Changes of Ocular Surface and the Inflammatory Response in a Rabbit Model of Short-Term Exposure Keratopathy.
OBJECTIVE
To evaluate the ocular surface change and the inflammatory response in a rabbit model of short-term exposure keratopathy.


METHODS
Short term exposure keratopathy by continuous eyelid opening was induced in New Zealand white rabbits for up to 4 hours. Ultrasound pachymetry was used to detect central total corneal thickness. In vivo confocal microscopy and impression cytology were performed to evaluate the morphology of ocular surface epithelium and the infiltration of inflammatory cells. Immunohistochemistry for macrophage,neutrophil, CD4(+) T cells, and CD8(+) T cells were performed to classify the inflammatory cells. Scanning electron microscopy(SEM) was performed to detect ocular surface change.The concentrations of IL-8, IL-17, Line and TNF-αwere analyzed by multiplex immunobead assay. TUNEL staining was performed to detect cellular apoptosis.


RESULTS
Significant decrease ofcentral total cornealthickness were found within the first 5 minutes and remained stable thereafter, while there were no changes of corneal epithelial thickness.No significant change of corneal, limbal and conjunctival epithelial morphology was found by in vivo confocal microscopy except the time dependent increase of superficial cellular defects in the central cornea. Impression cytology also demonstrated time dependent increase of sloughing superficial cells of the central cornea. Aggregations ofinflammatory cells were found at 1 hour in the limbal epithelium, 2 hours in the perilimbal conjunctival epithelium, and 3 hours in the peripheral corneal epithelium.In eyes receiving exposure for 4 hours, the infiltration of the inflammatory cells can still be detected at 8 hours after closing eyes.Immunohistochemical study demonstrated the cells to be macrophages, neutrophils, CD4-T cells and CD-8 T cells.SEM demonstrated time-depending increase of intercellular border and sloughing of superficial epithelial cells in corneal surface. Time dependent increase of IL-8, IL-17 and TNF-α in tear was found.TUNEL staining revealed some apoptotic cells in the corneal epithelium and superficial stroma at 3 hours after exposure.


CONCLUSIONS
Short term exposure keratopathy can cause significant changes to the ocular surface and inflammatory response. Decrease of central total corneal thickness, aggregation of inflammatory cells, and cornea epithelial cell and superficial keratocyte apoptosis were found no less than 4 hours following the insult.
Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
Chun-Ting
CT
Lai
Department of Anesthesia, Min-Sheng General Hospital, Tao-Yuan City, Taiwan.
Wei-Chieng
WC
Yao
Deparment of Ophthalmology, Cathay General Hospital, Taipei, Taiwan.
Szu-Yuan
SY
Lin
Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
Hsin-Yu
HY
Liu
Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
Huai-Wen
HW
Chang
Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan; Center of Corneal Tissue Engineering and Stem Cell Biology, National Taiwan University Hospital, Taipei, Taiwan.
Fung-Rong
FR
Hu
Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan; Center of Corneal Tissue Engineering and Stem Cell Biology, National Taiwan University Hospital, Taipei, Taiwan.
Wei-Li
WL
Chen
D000818:Animals; D017209:Apoptosis; D001767:Blinking; D015496:CD4-Positive T-Lymphocytes / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000473:pathology; D003315:Cornea / Q000473:pathology*; D060527:Corneal Keratocytes / Q000737:chemistry / Q000648:ultrastructure; D003890:Desiccation; D004195:Disease Models, Animal; D004848:Epithelium / Q000737:chemistry / Q000473:pathology; D005260:Female; D007249:Inflammation; D020381:Interleukin-17 / Q000032:analysis; D016209:Interleukin-8 / Q000032:analysis; D007638:Keratoconjunctivitis Sicca / Q000473:pathology*; D016850:Limbus Corneae / Q000737:chemistry / Q000648:ultrastructure; D008264:Macrophages / Q000473:pathology; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D009504:Neutrophils / Q000473:pathology; D011817:Rabbits; D013499:Surface Properties; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D020381:Interleukin-17; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha