With Oliver, painful eyes are his main symptom, caused by pressure from his greatly dilated ventricles. His whites are always red and he is light sensitive because the pressure behind the eyes interferes with the functioning of his pupils, which close slowly and not completely. As with us if we go out without sunglasses or a hat in strong light (for Oliver mainly, but not entirely, strong sunlight - bright white cloud can also be difficult), we can get a headache and start squinting in an effort to protect our eyes. Oliver doesn't even need to be out in it, he can start squinting even if he is in the shade looking out at bright light, or indoors looking at the window.
One thing I do find helps Oliver if he starts whimpering in his sleep when he is lying straight on his tummy with his jaw on the floor, is to roll him gently over onto his side, so that the pressure created by the CSF isn't directly behind his eyes. Having his jaw pressed to the floor seems to send pressure up through his skull, which meets the pressure from behind the eyes and makes things worse. You might find your Monster is more comfortable if you roll her over so that she is not lying on her bad side and the CSF pressure moves away to the other side of the skull.
If you want to take Monster out on the days when her eye is hurting, a sun hat is a great help (Oliver has a snazzy tan cotton baseball cap), or even doggles (Oliver has a pair but hasn't needed to use them so far). Oliver's sun hat is actually Great Dane size! I have to tie a knot in the elastic that goes under his chin, but this size gives him a long and wide soft brim to shade his eyes and it works well.
Kate, Oliver and Aled