Corneal transplantation is the most effective way to restore vision for patients blinded by keratopathy. In order to avoid surgical failure, we should pay attention to the common causes of surgical failure, such as postoperative immune rejection and endothelial failure, as well as the impact of ocular surface structure destruction and tear film homeostasis loss on the graft.
Almost all patients after corneal transplantation will have dry eye symptoms, and some of them will develop into persistent chronic ocular surface dysfunction. Through clinical observation, researchers found that patients after corneal transplantation had problems such as decreased secretion of ju fluid and unstable tear film for a long time.
In addition to the symptoms such as dryness and foreign body sensation, dry eyes after surgery may also cause superficial punctate keratitis and repeated stripping of corneal epithelium, and the long-term inflammatory reaction of the eye may also cause damage to corneal endothelial cells, thus affecting visual function and even causing surgery failure. Therefore, we must fully realize the harm of dry eye after keratoplasty and how to treat and prevent it.
Postoperative dry eye treatment
The pathogenesis of dry eye caused by corneal transplantation is different from that of common dry eye. It is mainly due to the loss of tear film stability caused by corneal nerve injury and ocular surface structure destruction, which belongs to mixed dry eye.
Most patients have dry eyes that do not last long after surgery and can relieve themselves, but some patients will develop into dry eyes that are chronic or even affect the survival of the graft. Therefore, the treatment principle for this kind of dry eyes should be based on the pathogenesis, early detection and early treatment.
Tear Replacement Therapy
At present, artificial tears are mainly used in tear replacement therapy. Because of its properties similar to human tears, it is easy to be compatible with intraocular tissues. Moisten the eye surface to form a smooth and regular protective film, reduce corneal epithelial cell pressure and tear osmotic pressure after corneal transplantation, and improve tear film stability. However, the current artificial tears are mainly used to replace the water layer of tears, lack of lipid components and mucin in tear film, and have no definite anti-inflammatory and neurotrophic effects. Combined with its advantages of less eye irritation and less adverse reactions, it is considered that artificial tears are more suitable as the basic drug for dry eyes after corneal transplantation.
The composition and physical and chemical properties of autologous serum and normal tear are similar. It is rich in a variety of cell growth factors, such as epidermal growth factor (TGF) transforming growth factor, which can promote cell proliferation, differentiation and maturation, and is conducive to the repair of epithelial damage. At the same time, autologous serum also contains various proteins, amino acids, peptides and other substances, which not only provide sufficient nutrition for the growth of corneal epithelium, but also can improve the tear film status, lubricate and protect the cornea. Lysozyme, complement and other components contained in the serum can effectively inhibit the growth of bacteria and enhance the anti infection ability of the eye surface.
Anti inflammatory treatment
After corneal transplantation, patients often have persistent inflammatory reaction on the ocular surface due to surgical injury and the decline of tear film stability.
Glucocorticoid can effectively inhibit the activation of T fine Qu and reduce the expression of inflammatory factors, and produce anti-inflammatory effects. The representative drugs of immunosuppressants are cyclosporine A and tacrolimus. Cyclosporine can inhibit the release of proinflammatory factors and promote the release of anti-inflammatory factors to interfere with T cell mediated inflammatory response, playing an effective anti-inflammatory role; The drug efficacy of tacrolimus is 10~100 times that of cyclosporine A, and the effect is better.
Neurotrophic therapy
In clinic, artificial tears, glucocorticoids and immunosuppressants are routinely used in most patients after corneal transplantation. However, many patients will still have dry eyes after surgery. According to the pathogenesis, it is speculated that it may be related to the incomplete repair of injured corneal nerves, which should be paid attention to.
At present, some studies have used neurotrophic factor in the treatment of dry eyes after excimer laser surgery, and found that it can effectively alleviate the symptoms of dry eyes by promoting the repair of injured nerves. Other studies have found that nerve growth factor can increase the number of goblet cells, increase tear secretion, and reduce the apoptosis of corneal epithelial cells. Therefore, nerve growth factor is expected to become an effective method of dry eye treatment after corneal transplantation.
Other treatments
Inappropriate use of eye drops is one of the causes of dry eyes after keratoplasty, and the ocular surface structure of patients after keratoplasty is very fragile. Therefore, the application of auxiliary treatment such as acupuncture, traditional Chinese medicine steaming, bandage mirror and other methods can reduce the ocular drug use and reduce the toxicity of eye drops.
In recent years, clinical studies have proved that acupuncture treatment can improve the excitability of neurotransmitters, effectively inhibit inflammatory reaction, and reduce cell apoptosis. Traditional Chinese medicine fumigation can promote the expansion of eye capillaries, improve blood circulation, provide sufficient nutrition for the repair of corneal injury, and also have an effective anti-inflammatory and analgesic effect, and regulate nerve conduction.
Patients with corneal transplantation often have eye abrasion, eye pain, photophobia, lacrimation and other symptoms after surgery, which are intolerable to patients, so they are unwilling to cooperate with treatment, affecting the healing of corneal epithelium after surgery. Bandage glasses can significantly reduce the above symptoms. At the same time, because the tear film of patients after surgery is unstable, the shearing force during blink is easy to damage the corneal epithelium that is just emerging, and corneal bandage glasses can play a very good role in protection. These methods may be difficult to treat dry eyes after keratoplasty alone, but their action mode is mild and less destructive, so they can be used as supplementary treatment.
Prevention of dry eye after operation
The prevention of dry eye after corneal transplantation should pay attention to the following points:
① The preoperative examination was improved, and patients with dry eyes were found before surgery. For suspicious people such as elderly women, long-term wearing of corneal contact lenses, long-term use of video terminals, etc., the tear secretion test and tear film rupture time measurement were routinely performed before surgery. Once dry eye is diagnosed, adequate treatment should be given in time to improve the ocular surface environment as much as possible before surgery.
② The operation should be gentle to reduce the damage of corneal nerves, goblet cells, facial gland and other structures. The graft and implant bed should be aligned as smoothly as possible, and necessary eye surface protection measures should be taken.
In a word, dry eyes after corneal transplantation are generally self limiting. With the repair of ocular surface damage and nerve regeneration, the unstable state of tear film will gradually recover, but attention should also be paid to the toxic effects of various eye drops after surgery.
At the same time, it is also very important to prevent the occurrence of dry eye. Sufficient tear function examination should be conducted before surgery to evaluate the possibility of dry eye after surgery, and effective intervention should be given before surgery. In order to avoid chronic persistent dry eye after surgery, which will cause epithelial defect of the graft and affect the survival of the graft, on the basis of artificial tears and anti-inflammatory treatment, attention should also be paid to the nutritional repair of nerves, and acupuncture, herbal fumigation and other treatment methods should be properly assisted.