Photophobia "not a single disease; it's a symptom," says distinguished eye expert

Shelby Ramsey

Special to the Village News

The medical term "photophobia" as it is written, is a misnomer read as "fear or dread of light."

Dr. Kathleen Digre, a distinguished neuro-ophthalmologist and former president of the American Headache Society and former president of the North American Neuro-Ophthalmology Society, provided more clarification on this topic.

Photophobia "is really a discomfort people have," Digre said. It is defined "as an abnormal sensitivity to light, especially of the eyes," such exposure "definitely induces or exacerbates pain."*

There are many causes that can lead individuals to have the symptom of photophobia. "Just like headache can be caused by different things; photophobia can be caused by different things," Digre said. Those who don't experience it, may be wondering what it's like.

Liken it to a beautiful, sunny summer day when you take in a matinee to see a new release. Fast forward just shy of two hours later as you make your way out of the theater and into the parking lot to your car. We all know how it feels to be met with the blazing sun, our eyes still adjusted to the dark movie theater auditorium, and feeling discomfort, perhaps constant blinking or shielding our eyes until we are re-adjusted to the daylight.

For those who experience photophobia, navigating that feeling is a much more frequent scenario – no movie theater required.

It is "intimately, likely inextricably, linked to pain sensation. The trigeminal nerve and its nuclei are the primary mediators of pain sensation to the head."*

"It's not a single disease. And this is really critical to understand because most people lump it all together into one thing; and it's not," said Digre.

Like other symptoms, patients should strive to work with medical professionals to find the root of symptoms they experience. Health can be likened to an intricate web.

"Migraine is the most common neurologic disorder causing photophobia."*

Research is far and few between on photophobia, but that just means the future findings have much room to provide ample clarity.

Digre, who is heavily involved in this area of research, explained the most recent advances in understanding photophobia.

A recent advance has been the identification of "the pathways that can lead to pain associated with light sensitivity." By "finding that there's a real anatomic pathway, from my point of view, is the most important advance we've made in the last 10 years," she said.

To paint a clear picture, prior to this finding, "Nobody understood why somebody could get it or what pathways existed," Digre explained.

The pathway involved in photophobia "starts in the retina with the vision seeing cells in the retina (neurons or ganglia in the retina) but there are non-vision seeing neurons too called Intrinsically Photosensitive Retinal Ganglion Cells (melanopsin) and this pathway is very old and it belongs to invertebrates (frogs, amphibians), so it's an extremely old pathway but it's in our retinas." This old pathway "doesn't see vision, but it senses light." From that point "it goes into the circadian rhythm center of our brains," she said. Digre noted that both this pathway and the visual seeing pathway, "connect with the trigeminal pathway in the brainstem and thalamus to cause pain and discomfort with light."

This advancement offers the evidence needed to underscore "nobody makes it up, it's a real pathway, it exists and it's been shown to be present," she confirmed. This is really important and comforting – it's real; your pain is real; your discomfort is real.

If you experience photophobia and aren't sure where to turn, Digre offered sound advice.

"First, get the right diagnosis, [which] is not an easy endeavor for many people," she said.

The reality of this is staggering, as stated in a paper she co-authored "showed that about a third of our patients that came to our eye clinic (who were children and adolescents) left without a diagnosis of the cause of their photophobia."**

The doctors we choose to treat us can make all the difference. If you are not already with the right choice for you and your health, I hope you find a provider who is.

As we know, being under-diagnosed or misdiagnosed can leave us feeling unsettled while we try to co-exist with our symptoms and health conditions.

Without having a 'starting point,' it can feel and be very tough to move in the appropriate direction. It also can deter individuals from seeking out a second opinion. We want to find doctors, solutions, and research that help us succeed, not knock us down.

There are at least three specialties that can be of great help to those navigating these issues:

· A neuro-ophthalmologist (who "is trained to at least know the different causes of photophobia"); you can find one at: https://www.nanosweb.org/i4a/memberDirectory/index.cfm?directory_id=3&pageID=3390

· A neurologist or provider who understand migraine (see: https://americanmigrainefoundation.org/find-a-doctor/)

· A cornea specialist who understands dry eyes

Digre shared the top three diagnoses for photophobia:

1 – Migraine: "Over 90% of people with migraine have photophobia"; "70% of the people with photophobia that we have in our study are women."

