Corneal transplantation refers to the treatment of cloudy cornea, which is also an effective operation to cure blindness and restore vision. It belongs to organ and tissue transplantation.
Corneal transplantation materials have gone through more than a century from the use of inactivated transplantation materials to xenotransplantation and then to artificial cornea materials and biological materials. From the first successful penetrating keratoplasty in 1905 to now, it has experienced a qualitative leap. From the use of drugs to prevent and treat graft immune rejection, to the use of fine suture materials, the patient's inflammation and discomfort have been greatly reduced.
There are many types of donors for corneal transplantation, each with its own characteristics. Today we will introduce the current situation and new progress of various corneal transplantation donor materials.
Autologous corneal graft material
The earliest autologous corneal transplantation was to replace the diseased corneal tissue with the patient's own healthy corneal tissue, or use the cornea of the healthy eye as a graft to restore his vision.
The first case of autologous keratoplasty in human history occurred in 1908 when Plange removed turbid corneal tissue for lime burn patients and used another blind eye (intact and transparent cornea) as a donor for penetrating keratoplasty. Then in 1912, Mora successfully transplanted the same cornea.
The characteristic of autologous corneal transplantation is that the graft material comes from the patient itself, and there is no graft rejection.
With the maturity of corneal transplantation technology and the improvement of limbal stem cell theory, since Ken first performed limbal stem cell transplantation in 1989, especially in the past decade, many scholars have devoted themselves to the cultivation and transplantation of autologous limbal stem cells, making limbal stem cell transplantation develop to a certain extent in clinical practice.
At present, autologous limbal stem cell transplantation is still in the experimental stage, and its long-term efficacy needs further clinical observation. How to control the differentiation of stem cells and the influence of cytokines on it need further research.
Corneal allograft
The corneal allograft materials are mostly from the eye bank.
In 1931, Filatov, a Soviet corneal transplant specialist, used the corneas of human cadavers preserved at 2-4 ° as donors for the first time to perform corneal allograft transplantation for patients with keratopathy, which opened the door to the application of cadaveric corneas and laid a foundation for the establishment of an eye bank.
In the past, scholars focused on the collection and selection of transplant materials, and reached empirical conclusions that the ideal donor is usually an adult who died suddenly under the age of 60. However, the corneal donor research group conducted a prospective study on 1090 subjects after corneal transplantation, and finally concluded that donor materials under 75 years old are suitable for corneal transplantation, and have the same quality of post transplantation effects.
In recent years, posterior/deep lamellar corneal endothelium transplantation has been developed, which is used to treat corneal endothelium decompensation caused by various reasons, such as Fuchs corneal endothelium dystrophy, intraocular lens (IOL) complicated with bullous keratopathy and aphasia.
It has two surgical methods, one is pedicled posterior/deep corneal endothelial lamellar transplantation; The second is posterior/deep lamellar corneal endothelium transplantation through corneoscleral border tunnel. Compared with penetrating keratoplasty, the advantages of posterior/deep lamellar corneal endothelium transplantation are: short operation time, small incision, seamless line, closed posterior lamellar corneal endothelium transplantation reduces the risk of intraocular content prolapse during the operation, less high astigmatism after the operation, fast vision recovery, reduced the number of follow-up visits due to selective suture removal, and eliminated corneal vascularization caused by suture factors, Only the presence of deep transplanted tissue can reduce the rejection of the host to the graft, and because the anterior and posterior lamellar incisions are not in the same position, the possibility of incision rupture is small. Moreover, this technology can make full use of the corneal tissue with tight sources. The posterior lamellar corneal tissue can select the corneal donor material that has undergone excimer laser surgery, even if the anterior layer has corneal scar, it can still be used.
Artificial cornea material
The research of artificial cornea has gone through two centuries. It was first proposed by French ophthalmologists in 1771. In 1871, Weber implanted a piece of crystal glass into the cornea of the patient, creating a new era of artificial cornea implantation.
According to the research status in the past 20 years, artificial cornea materials mainly consist of central optical column and peripheral stent. Three materials commonly used for optical lens columns are polymethyl methacrylate (PMMA), silicon gel and endophene ester; The commonly used peripheral stents are expanded polytetrafluoroethylene, fluorocarbon polymer, hydroxyapatite, polyester, carbon fiber, titanium metal and biological materials.
Take the artificial cornea produced by our company as an example. Mihe artificial cornea is composed of lens column and stent. The mirror column is made of polymethyl methacrylate. The stent is composed of titanium stent wing and polymethyl methacrylate stent seat.
Different from other artificial corneas, Mihm artificial cornea has a wide range of indications. It can be used by all patients with binocular corneal blindness who are difficult to succeed in corneal transplantation, such as those blinded by chemical injury, thermal burn, explosive injury, and severe autoimmune diseases.
In addition, Mihm artificial cornea is made of artificial materials without donor cornea, which is the only artificial cornea in the world without donor cornea implantation so far.
It is the key field of long-term research to improve the compatibility between cornea and tissue and reduce rejection and complications. The selection of materials and the development and application of new materials are the keys to improve the success rate of corneal transplantation. Therefore, it is very important to accelerate the R&D and application of new materials and technologies. Mihm Medical will also use its own technological advantages to benefit the vast number of corneal blindness patients!