Tears or nerves? Nerves or tears?
There was a fabulous session at AAO called “Evaluation and Management of Painful Dry Eye Symptoms: Nerves vs Tears” with the the perfect team: Anat Galor, Debbie Jacobs, Todd Margolis, Pedram Hamrah.
It’s a complicated time for the whole neuropathic pain discussion.
On the one hand, we’ve come a long, long ways from the days of Dr Jacobs’ and Perry Rosenthal’s “Pain without Stain”, the seminal study that thrust the question of corneal pain into a much-needed broader discussion amongst experts and which has led to so much excellent research. We have TFOS DEWS II Pain and Sensation report from 2017. We have language to talk about central and peripheral neuropathic corneal pain. We have a small handful of experts around the country that can diagnose and treat patients.
On the other hand, it’s nowhere near the mainstream. I think it’s safe to suggest that the majority of people with corneal pain - especially if it’s less than catastrophic, but still serious - are still getting ignored and treated as simply having dry eye.
And… on yet another hand - and this is a key reason why the tear vs nerve session at AAO was so interesting to me - we may have the opposite problem to a degree: We are seeing both doctors and patients over-generalize this neuropathic pain animal. Neuropathic pain, or corneal neuralgia, in some specialty practices may be turning into the diagnosis-of-elimination of choice: It doesn’t look like you have bad enough dry eye to explain your pain, therefore you have neuropathic pain. Or something along those lines. Meanwhile, patients on social media are going way overboard with self-diagnosis of neuropathic pain.
So there’s a little background about why this entire pain session was a joy to listen to. Science and sense, from the best brains, at the podium…. ahhh such a pleasure.
Now, I’ll just take a random wander through some of the many things I enjoyed in this session.
What is pain?
And why aren’t we using this term more? We really need to be!
Dr Galor introduced this session with the IASP definition of pain:
an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
- International Association for the Study of Pain
I think it’s safe to say that nearly all “dry eye” symptoms fall into that definition of pain. We don’t have to reserve that term for only the extreme suicide-inducing versions of pain. It is equally valid across the pain spectrum.
Dr Galor talked about different types and sources of pain. The most important take-home from that is simply that pain can be (a) from something visible going wrong on some part of our ocular surfaces (eye and inside of eyelid surface), or (b) not. The huge challenge this presents to eye doctors is that the patient is reporting symptoms and the doctor sees something that explains it, they can believe the symptoms. If the patient is reporting symptoms and the doctor doesn’t see an explanation, it’s much harder to believe.
So (my commentary, not hers) that leads us to the questions of (a) are they looking for all the right visible things, and (b) do they know the pain may be real and yet coming from something that is not visible during their routine exam.
Those are two big medical knowledge gap areas that have affected care for many of us in the “dry eye” community. If you are not seeing a doctor who has very strong knowledge of BOTH, then you may not be getting the validation and help you need. And honestly? There aren’t very many of them.
Anyway, back to Dr Galor. Here’s the bottom line for what doctors are supposed to do:
“Our goal is to be a detective: Why are the nerves unhappy?”
- Dr Galor
By “unhappy nerves”, she doesn’t mean neuropathic pain specifically. She means pain from obvious causes, pain from subtle causes, and pain from causes you might never guess unless you had just the right knowledge and had some sophisticated machinery to help figure it out.
So… if your eyes hurt a lot, an important part of your path is finding a doctor that has detective training.
Differential diagnosis matters
One of the biggest problems in the “dry eye” (or rather ocular surface disease) world has been, is, and will remain, less common diagnoses that fly under the radar.
(If that didn’t sink in, please read it again.)
It’s important to not make the leap too quickly from “nothing to see here” to “must be neuropathic”. There might well be “something to see here” that simply has not been seen or has been hiding in plain sight. It happens. Every really good specialist can rattle off at least half of dozen of these that they see regularly. We’re talking about patients who have been to many appointments and sometimes seen many doctors, possibly including cornea specialists, but still had something overlooked… that mattered.
