Lasers and interventions for corneal diseases

by

Cornea Transplant: Intervention, Artificial Cornea and New Treatments

Corneal transplant is the replacement of the patient’s cornea with a new cornea from a human or artificial donor. Thanks to important innovations, cornea transplant is now a safe and effective operation . Often the entire cornea is no longer replaced, as was done in the past, but only a small part and it is then called a lamellar cornea transplant . Lamellar cornea transplant is divided into anterior or posterior depending on whether the anterior or posterior part of the cornea is replaced. There are different types of cornea transplants today:

The artificial cornea and the lamellar cornea transplant allow you to regain your sight very quickly and with fewer complications than in the past. Whole cornea transplant (perforating keratoplasty) is performed today in increasingly limited cases in favor of the most modern lamellar cornea transplant techniques.

Cornea transplant or perforating keratoplasty

Full-thickness corneal transplantation (penetrating keratoplasty) is the first historically performed corneal transplantation technique. It is the most widespread technique in the world of cornea transplant. It consists of replacing the central portion of the damaged cornea with a transparent and healthy donor cornea. The part of the cornea that is removed from the patient and the new cornea that is transplanted are best made the same size: usually between 8 mm and 9 mm in diameter. In the past, a donor cornea larger than 0.50 mm in diameter was used and this could lead to greater myopia and astigmatism after surgery. Unfortunately, this practice is still widespread today, despite the possibility of avoiding the onset of post-transplant vision defects. Cornea transplant can be performed with the Femtosecond Laser . In this case the cornea of the donor and that of the patient who receives it are prepared with the Laser. We know today that laser-assisted corneal transplantation and that performed with modern corneal drills give the same results. The cornea used for corneal transplant is provided by the Cornea Bank. Cornea Banks are organized on a regional basis in Italy (in Lombardy for example there are two: Monza and Pavia; in Veneto one, the Mestre Eye Bank), they provide for the collection of corneas from donors who have expressed their consent and distribute them within the region they belong to. Once removed, the corneas are examined and placed in culture medium. Those suitable for transplant are processed and provided to surgeons following a series of rigorous criteria. Dr Badalà performs corneal transplants using tissues from the Banca della Cornea del Veneto (Mestre) and the Banca della Cornea di Monza. Today it is best to perform the transplant only in specialized corneal transplant centers where the lamellar transplant is also performed which, if possible, is preferable. Dr. Badalà performs corneal transplants in Milan and Catania and collaborates with the most important corneal transplant centers. Once prepared, the donor cornea is sutured by the eye surgeon to the patient’s cornea . There are several ways to suture the patient’s and the donor’s cornea. Expert management of the suture allows for rapid recovery of vision. The type of suture usually used is a 10/0 Nylon, which is the smallest suture in medicine. Anesthesia for cornea transplant can be local or general. General anesthesia is usually preferred if the patient is young and easily emotional, otherwise local anesthesia, through an injection of anesthetic around the eye, allows to obtain an excellent result.

