[The ocular surface of severe alkali burns patients on confocal microscopy].

Objective: To analyze the morphology on the ocular surface of severe alkali burns patients by in vivo laser scanning confocal microscopy.

Methods: This research was a retrospective observation case series. From February to November 2008 in Eye Ear Nose and Throat Hospital of Fudan University, 39 alkali burns patients who classified as III or IV according to Roper-Hall classification were enrolled in this study. They were divided into four groups according to the course of disease: A (less than 3 months), B (3 - 6 months), C (6 - 12 months) and D (over 12 months). In vivo laser scanning confocal microscopic examinations were performed on the injured cornea, the limbus and the bulbar conjunctiva and the images were recorded. The morphology of the injured cornea, the limbus and the bulbar conjunctiva was analyzed and the densities of the inflammatory cells and dendritic cells in the limbus were calculated. One-way analysis of variance was used to compare the means of the inflammatory cells and dendritic cells. Subsequently the data between two groups were analyzed by least significant difference.

Results: The corneal epitheliums of the patients in Group A manifested large irregular features with hyperreflective cytoplasm and hyporeflective nuclei, sometimes losing cell features. There were numerous small hyperreflective inflammatory cells in groups beneath the superficial epitheliums. Shallow corneal stroma was edema, and it was hard to discriminate the morphology of the stromal cells. Deep stromal cells were in the activated state. The images of the endothelial layer were unclear. In Group B and Group C, there were the same manifestation of the superficial epitheliums as the group A and it disappeared in Group D. The inflammatory cells beneath the superficial epitheliums reduced and some residual basal epitheliums and hyperreflective conjunctiva-like epitheliums were visible in Group B and Group C. In Group D, there were small oval tight-arranged cells with punctiform hyperreflective nuclei instead of normal corneal basal epitheliums. In Group B, it was still hard to discriminate the morphology of the shallow stroma cells. Deep stromal cells were still in the activated state. In Group C and Group D, corneal stroma was replaced by the fibrous tissues. The images of the endothelial layer were still unclear in the other groups. The Vogt palisades in the limbus of the severe alkali burns patients were destroyed in all groups. There were rich vascular nets in the limbus. The densities of the limbal inflammatory cells in four groups were (4023 +/- 343), (2975 +/- 246), (2652 +/- 375), (2679 +/- 299) cells/mm(2), respectively. Significant difference in inflammatory cell density was found among groups (F = 40.001, P = 0.000). The densities of the limbal dendritic cells in four groups were (106 +/- 19), (132 +/- 35), (141 +/- 26), (98 +/- 24) cells/mm(2), respectively. Significant difference in dendritic cell density was found among groups (F = 8.053, P = 0.000). When the injured area of the conjunctiva was limited, it was hard to discriminate the morphology of the conjunctival epitheliums in both Group A and Group B. Numerous inflammatory cells infiltrated in the conjunctival lamina propria and goblet cells were invisible. In Group C and Group D, the conjunctival epitheliums were almost normal. There were still some inflammatory cells and dendritic cells in the conjunctival lamina propria, and there were residual goblet cells visible in parts of the patients. When the injured area of the conjunctiva was large, the conjunctivas in four groups displayed hyperreflective stripe fibrous tissues instead of normal conjunctival epitheliums.

Conclusions: The application of laser scanning confocal microscopy indicates that there is much difference on the cellular morphology of the ocular surface of severe alkali burns patients among diverse courses of the disease. The technique is a useful tool to the observation on the ocular surface of severe alkali burns patients.