Objective: To explore the lymphangiogenesis process in alkali burned human cornea and to discuss factors modulating this process.
Methods: It was a retrospective case series study. Twenty-two cases (22 eyes) of hospitalized patients suffering from alkali burned cornea and requiring keratoplasty from January to December 2005 were analyzed retrospectively. Before surgery, injury time (IT) and injury degree (ID) were recorded. Furthermore, inflammation index (II) and relative area of new blood vessels (BVA) were measured. Cornea specimens were assessed for lymphatic vessel counting (LVC) and blood vessel counting (BVC) via immunohistochemical staining and transmission electronic microscopy. Meanwhile, HE staining was also performed to observe infiltration of polymorphonuclear (PMN) leucocytes in corneal tissues. Student t-test, Pearson correlation test and Stepwise regression analysis were used to investigate the influencing factors.
Results: In these 22 cases, IT was (57.62 +/- 31.72) months; ID was (12.00 +/- 2.76) scores; II was (2.32 +/- 2.63) scores; BVA was (29.79% +/- 18.61%); BVC was (14.45 +/- 9.29) units; LVC was (2.73 +/- 4.57) units and PMN was (13.45 +/- 13.09) units. In 7 patients with IT more than 64 months (accounted for 32% of 22 cases), lymphangiogenesis [(8.6 +/- 3.8) units] and hemangiogenesis [(22.3 +/- 11.1) units] were both present. In these 7 patients, the whole number of LVC was 60 units, constituting 16% of all vessels (BVC+LVC = 378 units). The correlation coefficient of LVC with IT, ID, BVA, PMN and II was -0.673, 0.604, 0.755, 0.806 and 0.873, respectively. P value of all these correlations was less than 0.05. Further regression analysis revealed that LVC could be approximately calculated from II and BVA multiplying certain constant coefficients separately (resulting in lymphatic index, LI). Lymphatic vessels with characteristic ultrastructures and inflammatory cells were identified by transmission electronic microscopy.
Conclusions: Lymphatic vessels exist in part of alkali burned human corneas and may be estimated through II and BVA indirectly. Lymphatic index may be a convenient and useful clinical index for evaluating lymphangiogenesis in corneal alkali burn.