She underscored how helpful headache providers (neurologists) are for treating patients with migraine.

In clinic and research, in response to "What is your most bothersome symptom?", she said patients with migraine respond, "photophobia."

2 – Dry eyes: "Reduced visual quality of life with migraine is very closely aligned with dry eye symptoms." Digre explained that while individuals may have either low tear film or good tear film, dry eye symptoms can still be present.

3 – Traumatic brain injury: "Most of the people who have [experienced] a blast or traumatic brain injury also get photophobia," which remains after the initial blast/injury.

In addition to the above three, additional conditions associated with photophobia include*:

· Ocular inflammation (iritis, uveitis)

· Conjunctivitis

· Dry eyes

· Optic neuritis

· Papilledema

· Meningeal irritation (meningitis, subarachnoid hemorrhage)

· Fibromyalgia

· Inflammatory bowel disease

· Chronic fatigue

· Pituitary tumor

· Pterygium

In a chart review of 111 adults and 36 children that were diagnosed with photophobia, "The most common ocular condition was dry eyes, while their most common neurologic disorder was migraine."*

Asking Digre what she hopes will be the most prominent research finding on photophobia in the next decade was informative and reassuring.

"I am hoping research will help us come up with better understanding and better treatments," she said.

This means getting answers to big questions such as: "What is the mechanism that turns this photophobia on?" "What keeps it going?"

The roadblocks are there currently "because you can do MR scans and the brains look normal in these individuals," she explained. While MR scans provide no clarity, Digre said even though you can't "see something that's wrong ... something has deregulated and gotten turned on."

Of course, following that lead, understanding "How do we turn [photophobia] off?" she said.

This, in turn, should allow treatment options to unfold to provide relief for individuals.

Without these answers present day, treatments are approached in sectors. "We treat the migraine part of it, hoping that's going to make it better. We treat the dry eye component, hoping that's going to make it better," she said.

In a paper Digre co-authored, she wrote, "It is unknown whether dry eye treatments will improve dry eye symptoms, improve visual quality of life, or reduce headache severity."***

In response to what she would like those who suffer from photophobia, migraine, and/or eye pain to know, Digre confidently responded: "There is hope."

"We are gaining more knowledge," she said.

"We are training medical students, residents in ophthalmology and neurology," Digre said. The "curriculum that we are developing for photophobia is going to be really helpful because it's just going to give [medical professionals] a structured pathway of how you make the right diagnosis."

It all starts with the right diagnosis. Once we know what condition, symptom, illness we are dealing with, the better suited we are to be in the right medical professional's hands, learn how to manage it, and understand what treatment options are available or will become available.

Digre said the current focus is "Hope, research, and education."

Dr. Kathleen Digre is distinguished in the field of neurology and neuro-ophthalmology at Moran Eye Center. She serves as Chief, Division of Headache and Neuro-Ophthalmology at University of Utah and previously held the position of President of the American Headache Society and North American Neuro-ophthalmology Society. She is listed in Best Doctors of America.

*Digre, K. B., & Brennan, K. C. (2012). Shedding light on photophobia. Journal of neuro-ophthalmology: the official journal of the North American Neuro-Ophthalmology Society, 32(1), 68–81. https://doi.org/10.1097/WNO.0b013e3182474548

**Buchanan TM, Digre KB, Warner JEA, Katz BJ. The Unmet Challenge of Diagnosing and Treating Photophobia. J Neuroophthalmol. 2022 Mar 25. doi: 10.1097/WNO.0000000000001556. Epub ahead of print. PMID: 35427241.

***Ozudogru, S., Neufeld, A., Katz, B., Baagaley, S., Pippitt, K., Zhang, Y. Digre, K.B. (2019). Reduced visual quality of life associated with migraine is most closely correlated with symptoms of dry eye, research. Headache 2019 Nov;59(10):1714-1721. doi: 10.1111/head.13662.

Watch for Part 2 of this series in a future issue.

Shelby Ramsey is the author of the blog, thehonestmigraine.com, which also features interviews with patients and medical experts.