Hi there,
Unless someone here can list the eyesight requirements for a class 1 medical (is there a further requirement for ATPL holders?), your best bet is to see an aviation medial examiner in the UK, as 3 Holer suggests.
The following is a link from the Australian Civil Aviation Safety Authority (CASA) which lists a number of UK based doctors authorised to conduct medicals for an Australian licence:
http://www.casa.gov.au/avmed/damedis...on=Overseas#42
Best of luck,
Zap