**3.1 Differential diagnosis between keratitis caused by microbes**

There are a lot of reason for make microbial culture collection in all protocols to identify the type of microbial keratitis pre or post keratoplasty: Signs are similar in bacterial keratitis, exist mixed infections which required different treatments, there are several signs can help to make the differential diagnosis prior to the results of the microbiological findings, some of these are:


Table 1. Microbes finding on clinical pearls of keratitis complications associated with corneal infections after keratoplasty and common treatment.

The Complications After Keratoplasty 107

Fig. 2. Keratitis and posterior endophtalmitis infection caused by *Staphylococcus sp*.

Vancomicine, Moxifloxacine,

*Fusarium sp.* No Amphotericin B or Natamycin or

*Candida sp.* No Amphotericin B or Natamycin or

Table 2. Microbes finding on keratitis complications associated with corneal infections after

In the case of infection caused by *Acanthamoeba sp.*, propamidine isethionate 0.1% ophthalmic solution administrated concomitantly with neomycin-polymyxin B gramicidin ophthalmic solution has shown best results. Against neovascularization, another therapy

and the cooperation of the patient. It is important to act fast and certainly. The use of antibiotics like last generation fluoroquinolones is the best option and it is recognized around the world in the case of bacterial complications. With the fungus infections it is not easy, due that it is hard to have the microbiological findings on time. For these reason the

**ANTIMICOTICS AGENTS** 

silver sulfadiazine, intrastomal

Amphotericin B or Natamycin or silver sulfadiazine (against *Fusarium sp*.), intrastomal

silver sulfadiazine, intrastomal

No

No

variconazole.

variconazole.

variconazole.

(Courtesy: Ophthalmologist Emilio Méndez.M.D. Personal Atlas).

**TREATMENT** 

Ciprofloxacine

clarithromycin

Ciprofloxacin, Moxifloxacine, Gatifloxacine,

Vancomicine (against *Pseudomona sp*. )

clinical pearls are so important to choice the best therapy. These are the antibiotic therapies recommended for experts:

**MICROORGANISMS ANTIBIOTICS FOR** 

*Mycobacterium sp.* Amikacin,cefoxitin,

keratoplasty and common treatment.

*Staphylococcus sp. Streptococcus sp.* 

*Fusarium sp. +Pseudomona sp.* 

Some infections are caused by more than one microorganism of different species, some of the normal flora or anothers opportunistic microbes like different bacteria species and in even and rare cases fungi and bacteria. It has been reported more frequently in contact lens wearers in widespread use without improper lubrication, as in the case of Figure 1, a case reported by our research group, where the patient also had a cosmetic tattoo in her eyes. On these cases perhaps an alteration of the normal flora associated with corneal dehydration can contribute to the eye injury. Some cases of contamination should be detected early and obligatorily required to perform a microbial culture using PCR techniques to detect it in less time and be very cautious with antibiotic and steroid therapy in these special patients. Steroids may get worse the damage still unknown causes andantibacterial antibiotics do not work against fungi. The review of these protocols and prior detection signs is the key to the success of a good corneal transplant.

Fig. 1. Infection before keratoplasty caused by Mixed flora: Bacterial keratitis and *Aspergillus sp.*, six days evolution. (Delgado, Chile. 2008, Photograph Personal Album: Márquez & Durán).

In the microbial ocular infections, those with bacterial association respond in most cases if the lesson is peripherical, if the lesson is central and affects optical zone, are more likely to result finally in keratoplasty, perhaps the periphery limbal vessels contribute to improved immune performance, while in central corneal recovery is slower and microbial invasion penetrates more easily to the stroma. But in the case of fungal infections, those fungal cases are caused in most cases for vegetal origin, inappropriately use of contact lenses or unknown causes. In China, in a study performed from 2000 to 2008 with 899 patients, they found no recovery when the treatment was made combined conjunctiva or intracamerular fluconazol. (Shi et. al. 2010). By the other hand, therapy with silver sulfadiazine ointment, natamycin is a better prognosis in cases of microbial infections of fungal origin. Another authors include cyclosporine to prevent graft rejection beginning 2 weeks after penetrating keratoplasty (PKP) and avoid steroids (Xie et al., 2001). Steroids for unknown cause in the case of fungus and bacteria like *Pseudomona* are not a good choice for treatment and cannot be administrated for the security of the corneal integrity. More studies are required in a future for new options of immunossupressor against immunological mediator of inflammation. It is important to check any graft rejection, clarity of the graft, visual acuity, and surgical complications after surgery in all cases.

