In regards to adults and children alike, most people assume that because someone can see clearly, their eyes are healthy.
While most diseased eyes typically present with a visual issue, there are a myriad of things that can be affecting somebody with no visual symptoms. Retinal detachments are the pathology that my mind drifts to first, but I've even seen systemic issues like a choroidal melanoma present asymptomatically, or without symptoms. Hypertension, diabetes, early cataracts, glaucoma, and even pituitary gland tumors are all things that we are able to detect during the course of an eye exam. I've had at least two patients tell me that their eye doctor detected their pituitary tumor.
With children, things become a little more tricky. During a pediatric exam, a child is screened by checking the vision in both eyes individually. What are not checked are the movement of the child's eyes, the ability of the eyes to function properly when reading (such as tracking with the eyes), and the periphery of the eye. If a child has a refractive disorder or vision problem that is missed by the pediatrician and not caught by an eye doctor until after the age of 8, the problem may never be fully correctable (termed amblyopia).
Retinoblastoma is one of the most common cancers in children. There are inherited and non-inherited forms. The tumor typically starts growing in the periphery of the eye and would most efficiently be discovered with a dilated fundus examination performed at a routine eye exam.
On the right, this picture shows the typical view of a direct ophthalmoscope (in white) which pediatricians use to check a child's eye. Everything else is not being seen.
The picture above shows a child with retinoblastoma (white on the bottom, underlying the blood vessels) that would be missed assuming only the optic nerve would be evaluated by a pediatrician. The vision in this child would likely be unaffected.
With the school year ending and a new school year approaching, there is no better time for you AND your child to have a full eye exam.