**6. Application of MMC in the treatment of pterygium excision**

MMC is an anti-tumor antibiotic isolated from the filtrate of Streptomyces cephalosporin. It inhibits the synthesis of DNA, RNA, and protein and is radiomimetic in many of its actions [31]. It could reduce tissue adhesions and scar formation that has been widely adopted in pterygium surgery to lower the recurrence rate [32]. The purpose of the use of MMC as an adjunctive treatment is to prevent the recurrence of pterygium after the surgery [33]. It has been reported that the wound tissue has not been completely repaired within 2 weeks after pterygium resection. Local use of MMC is prone to lead to ischemic necrosis of wound tissue, especially for patients with bulbar conjunctival flap transplantation [34]. Research [35] has shown that pterygium excision with a free conjunctival autograft combined with intraoperative low-dose MMC is a safe and effective technique in pterygium surgery. MMC can prevent vascular regeneration in the surgical field, prevent fibroblast proliferation and scar formation, and reduce the recurrence rate after pterygium surgery. Intraoperative administration of mitomycin C at 0.05% is safe and effective in preventing pterygium recurrences [36]. Gao et al. [37] compared the clinical efficacy of treatment on recurrent pterygium using different concentration MMC in the pterygium excision operation combined with the corneal limbal stem cell autografting. In their study, complications are corneal edema, corneal ulcer, and conjunctival flap infection. Scleral necrosis occurs in 0.2–4.5% of patients, and higher risk is linked to adjunctive use of MMC, especially more concentrated or repeated doses [38]. It was reported that a case of corneoscleral melt that occurred 50 years after resection of pterygium with postoperative administration of MMC [39]. The application

**49**

condition [48].

**8. Summary**

*Recent Advances in the Effects of Various Surgical Methods on Tear Film after Pterygium Surgery*

of 0.2 mg/ml MMC during operation for 3 minutes could effectively control fiber hyperplasia of conjunctivas and there are no complications on cornea and sclera [40]. Study [41] shows that the dry eye symptoms, basic tear secretion and BUT values of the MMC group are significantly better than the simple pterygium excision group. The difference between the two groups is statistically significant (p < 0.05). Therefore, it is believed that the treatment of pterygium excision combined with MMC has little effect on the stability of tear film and the secretion of basic tears, and the cure rate is high, which is an effective method for treating pterygium [42]. There is no significant difference in the cure rate and recurrence rate between pterygium excision combined with MMC and pterygium excision combined with autologous limbal stem cell transplantation (p > 0.05), both of which can effectively treat primary pterygium, but pterygium excision combined with MMC treatment will not destroy the ocular surface microenvironment, and the operation is easy to master, which is worthy of clinical promotion [43]. However, some studies have shown that the use of 0.2 g/L MMC in the treatment of simple pterygium excision showed signs of significant improvement in ocular surface environment early after surgery, and patients who use 0.29/L MMC are observed obvious ocular surface damage, keratinization of epithelial cells, loss of normal cuboid morphology, loose connection between cells, increased cell gap, increased nuclear-to-plasma ratio, and marked decrease in goblet cell density in analyzed area 3 months after surgery [44].

By combining autologous corneal limbal stem cell transplantation with conjunctival flap and amnion transplantation, the barrier between corneal epithelium and conjunctival epithelium is maintained and the invasion of foreign conjunctival tissue is prevented, so that the recurrence of pterygium and relevant complications are reduced [45]. The operation of transplantation of amniotic membrane and limbal stem cells can further reduce the postoperative recurrence rate [46]. Tear function is abnormal in patients with recurrent pterygium. The tear functions in patients with recurrent pterygium can improve significantly after combined surgery, restore the cornea stem cells and cohesion margin health conjunctival, and promote the ocular surface reconstruction perfect [47]. Tear film stability of pterygium excision combined with limbal stem cell and amniotic membrane transplantation is better than that of pterygium excision combined with limbal stem cell transplantation or amniotic membrane transplantation in early postoperative stage, but the forward performance and severity of xerophthalmia after surgical treatment of pterygium are about the same. Operation method should be chosen according to the patient's

