Cornea is the clear transparent structure present in the front of the eye. It allows rays of light to pass through it to reach the crystalline lens.
Microscopically, the cornea has 5 layers, Epithelium, Bowman’s membrane, Stroma, Descemet’s membrane, endothelium. The innermost layer, that is the endothelium, has the function of pumping water out of the remaining layers. The cornea is special in many ways. It has no blood supply except the peripheral 1-2 mm rim. This, in addition to the endothelial pump allows it to maintain its transparency. This also provides the cornea Immune privilege, which partially protects a corneal transplant from rejection. Secondly, only cells of the corneal epithelium can regenerate. The rest of the layers do not regenerate but lead to formation of opaque scars. The endothelial cells, however, can up-to a certain extent, expand and compensate for the function of other lost endothelial cells.
Common corneal disorders include conditions such as Corneal Ulcers, Keratoconus, Corneal Dystrophies and degenerations, Trauma, Ocular surface conditions such as Steven Johnson Syndrome, Severe Dry eye disease, Ocular Cicatricial Pemphigoid, etc.. Medical management is effective in infections, dry eye diseases and early cases of corneal decompensation. Most other disorders require surgical treatment in the form of transplant procedure.
Traditionally, corneal transplantation has been performed as a full thickness procedure, replacing all the layers of the cornea irrespective of the primary disease. However, recent advances in surgical procedures now permit us to transplant selectively the faulty layers, based on the primary layer affected. At Asian eye institute and laser centre in Mumbai , all the latest types of surgeries are performed ensuring that the patient receives the best care he deserves at the appropriate cost.
Full thickness Corneal Transplant:
This involves replacing the entire thickness of the cornea with a donor cornea and fixing it with 16 sutures. Postoperatively, steroid drops are required on a life long basis to prevent rejection. The sutures are gradually removed. Glasses may be required for clear vision until all the sutures have been removed or have degenerated.
Deep Anterior Lamellar keratoplasty:
This involves removal of only the anterior most layers of the cornea, carefully retaining the normally functional endothelium. Approximately 16 sutures are required to secure the graft. Preserving the endothelium eliminates the chance of an endothelial rejection and reduces the need for post operative steroids.
Descemets stripping endothelial keratoplasty
This involves selectively replacing the faulty endothelium. Only 2/3 sutures are sufficient to secure the graft. The procedure significantly reduces the chances of rejection as compared to a full thickness graft. Also visual recovery is much quicker requiring lesser change of glasses.