SANTA CLARA, Calif., Nov. 13 -- VISX Inc. said a Tokyo district court ruled to uphold its patent in an infringement lawsuit against Nidek Co. Ltd., a Japanese optical equipment maker. The ruling is the latest in a dispute between the two companies over intellectual property rights covering vision-correction lasers. In August, Nidek filed a patent infringement suit against VISX Japan K.K., Japan Focus Co. Ltd. and JFC Sales Plan Co. Ltd., alleging infringement of 2809959 Japanese Patent ("the 959 patent"). Last month, a US federal judge issued a preliminary ruling in favor of VISX.