Failure of potassium siphoning by Müller cells: a new hypothesis of perfluorocarbon liquid-induced retinopathy.
OBJECTIVE
To determine the effect of perfluorocarbon liquid (PFCL)-induced abolition of potassium siphoning by the vitreal end feet of Miller cells.


METHODS
Porcine eyecups were filled with stained balanced salt solution and PFCLs (perfluorodecalin, perfluorooctane, perfluoroperhydrophenanthrene or the semifluorocarbon perfluorohexylhexane). With optical coherence tomography, the distance between PFCL and retina was determined, and the size of the aqueous space covering the retinal surface was estimated. The data were used to calculate the retinal potassium siphoning into small aqueous volumes.


RESULTS
The distance between PFCL and retinal surface was found to be less than 5 to 10 microm with any PFCL tested. The resultant volume of the aqueous space was too small to act as a sufficient sink for K+ ion siphoning.


CONCLUSIONS
A certain threshold volume of vitreal fluid seems to be necessary for efficient buffering of intraretinal increases of K+ and perhaps other (e.g., H+) ions through the Müller cells. When the aqueous fluid is replaced by a PFCL (or by silicone oil) for longer periods, the outer retina becomes subject to long-lasting K+ accumulation, and consequent neurodegeneration and reactive gliosis occurs. The authors propose to search for new vitreous-substituting fluids with the capability to dissolve ions.
Winter
M
M
Department of Ophthalmology, University of Kiel, Germany. mwinter@ophthalmol.uni-kiel.de
Eberhardt
W
W
Scholz
C
C
Reichenbach
A
A
D000818:Animals; D005466:Fluorocarbons / Q000009:adverse effects*; D008962:Models, Theoretical; D009457:Neuroglia / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D012164:Retinal Diseases / Q000139:chemically induced* / Q000378:metabolism; D013552:Swine; D014054:Tomography / Q000379:methods
D005466:Fluorocarbons; D011188:Potassium