#### **3.2 Treatment of microbial infections after keratoplasty**

The successful treatment of microbial infections requires of the experience of an interdisciplinary team: corneal experts ophthalmologists, immunologists and microbiologists

Some infections are caused by more than one microorganism of different species, some of the normal flora or anothers opportunistic microbes like different bacteria species and in even and rare cases fungi and bacteria. It has been reported more frequently in contact lens wearers in widespread use without improper lubrication, as in the case of Figure 1, a case reported by our research group, where the patient also had a cosmetic tattoo in her eyes. On these cases perhaps an alteration of the normal flora associated with corneal dehydration can contribute to the eye injury. Some cases of contamination should be detected early and obligatorily required to perform a microbial culture using PCR techniques to detect it in less time and be very cautious with antibiotic and steroid therapy in these special patients. Steroids may get worse the damage still unknown causes andantibacterial antibiotics do not work against fungi. The review of these protocols and prior detection signs is the key to the

Fig. 1. Infection before keratoplasty caused by Mixed flora: Bacterial keratitis and *Aspergillus sp.*, six days evolution. (Delgado, Chile. 2008, Photograph Personal Album: Márquez &

In the microbial ocular infections, those with bacterial association respond in most cases if the lesson is peripherical, if the lesson is central and affects optical zone, are more likely to result finally in keratoplasty, perhaps the periphery limbal vessels contribute to improved immune performance, while in central corneal recovery is slower and microbial invasion penetrates more easily to the stroma. But in the case of fungal infections, those fungal cases are caused in most cases for vegetal origin, inappropriately use of contact lenses or unknown causes. In China, in a study performed from 2000 to 2008 with 899 patients, they found no recovery when the treatment was made combined conjunctiva or intracamerular fluconazol. (Shi et. al. 2010). By the other hand, therapy with silver sulfadiazine ointment, natamycin is a better prognosis in cases of microbial infections of fungal origin. Another authors include cyclosporine to prevent graft rejection beginning 2 weeks after penetrating keratoplasty (PKP) and avoid steroids (Xie et al., 2001). Steroids for unknown cause in the case of fungus and bacteria like *Pseudomona* are not a good choice for treatment and cannot be administrated for the security of the corneal integrity. More studies are required in a future for new options of immunossupressor against immunological mediator of inflammation. It is important to check any graft rejection, clarity of the graft, visual acuity,

The successful treatment of microbial infections requires of the experience of an interdisciplinary team: corneal experts ophthalmologists, immunologists and microbiologists

success of a good corneal transplant.

and surgical complications after surgery in all cases.

**3.2 Treatment of microbial infections after keratoplasty** 

Durán).

Fig. 2. Keratitis and posterior endophtalmitis infection caused by *Staphylococcus sp*. (Courtesy: Ophthalmologist Emilio Méndez.M.D. Personal Atlas).

and the cooperation of the patient. It is important to act fast and certainly. The use of antibiotics like last generation fluoroquinolones is the best option and it is recognized around the world in the case of bacterial complications. With the fungus infections it is not easy, due that it is hard to have the microbiological findings on time. For these reason the clinical pearls are so important to choice the best therapy.


These are the antibiotic therapies recommended for experts:

Table 2. Microbes finding on keratitis complications associated with corneal infections after keratoplasty and common treatment.

In the case of infection caused by *Acanthamoeba sp.*, propamidine isethionate 0.1% ophthalmic solution administrated concomitantly with neomycin-polymyxin B gramicidin ophthalmic solution has shown best results. Against neovascularization, another therapy

The Complications After Keratoplasty 109

asymptomatic or has minimal skin irritation. It is self-limiting and

• The first type is characterized by elevated epithelial rejection line that stains with fluorescein or rose bengal. Progresses rapidly in days to 2 weeks and may take the form of a ring concentric to the limbus, peripheral to the interface area and subsequently shrinks to the center. The line represents an area of destruction of donor

• The second type is characterized by the presence of subepithelial

by a haze peripheral full-thickness, limbal injection in a previously clear corneal button. Infiltration can be identified in the peripheral

(Khodadoust, 2008), which usually begins in a vascularized portion

mononuclear cells (white blood cells that appear at the vascularized edge of the recently transplanted cornea, if untreated, the line of white blood cells move across and damage the endothelial cells of the cornea. There may be a reaction of moderate to severe CA. The damaged endothelium cannot maintain adequate dehydration of the button and the swells in the posterior to the line, while before it is transparent. Another variant of endothelial rejection presents with diffuse keratic precipitates and anterior chamber reaction, stromal edema localized but not widespread and limbal injection.

endothelial surface over several days. It consists of mononuclear white cells damage the endothelium. This line is made up of

of the interface and progresses, if untreated, through the

infiltrates, which contain lymphocytes. They are similar in appearance to those produced by adenovirus. Can change shape,

Epithelial failure Occurs in two forms that respond to steroid use. The patient is

location and disappear by themselves. Stromal failure It is accompanied usually of endothelial rejection. It is characterized

Risk factors Vascularization on the base layers of the recipient corneal. It is the

History of previous rejection of any kind

Presence of epithelium in a donor transplant

Large and eccentric grafts

Bilateral Keratoplasty

transplantation

Age

Table 3. Types of corneal transplant failure

only factor whose relationship to the increased incidence of rejection has been demonstrated. It is believed to be due to loss of immune privilege of the cornea due to normal avascularity

