This is interesting... since Singapore is one of the cities with most eye problems...
and we have varying eye test results... I guess this is something the Singapore authorities should look into... and among those I know... this is not the first time I hear people complaining about problems with adapting to a prescription.
I supposed the one done at Lasik Clinic is the most accurate? since it is for Lasik purpose...
All the test are about the same... first look into a telescope kind of device to determine power by the computer.
Then for manual test, use a frame where lens can be inserted. Some insert the lens and some just hold it in front of the frame to see the difference.
I'm not sure what is meant by "the best seeing line"... but I guess I could see the 2nd smallest line...
The one done at Lasik Clinic has the dot test. The other 2 don't have.
With this you are wrong. Eye diseases CANNOT be detected by determining the POWER ALONE. Eye diseases can only be diagnosed by a whole series of test. History of patient, Refractive power, Ocular health check, Fundus check, Visual field, EYE PRESSURE, etc. ALL OPTOMETRIST must do all the test at each visit. But most optical shops bosses do not allow these tests because it is not cost effective.
Opticians need to take patients history before proceeding with refraction of the eye power. IF patients have not done a full check with an optometrist or ophthalmologist within a year, THE optician MUST reccommend that the patient have a complete eye examination done before glasses can be prescribed and also tell the patient that HE/SHE is NOT conducting a FULL eye exam.
MOST OF THE TIME, tests are not done and no patient complains to the authorities. WHY? because singaporeans DO NOT know what optometrists and opticians HAVE TO DO at each visit.
Best seeing line means the visual ability usually recorded as 6/6, etc.
fluctuation of 50 degrees between eye tests is a very common fluctuation between tests.