Effect of 1- and 6-Hour-Delayed Corneal Collagen Cross-Linking on Corneal Healing in a Rabbit Alkali-Burn Model: Clinical and Histological Observations.

Abstract

To study the effect of 1- and 6-hour-delayed corneal collagen cross-linking (CXL) on wound-healing of experimental alkali burns of the cornea. Twenty-four albino rabbits were used. Alkali burns were created using 1 M NaOH. The animals were divided randomly into 2 groups: group 1 (control group, n = 6) and group 2 (experimental group, n = 18). The experimental group was further divided into 3 subgroups as follows: group 2A, untreated (non-CXL) subgroup; group 2B, 1-hour-delayed CXL treatment subgroup; and group 2C, 6-hour-delayed CXL treatment subgroup. All rabbits were examined periodically for 21 days after treatment and then killed. The corneas were excised and histologically examined. Corneal ulceration, edema, and opacity scores were 4.0 ± 1.64, 1.6 ± 0.65, and 3.5 ± 1.21 in group 2A, 1.5 ± 1.76, 1.3 ± 0.87, and 3.1 ± 1.12 in group 2B, and 2.0 ± 1.90, 1.5 ± 0.79, and 3.3 ± 1.09 in group 2C, respectively. These scores were significantly less in groups 2B and 2C than in group 2A (P = 0.023, P = 0.043, and P = 0.034, respectively). Corneal epithelialization, evident upon staining, was best in group 2B and worst in group 2A (P = 0.012). Histopathology revealed that destruction of corneal collagen fibers and infiltration of inflammatory cells into corneal tissue were reduced in groups 2B and 2C compared with group 2A. We found that CXL treatment exerted positive effects on severe alkali-induced corneal burns. However, the effects were more pronounced in the 1-hour treatment group. We believe that CXL treatment may be a possible treatment for corneal alkali burn.