Preservation transportation media and corneal tissue pre -

Association with atopic dermatitis, allergy and asthma

Incompatibility of HLA-A, HLA-B and ABO group

interface progresses centrally Endothelial failure A classic rejection presents with endothelial rejection line

does not change in the visual acuity (V.A.).

epithelium, which is covered by host epithelium.

has been used, topical bevacizumab, a humanized monoclonal antibody that recognizes and blocks vascular endothelial growth factor A (VEGF-A). VEGF-A is a chemical signal that stimulates the growth of new blood vessels (angiogenesis) in graft rejection (Saxena, 2009). The scientists reported successfully results in one case of graft rejection 6 months following penetrating keratoplasty (triple procedure) in the left eye. With the administration of topical bevacizumab (4 mg/4 mL) in a dose of one drop twice a day for 15 days, she improved her vision and this short topical bevacizumab therapy, may potentially offer a safer and more effective alternative in treating graft rejection after penetrating keratoplasty. The administration must be subconjunctival also, and it is in study for side effects.

## **3.3 Immunological findings after keratoplasty**

One of the major complications associated with corneal graft rejection post-keratoplasty associations are immune from the donor and recipient. The therapy with immunomodulators before and after treatment required an individual protocol like a great option to prevent such rejection. Corneal transplantation is a continuous release of antigens in the different corneal layers of specific immune response against the donor cornea. This rejection may occur soon after surgery or month and years later. The following table specifies the associated warning signs in case of rejection and to be taken into account in the post-operative:

Studies in animal models (mice) based on corneal transplantation have shown that the main mediators of the immune response implicated in cases of graft rejection are CD4 cells Th1, Th2, CD4+, CD25+ and recently and hypothesis that Th17 play a crucial role in allograft rejection (Cunnusamy, 2010). Also, eosinophils secrete an array of cytotoxic granule cationic proteins such as major basic protein (MBP), eosinophil cationic protein (ECP), eosinophile peroxidase (EPO), eosinophil-derived neurotoxin (EDN) which are capable of inducing tissue damage and dysfunction (Gleich et al, 1993) and after this findings new chemical mediators are involved in this toxicity like eotaxin, a chemokine that attracts eosinophils to bind to its specific receptor, could induce the proliferation of fibroblasts, leading to the excretion of collagen. Fibroblasts also secrete eotaxin when stimulated by IL-4 and tumor necrosis factor (TNF) ( Kumagai et al, 2005). Additionally, one might think in the research based on inhibition of those toxins for therapy pre and post-keratoplasty in a future to minimize their toxic effects, which ones contribute to graft rejection. Some like the studies on mices in recent years, which are trying to use IFN-γ for inhibit eotaxin expression at both: protein and mRNA levels, in cultured human corneal fibroblasts. This effect of IFN-γ may contribute to the inhibition of eosinophil infiltration into the cornea. Exogenous IFN-γ thus represents a potential new therapeutic agent for the treatment of corneal disorders associated with inflammatory ocular diseases such as vernal keratoconjunctivitis.(Fukuda et al. 2002). Some patients present immunological events of rejection after years of POP, perhaps to systemic immunological complications that must be studied in each case with immunological analysis.


has been used, topical bevacizumab, a humanized monoclonal antibody that recognizes and blocks vascular endothelial growth factor A (VEGF-A). VEGF-A is a chemical signal that stimulates the growth of new blood vessels (angiogenesis) in graft rejection (Saxena, 2009). The scientists reported successfully results in one case of graft rejection 6 months following penetrating keratoplasty (triple procedure) in the left eye. With the administration of topical bevacizumab (4 mg/4 mL) in a dose of one drop twice a day for 15 days, she improved her vision and this short topical bevacizumab therapy, may potentially offer a safer and more effective alternative in treating graft rejection after penetrating keratoplasty. The

One of the major complications associated with corneal graft rejection post-keratoplasty associations are immune from the donor and recipient. The therapy with immunomodulators before and after treatment required an individual protocol like a great option to prevent such rejection. Corneal transplantation is a continuous release of antigens in the different corneal layers of specific immune response against the donor cornea. This rejection may occur soon after surgery or month and years later. The following table specifies the associated warning

