We reanalyse optical gravitational lens surveys from the literature in order to determine relative probabilities in the $lambda_{0}$-$Omega_{0}$ plane, using a softened singular isothermal sphere lens model. In addition, we examine a portion of the $lambda_{0}$-$Omega_{0}$ plane which includes all viable cosmological models; this is vital for comparison with other cosmological tests. The results are, within the errors, consistent with those of more specialised analyses, such as those concerning upper limits on $lambda_{0}$ in a flat universe. We note that gravitational lensing statistics can provide a quite robust LOWER limit on the cosmological constant as well, which could prove important in confirming current claims of a positive cosmological constant. At 95% confidence, our lower and upper limits on $lambda_{0}-Omega_{0}$, using lens statistics information alone, are respectively -3.17 and 0.3. For a flat universe, these correspond to lower and upper limits on $lambda_{0}$ of respectively -1.09 and 0.65.
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