CT&WHing_Part2b_Corneal Wound Healing_2020BB - Tagged.pdf
Transcript
WOUND HEALING IN THE EYE Cornea – PKP, LASIK Lens – post cataract surgery Glaucoma filtration surgery Proliferative vitreoretinopathy Laser photocoagulation etc etc CORNEAL WOUND HEALING INFECTION RAPID HEALING RESPONSE TRAUMA...
WOUND HEALING IN THE EYE Cornea – PKP, LASIK Lens – post cataract surgery Glaucoma filtration surgery Proliferative vitreoretinopathy Laser photocoagulation etc etc CORNEAL WOUND HEALING INFECTION RAPID HEALING RESPONSE TRAUMA TRANSPARENCY KERATOPLASTY STRENGTH REFRACTIVE SURGERY STABILITY Nature and extent of the wound healing response is dependent on: Cause Type chemical superficial mechanical penetrating Refractive & Transplant surgery Photorefractive keratectomy (PRK) Laser-assisted in situ keratomileusis (LASIK) Laser-assisted sub-epithelial keratectomy (LASEK) Penetrating keratoplasty (PKP) Anterior lamellar keratoplasty (ALK) Photorefractive Laser assisted in situ Laser-assisted sub-epithelial keratometry (PRK) keratomileusis (LASIK) keratectomy (LASEK) (Cursoenarm.net n.d.) Degrees of Haze Trace Mild Moderate Penetrating keratoplasty (PKP) /Corneal transplantation Full thickness transplant Replaces diseased cornea www.allaboutvision.com Especially in cases of endothelial cell dysfunction www.msdmanuals.com Anterior lamellar keratoplasty (ALK) Partial thickness graft (epithelium and stroma) Stromal pathologies without endothelial dysfunction Epithelial Wound Healing Rounding off of wound edge, epithelial differentiation disappears Stem cells & TACs proliferate (includes cells next to wound edge) Loss of cell attachments: hemidesmosomes Migration as a sheet (c.16 mm/hr), along temporary matrix Re-epithelialisation & contact inhibition; hemidesmosomes reformed Epithelial differentiation/stratification 3-7 days Stromal Wound Healing keratocyte apoptosis at wound site activation & proliferation of fibroblasts migration to wound site differentiation‘myofibroblast’ ECM remodelling: New synthesis of GAGs & collagen and degradation fibrosis and ‘haze’ loss of vision Return to normal (1-3 years!?) Endothelial Healing Required if damaged human corneal endothelial cells are unable to regenerate Migrate across Descemet’s membrane to compensate regions of loss Enlarge to fill in gaps => polymegathism & pleomorphism occurs Density of 500 endothelial cells per mm2 required for cornea to remain transparent https:// webeye.ophth.uiowa.edu Regulators of Corneal Wound Healing tear fluid growth factors adhesion molecules proteolytic enzymes Epithelial-stromal interactions are important in corneal wound healing Myofibroblasts Basement membrane defect (Spadea et al. 2016)
