Testing babies' eyesight

[honkytonkman]

As far I can work out, doctor's can test a baby's eyesight without all the usual "Is that better or worse" etc.. Why don't they test adult's sight like that ? It would eliminate the possibility of incorrect answers and thus the wrong prescription. Surely there is a method for measuring the refraction of an adult's eye?

[annie0000]

They kind of do that with my son who is 8 and is short sighted - he is on a 3 monthly eye test cycle as his eyesight has been getting rapidly worse and he needs a new prescription quarterly. Initially he did all that reading the lines and the usual better or worse thing. But the last couple of times he has had to stay completely still while they have shined a light in his eyes while changing the lenses on the testing frames until they are happy that they have the prescription correct, then they get hime to read the bottom line on the chart to check.

[Lil O'lady]

Optician's can look into the eye and measure the distance from cornea to retina, and assess the overall eyeball shape, which contribute to the quality of eyesight, so they can tell if there is something obvious about your eyesight that calls for correction.
But that won't correct for finer detail, so it's simpler and more effective to be able to ask the customer how different combinations of lenses affects their sight..
An ongoing dilemma is that opticians aim to give you 20-20 vision - but in nature, most people don't have perfect vision, just 'good enough' eyesight that allows them to do what they need. Modern life with its roadsigns, reading, computers etc demands far more 'corrected' vision that nature gave us.

[honkytonkman]

Two excellent answers! :) Thank you so much!