The NeuroOpthomolgist said something interesting about the eyes being our window to the brain. After the examination he noted my husbands eyes do not move down in a straight vertical way but rather they take a slow curved staggered trajectory south and they wiggle back and forth when they go up.
Then he said your husband's difficulties with bright lights especially florescent lights, flickering lights and oncoming headlights are a tell tale sign of photophobia.
He noted the eyelids squeezing close to shutting when reading and the tilting backwards of the head to help keep the eyelids open. This is Eyelid Apraxia.
Together these signs he said are not typically found in Parkinson or MSA or CBD, these are optical signs they find in PSP.
I told him my husband gets dizzy and he said yes the eyes are giving his brain slow information.