Pterygium epithelium abnormal differentiation related to activation of extracellular signal-regulated kinase signaling pathway in vitro.

AIM: To investigate whether the abnormal differentiation of the pterygium epithelium is related to the extracellular signal-regulated kinase (ERK) signaling pathway in vitro. METHODS: The expression levels of phosphorylated ERK (P-ERK), keratin family members including K19 and K10 and the ocular master control gene Pax-6 were measured in 16 surgically excised pterygium tissues and 12 eye bank conjunctiva. In colony-forming cell assays, the differences in clone morphology and in K10, K19, P-ERK and Pax-6 expression between the head and body were investigated. When cocultured with the ERK signaling pathway inhibitor PD98059, the changes in clone morphology, colony-forming efficiency, differentiated marker K10, K19 and Pax-6 expression and P-ERK protein expression level were examined by immunoreactivity and Western blot analysis. RESULTS: The expression of K19 and Pax-6 decreased in the pterygium, especially in the head. No staining of K10 was found in the normal conjunctiva epithelium, but it was found to be expressed in the superficial cells in the head of the pterygium. Characteristic upregulation of P-ERK was observed by immunohistochemistry. The clone from the head with more differentiated cells in the center expressed more K10, and the clone from the body expressed more K19. The P-ERK protein level increased in the pterygium epithelium compared with conjunctiva and decreased when cocultured with PD98059. The same medium with the ERK inhibitor PD98059 was more effective in promoting clonal growth than conventional medium with 3T3 murine feeder layers. It was observed that the epithelium clone co-cultured with the inhibitor had decreased K10 expression and increased K19 and Pax-6 expression. CONCLUSION: We suggest ERK signaling pathway activation might play a role in the pterygium epithelium abnormal differentiation.

[Study on microsurgical procedures for pterygium operation and its therapeutic effects].

OBJECTIVE: To study the microsurgical procedures for the treatment of large primary pterygium and their therapeutic effects. To observe the recurrence rate, the changes of visual acuity after microsurgery and the pathological relationships between pterygium and cornea/sclera under the surgical microscope. METHODS: Forty-six eyes of forty-one patients with pterygium which invading the cornea over the pupil border were included. Pterygium was dissected by various methods under surgical microscope. The pathological relationship between the pterygium and cornea/sclera was observed. The lengths of the pterygium head and its three parts were measured. Degenerative Tenon's capsule was removed totally and the wound was covered by rotated conjunctival flaps. These patients were followed-up for 12.0 - 50.2 months (median: 22.4 months). Changes in visual acuity and recurrence rate after operation were observed. RESULTS: The average length of the total pterygium heads was (6.3 +/- 0.4) mm. The head was divided into three parts: the apical, loose and adhesive parts. The apical part was located at the top of the pterygium head with a length of (1.7 +/- 0.4) mm. The tissue of apical part was compact, hard, translucent and adhered to the cornea tissue. The adhesive part was a band in front of the anterior border of the limbus and paralleled to the limbus. The width of adhesive part was (0.9 +/- 0.1) mm and was tightly adhered to the cornea. The loose part lied between the apical and the adhesive part. The length of which was (3.6 +/- 0.4) mm and could be separated from the cornea easily. The neck and the body parts of pterygium could be separated easily from the limbus and sclera. Non-corrected visual acuity averaged 0.3 (ranged from finger count to 0.7) before the operation and averaged 0.7 (ranged from finger count to 1.5) 1 month postoperatively (Wilcoxon signed rank test u = 5.435, P < 0.01). Pterygium relapsed in 5 eyes with a recurrence rate of 11% (5/46). CONCLUSIONS: There is a regular pathological relationship between the pterygium and the cornea/sclera under surgical microscope, which is fundamental for the microsurgery of the pterygium. Extensively degenerated Tenon's capsule should be removed totally and the defect should be covered by rotated conjunctival flaps. The recurrence rate is low and the visual acuity increases significantly after the operation.

[Management of corneo-conjunctival malignant melanoma with "no touch technique" surgical excision and corneoscleral lamellar keratoplasty].

OBJECTIVE: To study the management of "no touch technique" surgical excision and corneoscleral lamellar keratoplasty in the treatment of corneo-conjunctival malignant melanoma. METHODS: Surgical excision for corneo-conjunctival malignant melanoma in six cases, from October 1989 to January 2004 in Zhongshan Ophthalmic Center, were performed. The entire tumors were removed in one piece without touching the tumor (no touch technique). The incision was outlined 4-6 mm outside the pigmented conjunctival mass, and 2 mm outside the corneal component. Dissecting deep enough without any tumor cell left to yield a tumor-free bed. After surgical incision, the host eyeball defect was covered with partial or total corneoscleral lamellar graft from fresh donor, and the conjunctiva defect was covered with or without amniotic membrane transplantation. All the patients were followed up to 6 months. RESULTS: The tumors in the remaining conjunctival margins were completely removed by local dissection combined with cryotherapy in the six cases. Three cases were treated with partial corneoscleral lamellar keratoplasty, two cases with total corneoscleral lamellar keratoplasty and one case with total corneoscleral lamellar keratoplasty plus amniotic membrane transplantation. All cases were subsequently treated with 0.01% thiotepa eyedrops and supplemental dacarbazine chemotherapy. At the average 43.5 months follow-up time (14.6 years to 6 months), no evidences of local recurrence of malignant melanoma or distant metastasis were observed. CONCLUSION: The clinical study suggests that using surgical excision of "no touch technique" to remove tumor in whole piece with corneoscleral lamellar keratoplasty is effective in the treatment of corneo-conjunctival malignant melanoma.