Studies in animal models (mice) based on corneal transplantation have shown that the main mediators of the immune response implicated in cases of graft rejection are CD4 cells Th1, Th2, CD4+, CD25+ and recently and hypothesis that Th17 play a crucial role in allograft rejection (Cunnusamy, 2010). Also, eosinophils secrete an array of cytotoxic granule cationic proteins such as major basic protein (MBP), eosinophil cationic protein (ECP), eosinophile peroxidase (EPO), eosinophil-derived neurotoxin (EDN) which are capable of inducing tissue damage and dysfunction (Gleich et al, 1993) and after this findings new chemical mediators are involved in this toxicity like eotaxin, a chemokine that attracts eosinophils to bind to its specific receptor, could induce the proliferation of fibroblasts, leading to the excretion of collagen. Fibroblasts also secrete eotaxin when stimulated by IL-4 and tumor necrosis factor (TNF) ( Kumagai et al, 2005). Additionally, one might think in the research based on inhibition of those toxins for therapy pre and post-keratoplasty in a future to minimize their toxic effects, which ones contribute to graft rejection. Some like the studies on mices in recent years, which are trying to use IFN-γ for inhibit eotaxin expression at both: protein and mRNA levels, in cultured human corneal fibroblasts. This effect of IFN-γ may contribute to the inhibition of eosinophil infiltration into the cornea. Exogenous IFN-γ thus represents a potential new therapeutic agent for the treatment of corneal disorders associated with inflammatory ocular diseases such as vernal keratoconjunctivitis.(Fukuda et al. 2002). Some patients present immunological events of rejection after years of POP, perhaps to systemic immunological complications that must be studied in each case with

**PRIMARY FAILURE LATE FAILURE** 

transparency during the firsts

Graft failure after months or years

Gradual diffuse edema, increase corneal infiltrates, corneal

after postoperatory

vascularization

administration must be subconjunctival also, and it is in study for side effects.

signs in case of rejection and to be taken into account in the post-operative:

**3.3 Immunological findings after keratoplasty** 

immunological analysis.

Time of occurrence Graft failure after first days of postoperatory

weeks

Signs Edema after surgery, low

**TYPE OF FAILURE OF THE IMPLANT** 


Table 3. Types of corneal transplant failure

The Complications After Keratoplasty 111

endothelium and the insertion of a posterior donor button size similar through a limbal incision mm-9. Later, Melles et al. then doubled the donor graft that could be inserted through an incision of 5 mm. Another technique used to simplify the procedure was published by Dr. Goroyov, using a microkeratome to harvest the donor graft, a variation known as Descemet's endothelial keratoplasty automated extraction (DSAEK). Besides reducing the technical difficulty of the general procedure, descemetorhexis and microkeratome donor dissection was also softer surface receptor and donor, resulting in more satisfactory visual results. In 2006, Melles al. et al reported a success with a new variant called Descemet membrane endothelial keratoplasty (DMEK) involved in transplanting endothelium naked DM - a specific disease true form of keratoplasty with

In 2008, Dr. Pavel Studeny showed a variation of this technique at the American Academy of Ophthalmology annual meeting 2008, which formed a "huge bubble" of air to separate the center of 6 mm or less of the donor, separating the posterior stroma by manual lamellar dissection, removed the stroma during the great bubble and marked central tissue from a donor with the appropriate diameter to create a graft that was naked and central DM endothelium with stroma attached outer edge. This configuration allows easier handling and graft insertion or DSAEK/DMEK anyone. He recently had a variation of this technique called automated keratoplasty endothelial Descemet membrane (DMAEK), in which the donor tissue is first dissected with a microkeratome as DSAEK, a large central bubble is formed, the overlying stroma is removed large bubble, and the fabric is pierced with a drill. All those surgical techniques among others, contribute to reduce the inflammatory response by chemical mediators of inflammation reducing the reject of the implant and are so important for future immunological research and found a long term protocol and also epidemiological studies between those techniques and the relationship with the receptor immunological reject. But it must take in mind each patient's medical history, previous history of atopic dermatitis, systemic and ocular allergies, several dry eye and systemic associations such as diabetes, hypertension and especially those of an autoimmune rheumatoid arthritis, atopic dermatitis, among others to make a very good rating diagnosis before graft itself to the corneal donor. New alternatives based on artificial biopolymers are been introduced in recent researches, and it is mainly important to study the biocompatibility and immune response of these new technologies with the human ocular

Another new technique to performance keratoplasty is the femtosecond Laser-Assisted Lamellar Keratoplasty, which reduce intraoperative complications, additionally, optimizes postoperative refraction, allows faster visual rehabilitation, and decreases the risk of graft rejection and astigmatism, this technique permits create vertical and lamellar corneal incisions with a variety of shapes and angulations at a precise depth. Combining the advantages of lamellar keratoplasty with the surgical precision of a femtosecond laser enables us new surgical options. Femtosecond laser-assisted lamellar keratoplasty techniques include femtosecond laser-assisted anterior lamellar keratoplasty (FALK), femtosecond laser-assisted deep anterior lamellar keratoplasty (FDALK), and femtosecond laser-assisted endothelial keratoplasty (FLEK), (Yoo,S,Hurmeric V, 2011). The authors recommend performed in patients with deep stromal scarring, keratoconus and ectasia. Recent research led by scientists from Stanford University with a technique called advance Dolhman-Doane, which consists of a core of plastic biopolymer, transparent and tough, which is surrounded with human tissue and could be an alternative in countries where the corneal donation is not as accequible. For attachment to the rest of the globe, further

minimal trauma.

tissue.

