Lymphatic Microvessel Density as a Predictive Marker for the Recurrence Time of Pterygium: A 3-year Follow-up Study

Abstract

Purpose: To investigate whether lymphatic microvessel density (LMVD) could be used as a predictive marker for the recurrence time of pterygia

Methods: This was a prospective case series study. A total of 96 patients with unilateral eye primary nasal pterygia were included. The included patients were clinically evaluated to grade the severity of their pterygia (32 Grade 1, 29 Grade 2, and 35 Grade 3) before they underwent bare sclera resection with the use of mitomycin C. Excised tissues from the 96 patients and the 10 normal nasal conjunctiva obtained from age-matched donor eyeballs (controls) were immunostained with LYVE-1 and CD31 monoclonal antibodies to evaluate lymphatic microvessel density (LMVD) and blood microvessel density (BMVD). The included patients were followed up for 3 years or until the identification of pterygium recurrence, which was defined as fibrovascular regrowth past the limbus in a previously compromised area. The recurrence time (RT) for a pterygium was calculated, and its relationship with LMVD and/or BMVD was statistically analyzed.

Results: In total, there were 24 cases of pterygium recurrence. The recurrence rate (RR) of Grade 1 was 28.1% (9/32), Grade 2 was 24.1% (7/29), and Grade 3 was 22.9% (8/35), as classified in the primary pterygium (p>0.05); the overall RR was 25% (24/96) for all patients during the 3-year follow-up. In the tissue analysis, there were a small number of CD31 (+), LYVE-1(-) BMVD and only a few CD31 (weak), LYVE-1(+) LMVD in the 10 normal nasal conjunctiva tissues. BMVD and LMVD increased significantly in the pterygium tissue compared to the control tissue and were significantly correlated with both the width and area of pterygium in Grades 1-3 (all p values < 0.05). However, RT was not correlated with BMVD or pterygium grade, but LMVD was significantly and negatively correlated with RT within each group and in the total patient cohort. Furthermore, we determined that an LMVD greater than 20 in the surgical specimens was predictive of pterygium recurrence.

Conclusions: The LMVD of surgical specimens is an independent risk factor and a valuable predictive factor for the recurrence time of pterygia.

Keywords: 421 anterior segment • 474 conjunctiva • 554 immunohistochemistry