The Effect of Amniotic Membrane Transplantation or Conjunctival Autografts on the Tear Mucins MUC5A and MUC2 After Pterygium Resection: A Six-Month Follow-Up.

PURPOSE

Pterygium is an ocular surface disease characterized by the invasion of fibrovascular tissue from the bulbar conjunctiva to the cornea and is associated with abnormal tear function caused by changes in tear composition and osmolarity. In this study, the effect of two different surgical techniques to remove primary pterygium: conjunctival autograft surgery (CAG) and amniotic membrane transplantation (AMT), on changes in MUC2 and MUC5AC tear mucins concentration were evaluated.

METHODS

Forty-four patients (>18 years old) with primary unilateral pterygium (> 1.0 mm long, measured from the limbus to the apex on the cornea) were randomly enrolled, and assigned to the AMT or CAG group by using the permuted block technique. Patients with systemic inflammatory diseases or other eye comorbidities were excluded from the study. Tear break-up time (TBUT) and best-corrected visual acuity (BCVA) assessments were performed before surgery and at 1, 3, and 6 months after surgery. Tears were collected concurrently with the clinical evaluations, and MUC2 and MUC5AC concentrations were subsequently measured by means of ELISA.

RESULTS

At 6 months after CAG or AMT, TBUT and BCVA were significantly lower (P < 0.05) in comparison with the baseline values in the study subjects. The tear mucin concentrations of both MUC2 and MUC5AC were significantly higher (P < 0.0001) in patients with pterygium before any surgical procedure than in healthy individuals. The concentration of MUC2 increased at 1 and 3 months after CAG surgery and decreased at 6 months; however, the MUC2 concentration decreased on the AMT group in all time point measurements. Interestingly, the MUC5AC concentration significantly increased at 1 month after AMT or CAG and then decreased at 3 and 6 months after surgery. Finally, an inverse correlation was found between both MUC2 and MUC5AC tear mucins concentration and the TBUT.

CONCLUSIONS

These results suggest that pterygium excision via both CAG or AMT changes the concentrations of the tear mucins MUC2 and MUC5AC during the evaluated times, and these changes could affect tear film stability and clinical recovery after pterygium treatment.

TRANSLATIONAL RELEVANCE

The tear film stability during pterygium excision was evaluated to determine adequate treatments.