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 .