Acute effects of ultraviolet-B irradiation on the corneal surface of the pigmented rabbit studied by quantitative scanning electron microscopy.
The eyes of female pigmented rabbits were exposed to a single dose of UV-B (300 +/- 9 nm, 0.05 J/cm2 total dose) between 13.30 and 15.00 h. The average irradiance was 225 +/- 36 microW/cm2 delivered over 191 to 264 s. At various time periods thereafter (24, 48, 72 and 96 h post-irradiation), the animals were euthanized by pentobarbital overdose and the eyes fixed with 2% glutaraldehyde in 80 mM cacodylate buffer (pH 7.4, total osmolarity of 330-340 mOsm/L). Corneal quadrants were examined by high resolution scanning electron microscopy at 100 X and 500 X at-stage magnification at central, mid-peripheral and peripheral sites. The micrographs from the central cornea were subjected to a quantitative analysis using a computer based digitization system. A peak effect was observed at 48 h at which cellular exfoliation was noted at the corneal apex. In the region immediately adjacent to the exfoliating cells, the number of light and dark electron reflex cells decreased to 48 h while the numbers of medium-reflex cells decreased after 48 h. The relative surface area of all cells was also decreased at 48 h compared to unirradiated controls. Significant recovery was observed by 96 h. Mid-peripheral and peripheral sites were largely unaffected by this just supra-threshold irradiation.
Clarke
S M
SM
School of Optometry Waterloo, Ontario, Canada.
Doughty
M J
MJ
Cullen
A P
AP
D000818:Animals; D002452:Cell Count / Q000528:radiation effects; D003315:Cornea / Q000528:radiation effects* / Q000648:ultrastructure; D004848:Epithelium / Q000528:radiation effects / Q000648:ultrastructure; D005260:Female; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D014466:Ultraviolet Rays / Q000009:adverse effects*