Cornea Transplant: After Surgery

The patient who received a cornea transplant leaves the operating room with a protective patch on his eye . Usually Dr Badalà removes the bandage a few hours after the operation or at the latest on the first day after the operation. Already in the first days after the transplant, vision is usually better than before the operation, however for complete visual recovery it is necessary to wait 10-12 months from the date of the corneal transplant. Vision gradually improves until the suture is removed. It is advisable to carry out checks after corneal transplant every 30 days for the first 4 months and then every 60 days up to a year after surgery. Around this time the suture is usually removed. Therapy after corneal transplant The patient undergoing corneal transplant must undergo a therapy based on antibiotics in eye drops or ointments for about one or two weeks and a therapy based on cortisone in eye drops or ointments for about a year, even if with increasingly reduced frequency. In the first months after the transplant it is good practice to often use artificial tears, as the transplanted cornea has no sensitivity in the first months and tends to become dry. The correct use of artificial tears allows for a speedy recovery usually after 4-6 months. In 10-15% of cases rejection can occur , which in most cases can be treated pharmacologically, without having to repeat a transplant. The risk of rejection of the corneal transplant is always present throughout the patient’s life, so when faced with a red eye after a corneal transplant, a check-up by the ophthalmologist is always urgent . Activities to do and avoid after corneal transplant It is of fundamental importance not to rub the corneal transplanted eye and avoid trauma of any kind. For this reason, immediately after the operation, the patient must always have his eye protected. Dr. Badalà usually recommends glasses during the day and a protective eyecup during sleep at night. Work activity can usually be resumed after about two weeks, although the timing of return to work is affected by various subjective variables. It is good practice to resume sporting activity approximately one month after the transplant . Obviously it depends on the type of sporting activity: contact sports (football, basketball, volleyball) must be absolutely avoided for a long period and their practice must be discussed with the treating ophthalmologist. Swimming and the gym can be resumed with some peace of mind after a month, subject to the advice of a specialist. Eye makeup is best avoided for a couple of months . In any case, particular attention must always be paid to the make-up removal phase, to avoid damaging the eye with rubbing maneuvers that are sometimes necessary to remove make-up. It is always essential to discuss these aspects with the eye surgeon who performed the transplant.

Artificial Cornea or Boston Keratoprosthesis

The artificial cornea is the latest frontier for the treatment of corneal diseases . There are different types: the most used is the Boston artificial cornea (keratoprosthesis) . An artificial cornea model still in the testing phase is synthesized in the laboratory but improvements in the solidity of the materials are still awaited. In the past, the artificial cornea or keratoprosthesis has had great success, modified by Professor Falcinelli of Rome who perfected a technique that bears his name, the Falcinelli keratoprosthesis in which an artificial cornea is constructed by extracting a patient’s tooth which then, after having been modified, will be implanted in the eye. The Boston artificial cornea (keratoprosthesis) is the latest generation of keratoprostheses and the most used in the world today. It is made of latest generation plastic materials and titanium and integrates well into the human eye. The main indications of the Boston artificial cornea are:

  • Rejection of two or more corneal transplants
  • Neovascularization of the cornea as a consequence, for example, of an infection, caustication by chemical agents or trauma
  • Corneal stem cell deficiency
  • Caustication by chemical agents

The risks of the Boston artificial cornea are much reduced compared to other types of artificial cornea however the risk of infection persists, for this reason the use of antibiotic eye drops is recommended indefinitely. The Dr. Badalà was the first Italian surgeon to implant the Boston artificial cornea and the one, to date, with the greatest experience having implanted over 70 in the last 10 years.

The main advantage of the Boston artificial cornea is that even in the presence of rejection the artificial cornea remains transparent. However, patients operated with this technique must wear a contact lens and instill eye drops permanently. The Dr. Badalà has held several courses on artificial corneal transplantation in Boston at major international conferences (see news section of the site). The details of the first artificial cornea operation in Italy are summarized in the article published in 2008 opposite

Anterior Lamellar Cornea Transplant – DALK

The latest development in corneal transplantation for keratoconus is the anterior lamellar corneal transplantation (DALK). Anterior lamellar cornea transplant ( DALK) consists of replacing the anterior portion of the corneal tissue (stroma). This type of cornea transplant is indicated in cases of:

  • keratoconus (for corneas without damage to Descemet’s membrane)
  • Superficial corneal scarring following trauma or infection.

