Corneal transplant_corneal inlays
Corneal transplant / corneal inlays
“The cornea is a kind of transparent porthole in front of the color of the eye,” says Dr. François Majo. And it’s more than just a lens. Made mainly of collagen, water and cells, it is a complex whole, having a primordial role for the vision (read our article Indispensable horny). With age or because of trauma, burns (including chemical), various conditions or following an operation (see box), its transparency and curvatures can be altered. This leads to a decrease in visual acuity, or even the loss of vision. In these cases, a corneal transplant may be indicated.
“The corneal transplant can be done at any age, even at age 90,” says Dr. Majo. Sight makes it possible to establish and preserve the social bond, it is therefore essential to operate also older people who would otherwise lose their autonomy. ”
The main indications of corneal transplant
Corneal opacities are the third leading cause of blindness in the world after glaucoma (intraocular hypertonia) and cataracts (opacification of the lens).
The corneal transplants are indicated mainly during the following attacks:
Fuchs dystrophy and bullous dystrophies of the cornea (45% of cases): this degenerative disease causes premature aging of the cornea with a decrease in the number of endothelial cells lining the inner layer. In this case, the cornea is thickened by edema and the refractive index changes, leading to a loss of vision. In these cases, a corneal transplant provides good functional recovery.
Infectious keratitis (10 to 20% of cases): bacterial, viral (including herpes keratitis, 5%), parasitic or fungal infections of the cornea.
The keratoconus (40% of the indications) causes a gradual thinning of the cornea with a progressive deformation: the cornea takes the form of a cone. This disease can already manifest itself in adolescence. A transplant is performed if vision can no longer be improved with special glasses or contact lenses, or if the cornea becomes opaque. This happens most often around 25-35 years old. The transplant can restore 100% vision by wearing contact lenses.
Failures of grafts: in particular rejection of the graft.
Renewal of the graft: after 10, 30 or even 40 years depending on the case, when the graft has aged, it must be replaced.
Post-traumatic scars: for example, following an eye operation, an accident at work, a domestic accident (gardening, DIY, leisure), an assault, etc.
Reduced risk of rejection
The high rate of success of these transplants lies in the fact that they do not require tissue and blood compatibility between recipient and donor, as is the case for organ transplants. Because corneal tissue is not vascularized (ie, blood vessel-free), the risk of rejection is much lower than after transplanting an organ such as the heart or kidney.
However, the recipient will have to take anti-rejection treatment (steroids or cyclosporine), in the form of eye drops during the two years following the operation. In addition, all potential organ donors receive blood tests for infections they may transmit to the recipient (hepatitis B, hepatitis C, HIV, etc.).
Nevertheless, there remains a minimal risk of infection, due in particular to the appearance of new fungi, bacteria or viruses still unknown and therefore not detectable with the usual tests.
In recent years, a new surgical correction technique for presbyopia has emerged, and may be an interesting option in some cases, especially for patients with no distant vision correction.
This technique consists in implanting, in the thickness of the cornea of the Inlays, placed in the center of the cornea, after cutting of a lamella, similar to the corneal lamella cut in Lasik, but generally thicker.
All Inlays techniques are intended to be performed on one eye and we always choose the non-dominant eye in far vision. It is not necessary to risk disturbing the distant vision of the dominant eye. It is therefore, as for the Intracor technique, surgery intended to remain unilateral.
– Implants with clean optical power, intended to cause a bulge of the central cornea, such as the Flexifue MicrolensTM implant. This is a transparent implant with a diameter of 3.2 mm and a thickness of 15 μ, which, placed in the center of the cornea, induces a central bulge conducive to near vision, ideally achieving multifocal the operated eye.
These techniques obviously require a little more distance to appreciate the effectiveness and safety, but they represent a new therapeutic alternative in the surgery of presbyopia.