AerocatS2A
You need to carry a second pair of lenses.
Sorry, a bit long winded, but see my bold type at the end!
Civil Aviation Safety Regulations 1998 (CASR)
67.150
1.36 Can read (with or without correcting lenses) an N5 chart (or its
equivalent) binocularly at a distance that he or she selects (in the range
of 30 to 50 centimetres), and can read an N14 chart binocularly (with or
without correcting lenses) at a distance of 1 metre
Note A person who needs correcting lenses to meet this criterion must have
the appropriate lenses available while carrying out duties under a relevant
licence — see regulation 67.200
67.200
Conditions applicable to certain medical certificates —
correcting lenses
(1) In addition to any other condition imposed by or under this Part, a
medical certificate issued to a person who needs correcting lenses to
satisfy the requirements of item 1.36 of table 67.150, item 2.36 of
table 67.155 or item 3.34 of table 67.160 is subject to the conditions
set out in subregulations (2) and (4).
(2) The person must have those correcting lenses available for use while
exercising the privileges of a licence for which the certificate is
required.
Civil Aviation Safety Regulations 1998 (CASR)
CASR – 1st Edition – January 2003 Office of Legal Counsel
New Page – Amdt No. 3 – 3 September 2003 Civil Aviation Safety Authority
Part 67 — 39
(3) If the person is the holder of, or an applicant for, a licence for which
he or she is required to meet medical standard 1 or 2, the correcting
lenses may be a pair of spectacles or a combination of contact lenses
and a pair of spectacles.
(4) A person to whom subregulation (3) applies must have within reach,
while he or she is performing duties essential to the operation of an
Australian aircraft during flight time, a spare pair of spectacles for
each pair of correcting lenses that he or she requires to meet the
relevant medical standard.