Retinal migraine causes temporary blindness or visual disturbances in one eye. Usually, these symptoms precede a headache, but not always.
Some practitioners use the term ocular migraine to refer to retinal migraine, but strictly speaking, the retinal migraine is one of two subtypes of ocular migraine. The other type of ocular migraine is migraine with aura, in which the visual disturbances that come before head pain affect both eyes.
The difference is that in retinal migraine, the vision symptoms are coming from the eye, while in migraine with typical aura the vision symptoms are coming from the brain. So with retinal migraine if you look through the right eye and close the left eye, you see twinkling lights but when you look through the left eye and close the right eye your vision is normal.
There are no diagnostic test for retinal migraine, and no recommended treatment other than usual treatment for migraine. In addition to a neurologist, an assessment by an opthamologist may be recommended to rule out other eye conditions.
Read more about retinal migraine at the American Migraine Foundation.