Fig. 3. Keratitis infiltrates post-keratoplasty after 13 year of postoperatory of the keratoplasty. (Cortesy: Mayra Cáceres O.D.)

Another chemical mediator of immune response (Awadi, 2011) are metalloproteinases, collagenase, stomelysin and gelatinase. These matrix of metalloproteinases are inhibited by specific endogenous tissue inhibitors of metalloproteinases (TIMP1, TIMP2, TIMP3, TIMP4), like batimastat and marimastat. Modulation of metalloproteinase activity may thus help to model and minimize scarring such as that occurring in ketatoconus or after traumatic or surgical injury to the cornea (See Chapter Modeling of corneal healing and corneal inflammatory response). Those findings will be so useful to performer better protocols for receptors and immunological exam before and after surgery.

Recent research on bovine serum- free corneal cell and wounded organ cultures were developed with a range of concentrations of TGF- TGF-β1, -β2, and -β3; IL-10; and neutralizing human monoclonal antibodies (mAbs) against TGF-β1 in order to watch the inhibition of TGF-β for reduce the myofibroblast differentiation and fibrosis in the cornea, this results may contribute in a future to determined the actions of distinct TGF-β isoforms and their inhibitors during early corneal wound healing is an essential step in guiding therapeutic intervention. The found that TGF- β1 delayed re-epithelization, increased repopulation of the stroma, increase proliferation and was the only isoform to promote myofibroblast differentiation. Aditionally, IL-10 promoted corneal re-epithelialization at low doses but inhibited this response at high doses. Stromal repopulation was prevented by all doses of IL-10. TGF-β2 or the anti-TGF-β2 mAb, CAT-152 had little effect on any repair parameter. Treatment with the anti-TGF-β1 accelerates corneal re-epithelialization but reduces cell repopulation of the stroma. The cytokines TGF-β3 and IL-10 have opposing actions to that of TGF-β1. (Carrington L. et al. 2006).

By the other hand, the evolution of new surgical techniques have been improving for keratoplasty, as well as treatment protocols and prevention of graft rejection, beginning with the removal of sutures to secure the graft, in 1956, using a posterior approach, first reported for Tillett, in 1998, Dr. Gerritt Melles et al. described posterior lamellar keratoplasty (PLK) technique that uses air instead of sutures, placement of the graft to the recipient cornea. Their technique required initial lamellar dissection of the donor and recipient cornea, excision of a 7.5 mm diameter recipient posterior stroma 7.0 button with attached

Fig. 3. Keratitis infiltrates post-keratoplasty after 13 year of postoperatory of the

Another chemical mediator of immune response (Awadi, 2011) are metalloproteinases, collagenase, stomelysin and gelatinase. These matrix of metalloproteinases are inhibited by specific endogenous tissue inhibitors of metalloproteinases (TIMP1, TIMP2, TIMP3, TIMP4), like batimastat and marimastat. Modulation of metalloproteinase activity may thus help to model and minimize scarring such as that occurring in ketatoconus or after traumatic or surgical injury to the cornea (See Chapter Modeling of corneal healing and corneal inflammatory response). Those findings will be so useful to performer better protocols for

Recent research on bovine serum- free corneal cell and wounded organ cultures were developed with a range of concentrations of TGF- TGF-β1, -β2, and -β3; IL-10; and neutralizing human monoclonal antibodies (mAbs) against TGF-β1 in order to watch the inhibition of TGF-β for reduce the myofibroblast differentiation and fibrosis in the cornea, this results may contribute in a future to determined the actions of distinct TGF-β isoforms and their inhibitors during early corneal wound healing is an essential step in guiding therapeutic intervention. The found that TGF- β1 delayed re-epithelization, increased repopulation of the stroma, increase proliferation and was the only isoform to promote myofibroblast differentiation. Aditionally, IL-10 promoted corneal re-epithelialization at low doses but inhibited this response at high doses. Stromal repopulation was prevented by all doses of IL-10. TGF-β2 or the anti-TGF-β2 mAb, CAT-152 had little effect on any repair parameter. Treatment with the anti-TGF-β1 accelerates corneal re-epithelialization but reduces cell repopulation of the stroma. The cytokines TGF-β3 and IL-10 have opposing

By the other hand, the evolution of new surgical techniques have been improving for keratoplasty, as well as treatment protocols and prevention of graft rejection, beginning with the removal of sutures to secure the graft, in 1956, using a posterior approach, first reported for Tillett, in 1998, Dr. Gerritt Melles et al. described posterior lamellar keratoplasty (PLK) technique that uses air instead of sutures, placement of the graft to the recipient cornea. Their technique required initial lamellar dissection of the donor and recipient cornea, excision of a 7.5 mm diameter recipient posterior stroma 7.0 button with attached

keratoplasty. (Cortesy: Mayra Cáceres O.D.)

