Is it necessary to have your eyes dilated when having an eye exam?

Depends: It depends what your are looking for, what the problem is that you are being examined for and the doctor and his or her preference. Often the doctor can see what is needed without dilation. However, a thorough and comple exam will require dilation and a good look at the back of the eye (retina). There are many other reasons to give.

Usually: A comprehensive eye examination requires dilation to rule out disease in the back of the eye. Although a fair amount of the eye can be seen without dilation, there are areas of the eye that would not be properly evaluated. If you are seen annually or every few years, it is best to be dilated at these visits. It would otherwise be like having a general health exam without listenting to your heart!

It's a good idea: Without dilating the eyes, doctors can see only the central 10% of the eye. There is a lot more territory out there that is only visible when you dilate the eyes. It is easy to miss tumors, retinal detachments, and other serious conditions without a dilated retinal exam.