Converting old .mat files to v7.3?

I want to make use of the v7.3 .mat files ability to load part of a variable. However, all the .mat files I'm working with are older. Is there any way to convert them? Currently I read the whole files and pick out the data I want, but I run out of memory as I scale up making it not feasible. Or are there any other ways to read specific data points from .mat files without loading the whole file?

Thanks!

[Erik Sellberg]

Nevermind I solved it. If anyone else has the same problem, see:

https://se.mathworks.com/matlabcentral/answers/1455559-convert-mat-file-to-v7-3

[Stephen23]

@Erik Sellberg: you can show your appreciation by voting for answers that help you :)