Myelinated nerve nerve fibers have a whitish look as they emerge from the optic nerve in the eye. Myelination is like insulation around electrical wires. That myelination exists on the nerves when they exit the eye, but in the eye they are unmyelinated. Sometimes the myelination will extend in to the eye. It doesn't cause any problems.
Vitreoretinal tuft is a traction on the retina from the vitreous bag that fills up the inside of the eye. As this bag pulls on the retina, it can sometimes be adherent to the retina in a localized place and pull the retina up a little. A small percentage of these become retinal tears, which can then turn in to detachments which would cause loss of vision. Therefore they need to be watched with dilated eye exams closely.