Solutions containing miotic agents: effects on corneal transendothelial electrical potential difference.

BACKGROUND

Anterior chamber miotic solutions are widely used during anterior chamber surgery. We examined the effects of solutions containing miotic agents such as carbachol and/or acetylcholine on corneal endothelial pumping activity.

METHODS

We monitored, in vitro, the transendothelial electrical potential difference of isolated rabbit corneal endothelial preparations. As controls, we used solutions without miotics.

RESULTS

We found that a solution containing 55 mM acetylcholine and minimal amounts of salts (Miochol E) maintains transendothelial electrical potential difference some 30% above control levels for up to 4 h. Two other solutions, one including balanced salts and 0.55 mM carbachol (Miostat), the other a mixture of 0.19 mM carbachol and 55 mM acetylcholine plus minimal salts, are adequate to maintain the potential difference at control levels. Lastly, a solution with acetylcholine but without any salts (Miochol) greatly decreases the potential difference, to 30% of the control level, in 100 min.

CONCLUSION

Our results indicate that: (1) 55 mM (1%) acetylcholine stimulates the endothelial electrical potential difference; (2) addition of 0.19 mM (0.003%) carbachol negates the stimulatory effect of acetylcholine; and (3) absence of electrolytes severely depresses the endothelial electrical activity.