One of the most troublesome symptoms of PSP is photophobia. That sounds like a psychiatric condition, but it’s when bright light is uncomfortable or even painful, and it occurs sooner or later in nearly everyone with PSP. In a few, it’s one of the first symptoms, manifesting in some cases as difficulty watching a brightly spot-lit performer on an otherwise dark stage and progressing to an intolerance even for standard indoor lighting.
The explanation that I’ve long accepted starts with insufficient blinking, then drying of the surface of the eye, then inflammation, then pain when the pupil attempts to constrict to light. But I’ve recently learned that it also may be a direct neurological effect of the PSP disease process. https://pubmed.ncbi.nlm.nih.gov/18328771/ Supporting this theory is the observation that photophobia is a very consistent symptom of benign essential blepharospasm. That’s where the eyes blink or clench shut involuntarily, with no other neurological issues. Blepharospasm also occurs as a very frequent component of PSP, suggesting that blepharospasm itself, whether part of PSP or not, includes photophobia without implicating eye surface drying.
Whatever the cause, photophobia can be a very early and important feature of PSP. But someone with PSP experiencing photophobia should still look for other, more easily treated, causes. An article by Dr. Thomas Buchanan and colleagues at the University of Utah reviews the diagnosis and treatment of photophobia in the Journal of Neuro-Ophthalmology. (I know you all await each issue eagerly.)
They reviewed the records of every patient with photophobia seen at their center over a 9-year period, finding that 10 patients (9% of the 111 adults) had PSP. The only disorders accounting for larger percentages were migraine (54%), dry eye syndrome (36%) and eye trauma (8%). (These total more than 100% because some patients had more than one cause listed by their physicians.)
The article provides a thorough list of disorders causing photophobia. I’m not going to define these for you, but I suggest you look through the list, hopefully with the advice of your doctor, as some of them have specific treatment. Of course, in the population of those who already have PSP, the likelihood of any of these other conditions as the cause of their photophobia is very low.
This list is adapted from: Buchanan TM, Digre KB, Warner JEA, Katz BJ. The unmet challenge of diagnosing and treating photophobia. Journal of Neuro-Ophthalmology: 3/25/2022. 10.1097/WNO.0000000000001556
Causes of Photophobia
Seeking a treatable primary cause is all well and good, but that takes time, so aggressive treatment at the symptomatic level is the place to start. The best shaded glasses for photophobia aren’t standard, green sunglasses, but FL-41 tinted glasses. Those are rose-colored, and you’ll just have to endure jokes about your new outlook on life. If for some reason you find the green glasses more comfortable, don’t wear them indoors, as your eyes will adapt to the dark and become extra painful when you return to the outdoors.
Just in case your photophobia is caused by eye drying, lubricant drops, especially those with forms of cellulose, may provide relief. More aggressive measures include certain medicated eye drops, gel tables inserted in the lower lid, or petrolatum-based lubricants. Surgical options are available as well, though none of them has been formally tested in people with PSP.
There’s a specialty, believe it or not, called “neuro-optometry.” Those folks are usually easier to get an appointment with than a general ophthalmologist or neuro-ophthalmologist and may be more comfortable managing chronic, PSP-related problems like photophobia. Furthermore, they don’t do surgery themselves, so they are a good source of unbiased advice on that score.