receptors and immunological exam before and after surgery.

actions to that of TGF-β1. (Carrington L. et al. 2006).

endothelium and the insertion of a posterior donor button size similar through a limbal incision mm-9. Later, Melles et al. then doubled the donor graft that could be inserted through an incision of 5 mm. Another technique used to simplify the procedure was published by Dr. Goroyov, using a microkeratome to harvest the donor graft, a variation known as Descemet's endothelial keratoplasty automated extraction (DSAEK). Besides reducing the technical difficulty of the general procedure, descemetorhexis and microkeratome donor dissection was also softer surface receptor and donor, resulting in more satisfactory visual results. In 2006, Melles al. et al reported a success with a new variant called Descemet membrane endothelial keratoplasty (DMEK) involved in transplanting endothelium naked DM - a specific disease true form of keratoplasty with minimal trauma.

In 2008, Dr. Pavel Studeny showed a variation of this technique at the American Academy of Ophthalmology annual meeting 2008, which formed a "huge bubble" of air to separate the center of 6 mm or less of the donor, separating the posterior stroma by manual lamellar dissection, removed the stroma during the great bubble and marked central tissue from a donor with the appropriate diameter to create a graft that was naked and central DM endothelium with stroma attached outer edge. This configuration allows easier handling and graft insertion or DSAEK/DMEK anyone. He recently had a variation of this technique called automated keratoplasty endothelial Descemet membrane (DMAEK), in which the donor tissue is first dissected with a microkeratome as DSAEK, a large central bubble is formed, the overlying stroma is removed large bubble, and the fabric is pierced with a drill. All those surgical techniques among others, contribute to reduce the inflammatory response by chemical mediators of inflammation reducing the reject of the implant and are so important for future immunological research and found a long term protocol and also epidemiological studies between those techniques and the relationship with the receptor immunological reject. But it must take in mind each patient's medical history, previous history of atopic dermatitis, systemic and ocular allergies, several dry eye and systemic associations such as diabetes, hypertension and especially those of an autoimmune rheumatoid arthritis, atopic dermatitis, among others to make a very good rating diagnosis before graft itself to the corneal donor. New alternatives based on artificial biopolymers are been introduced in recent researches, and it is mainly important to study the biocompatibility and immune response of these new technologies with the human ocular tissue.

Another new technique to performance keratoplasty is the femtosecond Laser-Assisted Lamellar Keratoplasty, which reduce intraoperative complications, additionally, optimizes postoperative refraction, allows faster visual rehabilitation, and decreases the risk of graft rejection and astigmatism, this technique permits create vertical and lamellar corneal incisions with a variety of shapes and angulations at a precise depth. Combining the advantages of lamellar keratoplasty with the surgical precision of a femtosecond laser enables us new surgical options. Femtosecond laser-assisted lamellar keratoplasty techniques include femtosecond laser-assisted anterior lamellar keratoplasty (FALK), femtosecond laser-assisted deep anterior lamellar keratoplasty (FDALK), and femtosecond laser-assisted endothelial keratoplasty (FLEK), (Yoo,S,Hurmeric V, 2011). The authors recommend performed in patients with deep stromal scarring, keratoconus and ectasia.

Recent research led by scientists from Stanford University with a technique called advance Dolhman-Doane, which consists of a core of plastic biopolymer, transparent and tough, which is surrounded with human tissue and could be an alternative in countries where the corneal donation is not as accequible. For attachment to the rest of the globe, further

The Complications After Keratoplasty 113

to take into account to prevent complications: compression or deformation of the globe, ocular tone down a narrow cleft interpalpebral a misplaced speculum, a thread tension of the upper rectum or scleral support ring misplaced which can distort the cornea during the

During surgery it is necessary to have a team that includes appropriate microsurgical instruments apart from the ideal, a proper system illumination and a keratoscope surgical microscope. Postoperatively, many factors can also influence the final astigmatism, age, existing disease into the receiver, local and systemic steroid use local time each suture is kept before being withdrawn, leaving them to favor reports longer. It should be up on the controls to show signs of possible rejection, early withdrawal of sutures, traumatic or spontaneous ectasia, epithelial problems, and secondary infection. We must decide, first, the diameter of the graft and the window. Often it will be a compromise between including all opaque or affected area on one side and try not to reach the peripheral vascularized limb or

The suture is probably the main factor that may influence the prevention or induction of astigmatism QP. It is important to correctly position each and every one of the points because one of them misplaced can induce astigmatism may not be discovered until the sutures are removed and can be difficult to correct with a secondary procedure. 10-0 nylon monofilament is still the reference material for the final suture button, but in reality is biodegradable and often breaks into a period of one to three years. The 10-0 polypropylene (Prolene) looks like a really material unchanged, but noted that eventually loses its tensile strength and cracked by the action of UV rays. Polyester (like Dacron, Mersilene) is a truly non-resorbable material, and thickness of 11-0 has a similar strength to nylon 10-0. It is a little less elastic and therefore requires a closer fit with the help of keratoscope (the Mersilene of 10-0 should not be used, it is much rigid). Its hydrophobic behavior also avoids the tendency of nylon to join the cause and viscoelastic "soap films." The mersilene 11-0 is

