So, I have really bad eyesight (short-sighted): without my glasses, I can't read text unless it's near. So can I be a commercial pilot?
According to the Civil Aviation Authority of Malaysia's medical standards:
(c) Distant visual acuity, with or without correction, shall be:
(1) in the case of Class 1 medical certificates, 6/9 (0,7) or better in each eye separately and visual acuity with both eyes shall be 6/6 (1,0) or better;
(2) in the case of Class 2 medical certificates, 6/12 (0,5) or better in each eye separately and visual acuity with both eyes shall be 6/9 (0,7) or better. An applicant with substandard vision in one eye may be assessed as fit in consultation with the DCA subject to satisfactory ophthalmic assessment;
(3) applicants for an initial Class 1 medical certificate with substandard vision in one eye shall be assessed as unfit. At revalidation, applicants with acquired substandard vision in one eye shall be referred to the DCA and may be assessed as fit if it is unlikely to interfere with safe exercise of the license held.
The key words appear to be "with or without correction", i.e. it's completely fine if you wear glasses to correct your vision. That seems to be standard around the world, e.g. the US standards also allow correction.
This depends on your jurisdiction but the FAA will allow it so long as your eyesight can be corrected (i.e. with glasses) to 20/40. You can find the full vision requirement here.
20/40 or better in each eye separately (Snellen equivalent), with or without correction, as measured at 16 inches
I am in Malaysia as well.
Your visibility problems may not stop you from getting a CPL/multi engine/IR license but once you've got that in hand you need to pass thru the airline interview.
Currently the job market for pilots in Malaysia is a bit soft in that there are more pilots than jobs, as such airlines can pick and choose. If you have two guys with the same license you will definitely choose the one with better health, better academics etc.
Not trying to kill your dreams but this is something you really need to think about before you pursue a commercial license.