Anterior lamellar cornea transplant can be performed with different techniques. The most innovative anterior lamellar cornea transplant technique is the DALK big bubble technique. With great technical expertise, the various layers of the cornea are manually separated. Other techniques involve the use of a microkeratome or an excimer or femtosecond laser. All techniques aim to remove the stroma up to the endothelium in order to create an interface, on which to suture the transplanted flap, as homogeneous as possible to guarantee better post-operative visual quality. The advantage of the lamellar cornea transplant (DALK) compared to the traditional cornea transplant is that the chances of corneal rejection are lower as the portion of transplanted tissue is smaller. The donor corneal flap is sutured in the same way as a full-thickness corneal transplant. Another advantage of anterior lamellar cornea transplant is that suture removal can be done earlier with faster visual recovery then compared to conventional cornea transplant. This is particularly important in patients with keratoconus in whom anterior lamellar cornea transplant is performed, because they are young and active people. Dr. Badala’ performs anterior lamellar cornea transplant with the DALK technique for the treatment of keratoconus in Milan and Catania and holds courses on this innovative cornea transplant technique at major international conferences.

Corneal Endothelium Transplant – DSAEK or DMEK

Corneal endothelial transplantation is becoming the most popular type of corneal transplant. It is performed in cases of corneal edema due to guttate cornea or bullous keratopathy. In endothelial transplantation the entire cornea is no longer replaced but only the damaged internal layer (the endothelium) .

The advantage of endothelial transplantation is much faster visual recovery compared to conventional corneal transplantation. The most common corneal endothelial transplant technique is DSAEK. It consists of removing only the endothelium of the patient’s cornea and replacing it with a healthy donor endothelium. The thin internal layer of the cornea is removed, replaced with a new layer and then an air bubble is injected inside the eye to make the new endothelium adhere to the patient’s cornea. The advantages of endothelial transplantation (DSAEK) compared to conventional transplantation are numerous:

  • convalescence after endothelial transplantation is very rapid, generally three months after surgery the patient has complete visual recovery;
  • Only two or three stitches are used , thus eliminating all the complications related to the multiple sutures of traditional corneal transplantation (including high astigmatisms and erosions or infections of the corneal surface).
  • The risk of endothelium transplant rejection is lower than that of a traditional corneal transplant.

A new endothelial transplant method is DMEK (Descemet Membrane Endothelial Keratoplasty) in which the portion of transplanted tissue is even thinner, and visual recovery is theoretically even faster. Dr. Badalà performs this type of endothelial transplant in cases of bullous keratopathy and guttate cornea in Milan and Catania.

Corneal Stem Cell Transplant

Stem cell transplantation now offers the possibility of treating some corneal diseases . In the future, retinal diseases will probably also be included , however in this case research is still at an early stage.

Who can do it?

There are various subjects who can benefit from a corneal stem cell transplant : people whose corneal epithelium has been damaged by

  • burns from acids , lime, or other chemical agents
  • infections ,
  • congenital diseases such as aniridia ( congenital disease for which one is born without an iris);
  • autoimmune diseases such as Steven Johnson syndrome or ocular pemphigoid,
  • abuse of contact lenses.

Corneal stem cells are located in the limbus, they are arranged in a crown between the cornea (the transparent part of the eye) and sclera (the white part of the eye). When the conjunctival epithelium that lines the white part of the eye is damaged, it covers the entire cornea which thus loses its transparency and vision is compromised. If the problem is in only one eye, it is possible to transplant corneal stem cells from the healthy eye to the diseased eye. Here, within a month and a half the stem cells reproduce and the cornea no longer becomes opaque ( autologous transplant ). If the problem is in both eyes , it will be necessary to resort to donation from a close relative (parent or sibling), at least 50% identical, or from a cadaver, using anti-rejection treatments ( heterologous transplant ). A great opportunity in the most serious cases is the possibility of cultivating corneal stem cells in the laboratory and so even in the presence of a few healthy cells it is possible to obtain a good result through autologous transplant (i.e. cells from the same patient). most cases must be completed by corneal transplant to also replace the damaged corneal stroma. The alternative for rapid visual rehabilitation in many of these cases is the Boston artificial cornea transplant (keratoprosthesis) . These operations are performed only in specialized corneal transplant centers. Dr Badalà performs them in Milan and Catania.