According to the evidence of rejection time after surgery the rejection must be classified in hyperacute, acute or chronic rejection. The hyperacute rejection occurs within days after transplantation of the graft. This type of rejection has become rare, affecting less than 1% of transplant recipients due to improved pre-transplant projections. Hyperacute rejection occurs when the host antibodies recognize and bind to antigens of the graft (such as ABO blood group proteins or proteins of major histocompatibility complex). The binding of these antibodies lead to the initiation of the complement cascade, neutrophil recruitment, platelet activation, endothelial cell damage of the graft, and stimulation of coagulation reactions, which in turn lead to rapid thrombosis, loss of vascular integrity, heart tissue, and loss of

The acute rejection occurs in approximately fifty percent of transplant recipients experience acute rejection (with only 10% progressing to graft loss), which can occur several hours or days (even weeks) after transplantation. The incidence of acute rejection has decreased significantly with the successful use of immunosuppressants such as cyclosporine and azathioprine. The incidence of graft loss was reduced by the latest anti-rejection treatments. Acute rejection occurs when alloantigen-reactive T cells from the host to infiltrate the graft and become activated by contact with foreign proteins, related to the graft presented to

trephination and cause a receiver window oval or distorted.

other areas in order to minimize the risk of rejection.

another good choice (Barraquer at al. 2002).

graft function.

**4. Time of rejection of the corneal implant** 

chemical engineer Curtis Frank has created an artificial cornea polyacrylic acid and polyethylene nets, achieving a transparent material with high water content 80%. Future research is needed to view and evaluate the biocompatibility in vivo metabolic behavior with other nutrients to the cornea and allow epithelial cells attaching to the surface to prevent risk of infection acting as a layer of protection. Additionally, the bioengineer Jennifer Cochran came up with the addition of collagen to a surface of artificial cornea for better grip and other scientific using the technique of photolithography (manufacture of semiconductor materials) Frank and his team can also create patterns of microscopic pores around the edge of the implant. Thus, when the cornea is implanted in her patient's eye, the cells migrated through the pores by anchoring the cornea in the eye and helping to integrate the artificial material with natural tissue. This process reduces the number of sutures necessary to maintain the artificial cornea into place (Technology Review, MIT). There are major projects being carried out to sensitize the artificial cornea implants as the CORNEA EU project to produce artificial cornea has prompted efforts Joachim Storsberg, the Fraunhofer Institute for Applied Polymer Research IAP in German. His work has led to the creation of new versions of the artificial cornea implants has been shown to have less risk in terms of eye injuries.

#### **3.4 Another risk factors of post-keratoplasty complications**

Despite of microbiological and immunological complications are significant to prevent rejection. Those are relationship with the age of the receptor. The allograft rejection has been reported more common in children than in adults, possibly due to a more active immune system in younger patients. On those patients the pediatric transplant sometimes not without clear evidence of endothelial rejection. The rejection may even many years after transplantation. If irreversible failure occurs in patients in the age range amblyogenic, regrafting still may be indicated to advance the patient's visual development. Glaucoma is another common complication on these patients; also ocular hypertension can damage the optic nerve and threaten the survival of the graft and therefore the visual prognosis. The vulnerability of glaucoma in pediatric keratoplasty is potentially affected by the anterior segment abnormal structure or the use of steroids after surgery. Other complications, including endophthalmitis, choroidal hemorrhage, cataract, retinal detachment and phthisis bulbi are relatively rare but do occur.

Another authors reported Suture-related graft infection is a serious complication after penetrating keratoplasty and often leads to serious visual lost attributable to scarring, allograft reactions and also increased astigmatism. To reduce the risk of infection, they propose that it is necessary to ensure at each visit all sutures, that knots are well buried and that the sutures are covered by epithelium (Sonavane A. et al, 2003).

In the case of penetrating keratoplasty, the secondary astigmatism post penetrate keratoplasty (PK) is another complication to consider when using this technique. The first factors that may influence the refractive outcome is PK preexisting pathology in the recipient cornea, such as keratoconus, trauma and other causes of thinning or irregularity, especially peripheral, and therefore persist in the transplanted cornea. In cases of keratoconus, astigmatism may see a gradual change over the years, after an initial refractive result QP correct, due to thinning and corneal ecstasy ring at the receiver. Due to scarring, vascularization, the degrees of tension may form irregularities. Additionally, systemic diseases such as diabetes, collagen disease, recipient age, may also affect healing. The more homogeneous it is smaller the astigmatic error. During surgery, there are other parameters