Pterygium is a common ocular surface disease, and the prevalence rate is high. The main treatment method is surgical resection. The recurrence rate and incidence of postoperative dry eye after traditional simple pterygium resection is high. The recurrence rate and the incidence of dry eye of pterygium excision combined with autologous limbal stem cell transplantation is low, so it is most widely used currently. The healthy conjunctival tissue will not be damaged in combined amniotic membrane transplantation which provides conditions for glaucoma filtration surgery. Combined use of low concentration of MMC can effectively reduce the recurrence rate of pterygium, easy to operate, but there are risks of long-term

*DOI: http://dx.doi.org/10.5772/intechopen.90635*

**7. Other surgical methods**

*Recent Advances in the Effects of Various Surgical Methods on Tear Film after Pterygium Surgery DOI: http://dx.doi.org/10.5772/intechopen.90635*

of 0.2 mg/ml MMC during operation for 3 minutes could effectively control fiber hyperplasia of conjunctivas and there are no complications on cornea and sclera [40]. Study [41] shows that the dry eye symptoms, basic tear secretion and BUT values of the MMC group are significantly better than the simple pterygium excision group. The difference between the two groups is statistically significant (p < 0.05). Therefore, it is believed that the treatment of pterygium excision combined with MMC has little effect on the stability of tear film and the secretion of basic tears, and the cure rate is high, which is an effective method for treating pterygium [42]. There is no significant difference in the cure rate and recurrence rate between pterygium excision combined with MMC and pterygium excision combined with autologous limbal stem cell transplantation (p > 0.05), both of which can effectively treat primary pterygium, but pterygium excision combined with MMC treatment will not destroy the ocular surface microenvironment, and the operation is easy to master, which is worthy of clinical promotion [43]. However, some studies have shown that the use of 0.2 g/L MMC in the treatment of simple pterygium excision showed signs of significant improvement in ocular surface environment early after surgery, and patients who use 0.29/L MMC are observed obvious ocular surface damage, keratinization of epithelial cells, loss of normal cuboid morphology, loose connection between cells, increased cell gap, increased nuclear-to-plasma ratio, and marked decrease in goblet cell density in analyzed area 3 months after surgery [44].

### **7. Other surgical methods**

*Ocular Surface Diseases - Some Current Date on Tear Film Problem and Keratoconic Diagnosis*

effectively reduce inflammation, promote wound healing, and anti-fibrosis [25]. The recurrence rate of pterygium excision combined with amniotic membrane transplantation was significantly lower than that of single pterygium excision group [26]. Pterygium excision combined with amniotic membrane transplantation mainly inhibits fibroplasia in the operation area, inhibits leukocyte activation, reduces inflammatory reaction, reduces scar formation, inhibits vascularization, and prevents recurrence of pterygium [27]. Yao [28] compared tear BUT and Schirmer I test at preoperatively, 1, 3 months postoperatively between simple pterygium excision group and pterygium excision combined with amniotic membrane transplantation group, and ocular surface temperature and dry eye symptom score were taken at 2 months after operation. Pterygium excision combined with amniotic membrane transplantation can effectively improve the dry eye, which is conducive to the stability of tear film function. Some authors [29] compared two surgical methods (pterygium excision combined with conjunctival flap transplantation and pterygium excision combined with amniotic membrane transplantation) on tear function. BUT and Schirmer I were shortened on both groups at 1 and 3 months postoperation, and the differences were significant (p < 0.05). Pterygium excision affects tear film function at the early postoperative stage. Tear film function returns to preoperative levels 3 months after surgery. Influence of pterygium excision combined with amniotic membrane transplantation on function of the tear film is less than that of pterygium excision combined with conjunctival flap transplantation at early postoperative stage. Amniotic membrane transplantation can limit fibrosis of the sub-conjunctival tissue, improve the success rate of surgery, and reduce the incidence of postoperative dry eye. The reason is the basement membrane surface of the amniotic membrane and the fibroblasts of the conjunctiva stimulate the differentiation of conjunctival goblet cells, keeping the conjunctiva and cornea of

the postoperative patients moist, reducing the incidence of dry eye [30].

