 1 wk Higher risk cases might consider systemic immunosuppression Tacrolimus 4mg po BID, Mycophenolate: 1 gram po BID Consider meds to reduce opportunistic infection: Valganciclovir 225mg daily and Trimethoprim/sulfamethoxazole single strength 3 x per week or Dapsone 100mg daily 1 week Clean lashes, tactile IOP, drop regimen 1 month i-care IOP usually possible, remove tarsorrhaphy sutures, leave BSCL in place 2 months - i-care IOP usually possible, remove BSCL, trim amnion if needed, but usually has dissolved 4 months topography, adjust medications, RGP?
CLAL/CLET Cultivated Limbal Epithelial Transplant
SLET: Procedure Approach: Simple Limbal Epithelial Transplant (SLET) 1 surgery Lowest risk when <4-6 clock hours are involved Steps: Donor limbal tissue resected from healthy eye 2 x 2mm piece, chopped into ~0.25mm pieces Recipient cornea 360 degree peritomy Recipient cornea denuded of any fibrosis/conjunctivalization Amniotic membrane overly (suture/glue) Limbal pieces dropped onto membrane Second amniotic membrane overlay 2 Contact lens overlay 1) Sangwan VS, et al. Br J Ophthlamol 2012 Jul 2) Amescua G, et al. Am J Ophthalmol. 2014 Sept
SLET: Outcomes Pilot study by Sangwan, et al., 2011 6 eyes, mean follow up 9.2mo +/- 1.9 mo Baseline VA >20/200 in all eyes Final VA =<20/60 in 4/6, Vazirani, Br J Ophthalmol Oct 2016 68 eyes Success in 83.8% (completely epithelialized, avascular corneal surface) Symblepharon associated with worse prognosis Focal recurrence of pannus in 36.8%
Video: SLET Courtesy Darren Gregory, MD
Amniotic Membrane Graft (AMG) vs. AMG + SLET
Postoperative management Week 1-6: amnion dissolving + CL poor VA Steroid/antibiotic drops, ointment Doxycycline PO, Vit C Wait for re-epithelialization before removal of CL Week 6-12 Taper steroid Continue aggressive ocular surface management Pre-op 1 day post SLET 6 wks postop 6 mo postop 1 year postop
Obstacles Immunologic rejection Not present in SLET and autologous grafts Reduced in antigen-matched donors Significant issue in cadaver donor Chronic immunosuppression Hepatotoxicity Nephrotoxicity Failure Two donor eyes 2 years post LSC-excision for SLET
Treatment of LSCD Replacement of pluripotent stem cells differentiated into LSC Not yet ready for prime time 1. Sareen D, et al. Differentiation of human limbal-derived induced pluripotent stem cells into limbal-like epithelium. Stem Cells Transl Med. 2014;3:1002-1012.
Thank you! Questions? Scott.Hauswirth@ucdenver.edu Mitch.Ibach@VanceThompsonVision.com
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