chemical engineer Curtis Frank has created an artificial cornea polyacrylic acid and polyethylene nets, achieving a transparent material with high water content 80%. Future research is needed to view and evaluate the biocompatibility in vivo metabolic behavior with other nutrients to the cornea and allow epithelial cells attaching to the surface to prevent risk of infection acting as a layer of protection. Additionally, the bioengineer Jennifer Cochran came up with the addition of collagen to a surface of artificial cornea for better grip and other scientific using the technique of photolithography (manufacture of semiconductor materials) Frank and his team can also create patterns of microscopic pores around the edge of the implant. Thus, when the cornea is implanted in her patient's eye, the cells migrated through the pores by anchoring the cornea in the eye and helping to integrate the artificial material with natural tissue. This process reduces the number of sutures necessary to maintain the artificial cornea into place (Technology Review, MIT). There are major projects being carried out to sensitize the artificial cornea implants as the CORNEA EU project to produce artificial cornea has prompted efforts Joachim Storsberg, the Fraunhofer Institute for Applied Polymer Research IAP in German. His work has led to the creation of new versions of the artificial cornea implants has been shown to have less risk in

Despite of microbiological and immunological complications are significant to prevent rejection. Those are relationship with the age of the receptor. The allograft rejection has been reported more common in children than in adults, possibly due to a more active immune system in younger patients. On those patients the pediatric transplant sometimes not without clear evidence of endothelial rejection. The rejection may even many years after transplantation. If irreversible failure occurs in patients in the age range amblyogenic, regrafting still may be indicated to advance the patient's visual development. Glaucoma is another common complication on these patients; also ocular hypertension can damage the optic nerve and threaten the survival of the graft and therefore the visual prognosis. The vulnerability of glaucoma in pediatric keratoplasty is potentially affected by the anterior segment abnormal structure or the use of steroids after surgery. Other complications, including endophthalmitis, choroidal hemorrhage, cataract, retinal detachment and phthisis

Another authors reported Suture-related graft infection is a serious complication after penetrating keratoplasty and often leads to serious visual lost attributable to scarring, allograft reactions and also increased astigmatism. To reduce the risk of infection, they propose that it is necessary to ensure at each visit all sutures, that knots are well buried and

In the case of penetrating keratoplasty, the secondary astigmatism post penetrate keratoplasty (PK) is another complication to consider when using this technique. The first factors that may influence the refractive outcome is PK preexisting pathology in the recipient cornea, such as keratoconus, trauma and other causes of thinning or irregularity, especially peripheral, and therefore persist in the transplanted cornea. In cases of keratoconus, astigmatism may see a gradual change over the years, after an initial refractive result QP correct, due to thinning and corneal ecstasy ring at the receiver. Due to scarring, vascularization, the degrees of tension may form irregularities. Additionally, systemic diseases such as diabetes, collagen disease, recipient age, may also affect healing. The more homogeneous it is smaller the astigmatic error. During surgery, there are other parameters

terms of eye injuries.

bulbi are relatively rare but do occur.

**3.4 Another risk factors of post-keratoplasty complications** 

that the sutures are covered by epithelium (Sonavane A. et al, 2003).

to take into account to prevent complications: compression or deformation of the globe, ocular tone down a narrow cleft interpalpebral a misplaced speculum, a thread tension of the upper rectum or scleral support ring misplaced which can distort the cornea during the trephination and cause a receiver window oval or distorted.

During surgery it is necessary to have a team that includes appropriate microsurgical instruments apart from the ideal, a proper system illumination and a keratoscope surgical microscope. Postoperatively, many factors can also influence the final astigmatism, age, existing disease into the receiver, local and systemic steroid use local time each suture is kept before being withdrawn, leaving them to favor reports longer. It should be up on the controls to show signs of possible rejection, early withdrawal of sutures, traumatic or spontaneous ectasia, epithelial problems, and secondary infection. We must decide, first, the diameter of the graft and the window. Often it will be a compromise between including all opaque or affected area on one side and try not to reach the peripheral vascularized limb or other areas in order to minimize the risk of rejection.

The suture is probably the main factor that may influence the prevention or induction of astigmatism QP. It is important to correctly position each and every one of the points because one of them misplaced can induce astigmatism may not be discovered until the sutures are removed and can be difficult to correct with a secondary procedure. 10-0 nylon monofilament is still the reference material for the final suture button, but in reality is biodegradable and often breaks into a period of one to three years. The 10-0 polypropylene (Prolene) looks like a really material unchanged, but noted that eventually loses its tensile strength and cracked by the action of UV rays. Polyester (like Dacron, Mersilene) is a truly non-resorbable material, and thickness of 11-0 has a similar strength to nylon 10-0. It is a little less elastic and therefore requires a closer fit with the help of keratoscope (the Mersilene of 10-0 should not be used, it is much rigid). Its hydrophobic behavior also avoids the tendency of nylon to join the cause and viscoelastic "soap films." The mersilene 11-0 is another good choice (Barraquer at al. 2002).
