Use of a corneal stroma perfusion technique and transmission electron microscopy to assess ultrastructural changes associated with exposure to slightly acidic pH 5.75 solutions.
OBJECTIVE
To quantitatively assess the effects of pH on the corneal stroma under an applied hydrostatic pressure.


METHODS
Sclera-stroma preparations from adult sheep eyes were perfused with isotonic mixed salts solutions at 37 degrees C for 9 hr under an applied hydrostatic pressure and then fixed for electron microscopy.


RESULTS
Exposure to pH 7.25 solutions resulted in slight swelling, retention of lamellae, and the keratocytes were intact. The collagen fibril diameter was 40.0+/-3.5 nm, which was the same as non-perfused samples (40.9+/-3.7 nm). Perfusion at pH 5.75 resulted in slight compaction, some disorganization of the lamellae, and almost total destruction of the keratocytes. The collagen fibril profiles in cross section were irregular and reduced to a mean of 30.2+/-3.5 nm (p<0.001).


CONCLUSIONS
Exposure of the corneal stroma to slightly acid pH at the so-called critical electrolyte concentration pH for proteoglycan-ionic interactions can cause substantial structural changes.
Doughty
Michael J
MJ
Department of Vision Sciences, Glasgow-Caledonian University, Glasgow, Scotland. m.doughty@gcal.ac.uk
Bergmanson
Jan P G
JP
D000818:Animals; D003094:Collagen / Q000648:ultrastructure; D015715:Corneal Edema; D003319:Corneal Stroma / Q000187:drug effects* / Q000648:ultrastructure*; D006863:Hydrogen-Ion Concentration; D006874:Hydrostatic Pressure; D007552:Isotonic Solutions / Q000737:chemistry / Q000494:pharmacology*; D046529:Microscopy, Electron, Transmission; D009994:Osmolar Concentration; D012756:Sheep
D007552:Isotonic Solutions; D003094:Collagen