**6. Application of MMC in the treatment of pterygium excision**

MMC is an anti-tumor antibiotic isolated from the filtrate of Streptomyces cephalosporin. It inhibits the synthesis of DNA, RNA, and protein and is radiomimetic in many of its actions [31]. It could reduce tissue adhesions and scar formation that has been widely adopted in pterygium surgery to lower the recurrence rate [32]. The purpose of the use of MMC as an adjunctive treatment is to prevent the recurrence of pterygium after the surgery [33]. It has been reported that the wound tissue has not been completely repaired within 2 weeks after pterygium resection. Local use of MMC is prone to lead to ischemic necrosis of wound tissue, especially for patients with bulbar conjunctival flap transplantation [34]. Research [35] has shown that pterygium excision with a free conjunctival autograft combined with intraoperative low-dose MMC is a safe and effective technique in pterygium surgery. MMC can prevent vascular regeneration in the surgical field, prevent fibroblast proliferation and scar formation, and reduce the recurrence rate after pterygium surgery. Intraoperative administration of mitomycin C at 0.05% is safe and effective in preventing pterygium recurrences [36]. Gao et al. [37] compared the clinical efficacy of treatment on recurrent pterygium using different concentration MMC in the pterygium excision operation combined with the corneal limbal stem cell autografting. In their study, complications are corneal edema, corneal ulcer, and conjunctival flap infection. Scleral necrosis occurs in 0.2–4.5% of patients, and higher risk is linked to adjunctive use of MMC, especially more concentrated or repeated doses [38]. It was reported that a case of corneoscleral melt that occurred 50 years after resection of pterygium with postoperative administration of MMC [39]. The application

**48**

By combining autologous corneal limbal stem cell transplantation with conjunctival flap and amnion transplantation, the barrier between corneal epithelium and conjunctival epithelium is maintained and the invasion of foreign conjunctival tissue is prevented, so that the recurrence of pterygium and relevant complications are reduced [45]. The operation of transplantation of amniotic membrane and limbal stem cells can further reduce the postoperative recurrence rate [46]. Tear function is abnormal in patients with recurrent pterygium. The tear functions in patients with recurrent pterygium can improve significantly after combined surgery, restore the cornea stem cells and cohesion margin health conjunctival, and promote the ocular surface reconstruction perfect [47]. Tear film stability of pterygium excision combined with limbal stem cell and amniotic membrane transplantation is better than that of pterygium excision combined with limbal stem cell transplantation or amniotic membrane transplantation in early postoperative stage, but the forward performance and severity of xerophthalmia after surgical treatment of pterygium are about the same. Operation method should be chosen according to the patient's condition [48].

#### **8. Summary**

Pterygium is a common ocular surface disease, and the prevalence rate is high. The main treatment method is surgical resection. The recurrence rate and incidence of postoperative dry eye after traditional simple pterygium resection is high. The recurrence rate and the incidence of dry eye of pterygium excision combined with autologous limbal stem cell transplantation is low, so it is most widely used currently. The healthy conjunctival tissue will not be damaged in combined amniotic membrane transplantation which provides conditions for glaucoma filtration surgery. Combined use of low concentration of MMC can effectively reduce the recurrence rate of pterygium, easy to operate, but there are risks of long-term

complications such as scleral lysis. Amniotic membrane transplantation combined with autologous limbal stem cell transplantation can reduce the recurrence rate of pterygium and recurrent pterygium, and has little effect on the tear film. The surgical method can be selected according to the actual situation of pterygium patients.
