Hi Mom Allison
In a child or infant, little optic nerves are much more serious than large optic nerves. Little optic nerves are called hypoplastic and often do not see well. Small eyes have small optic nerves (hypo-plastic). Optic nerves (like people) come in different sizes with the average being about 1.5 mm in diameter. So there is a variation in size that occurs in perfectly normal eyes. Larger than normal optic nerves could occur due to myopia, large eyes, buried drusen, abnormal swelling or inflammation (papillitis and papilledma). The optic nerve can appear larger than normal due the coloration around it (conus, retinal pigment showing).
On the other hand he may be referring to the size of the optic cup, which is a depression on the optic nerve that varies from completely flat (no cupping) to totally cupped in end stage glaucoma.
It's very important that the "doctor" telling you this is a physician (ophthalmologist Eye MD) and not a non-physician, limited care provider (optometrist). If you saw an optometrist the first thing I would suggest is that you make an appointment with a comprehensive ophthalmologist or pediatric ophthalmologist right away. Also if you saw an optometrist get copies of your child's eye exam and take that record in to see the ophthalmologist. This is the type of problem that should be evaluated by a Doctor of Medicine (MD).
JCH III MD Disease and Surgery of the Eyes (Eye MD)
Thank you for your help, My child is seeing an ophthalmologist Eye MD but I am not sure if he spoke of the nerve or the cup, I have a call into the office to go over the appointment. I will post what I find out