A few people have been asking me about online refractions and here are my thoughts
1) An online refraction will never replace an actual refraction from an eye care professional. An online refraction essentially is a finely tuned auto-refraction. It gives you a prescription, but it is a prescription based on one measurement. An optometrist during an exam gathers information such as visual needs and demands, your age, your history of eyeglass wear and your chief complaint, and then performs a refraction and then compares that with your old prescription, your visual acuities, and the auto-refractor results along with the rest of your history to determine the final prescription.
2) Online refractions unfortunately do not screen for ocular disease. One online refraction site called opternative even has a disclaimer saying if you have any eye diseases or medical conditions you should not use their program. The problem is, how would you know? Many diseases that affect the eyes such as glaucoma, diabetes, hypertension, brain tumors, multiple sclerosis among others are silent and therefore would be missed by an online refraction when they otherwise could have been evaluated and treated appropriately by an eye care professional.
Here a few things to keep in mind when purchasing eyewear online
1) A recent study done by ordering 154 pairs of lenses from online vendors showed that....
a) 29% of childrens glasses and 23% overall failed impact resistant testing.
b) 45% of prescriptions ordered had the wrong prescription or were given the wrong lenses (single vision instead of multifocal).
c) 29% of the lenses were missing anti-reflective coatings and anti-scratch coatings that the patient had paid for.
Buyer Beware indeed.