Lens membrane damage associated with cryoextraction.

The effects of cryoextraction on transport characteristics of rabbit lenses were evaluated by measuring Na+ and Ca++ levels, initial rates of 86Rb accumulation, and bioelectric potentials. The results demonstrate that membrane damage results from cryoextraction and is partially reversible during subsequent culture. While the decline in potential often exceeds 30 mV, maximum recovery of 80% occurs during a 1-hour incubation in TC199 at 37 C. Changes in the integrity of the membranes also are indicated by the finding that rates of 86Rb accumulation in cryoextracted lenses are approximately 44% less than the rates found in control lenses after a 20-hour culture in TC199. The degree of damage incurred by lens membranes also is reflected by a 10% increase in Na+ and 20% increase in Ca++ levels during 3 hours of culture. After extended culture periods, further increases in the concentration of Na+ (40%) and Ca++ (120%) were found to occur. Brief exposure of cryoextracted rabbit lenses to physiologic saline in a manner similar to that employed for photographic documentation of cataracts resulted in a marked decline in potential, 86Rb uptake, and an increase in Na and Ca content. In contrast, saline had little or no effect on these parameters in lenses excised by cutting the zonules. The results suggest that the observed decline in 86Rb accumulation in a limited number of cryoextracted cortico-nuclear cataracts compared with clear eye bank lenses may be attributed, in part, to damage to lens membranes by cryoextraction.(ABSTRACT TRUNCATED AT 250 WORDS)