Dr Margolis sped through so many of these that I couldn’t even jot them all down, but some of the ones on his hit list were contact lens abuse, SLK, Salzmanns Nodular Degeneration, lid imbrication syndrome, and referred pain - that latter was very interesting, he discussed referred pain from things like sinusitis, extraocular muscles, face, lids, forehead… who woulda thunk.
Language matters
The language you use changes how you think.
Dr Margolis
Dr Margolis sang from one of my favorite song sheets in this session: He talked about how the language you use changes how you think, and on that basis, he does not use the term “dry eye”. He uses “ocular surface disease” for the disease part, and “patient pain” for the symptom part.
Now, if only we could replicate that across an entire profession, life in the land of “dry eye” would change substantially.
He also recognized that when patients say their eyes are “dry”, that is a learned language and it means nothing. He insists that instead, they report their actual symptoms.
Dr Jacobs also described banning “dry eye” from her practice. (I wonder if we could encourage all our doctors to do so as well?) She does not allow this term in her contact lens patients either - it’s contact lens intolerance, not dryness.
Diagnosing and treating: A few random highlights
I’m not going to describe in detail what these doctors told of their diagnostic procedures, or treatments either. Every doctor is different and there’s just way too much to share. But I want to share a few things that stood out to me. These are the sorts of things that tell us about what kind of doctor can perhaps be the most help to us.
Dr Margolis did a great job of describing how to be a very observant eye doctor by watching carefully from the moment you walk in the door and during the initial conversation: How much exposure are the patient’s eyes seeing? What’s their blink rate? Are they touching their eyes with a tissue? Are they sensitive to light? Are there signs of contact dermatitis or rosacea? This is a level of detail I would love all us patients to have access to!
Topical anaesthetic drops have become a pretty well accepted way to determine whether the pain is coming from the eye surface or not, but it’s important to keep in mind that it’s not a binary question, as Dr Hamrah pointed out in his presentation, describing a “full response, partial response, or no response” to the drops and also going on to explain that the partial response is the most common, meaning answers are nuanced, not straightforward yeas or nays.
Again on the point of topical anaesthetics: I think that people sometimes forget the corollary - that if a topical anesthetic doesn’t help at all, then neither will any other topical treatment.
I enjoyed Dr Hamrah’s take on the goal of neuropathic pain treatment where he gave the example of getting people down from an 8 to a 4. Both in neuropathic pain, and in “symptomatic” ocular surface disease, and of course all the overlap situations, incremental improvement is what we’re aiming for. To me, that means two things: (a) avoiding binary, “just fix it” type thinking, and (b) making sure you have a METRIC that you’re employing regularly so that you actually KNOW whether you’re feeling better or not. I just don’t really believe most of us know the difference between an 8 last February and a 6 today and a 7 in three weeks’ time. Chronic pain has poor memory. Measure, measure, measure. You may find yourself surprised.
Migraines, migraines, and migraines: Dr Hamrah had a long list of common neuropathic pain “co-morbidities” (stuff you might also have) and migraines were at the top of the list. I’ve had migraines on the brain, pondering how many times migraines came up in ocular surface disease contexts during the conference.
With pain, we have to get ahead and stay ahead of things. Quitting treatment is a very common problem. Dr Jacobs discussed the pattern where people with neuropathic pain really don’t want to use the meds they do, so when they feel better, they quit, then they get worse. It sounds like a no-brainer, but it’s totally understandable that people do this… just unfortunate how it comes back to bite them. It’s a bit like how with more classic “dry eye” people may feel better in the summer so they slack off of everything because they’re not as symptomatic, then they really get punished for it in October when the humidity drops and the heat comes on.
Another quote I enjoyed:
Try onion goggles: If it’s not improving, there’s nothing I can do topically that will improve it.
Dr Margolis
In my original notes from this talk, I wrote “i love this man!” below that one. So few doctors know about onion goggles, fewer yet would even consider using them in any way diagnostically or to guide further treatment. This is smart. Too many doctors seem to be exclusively aware of drugs and devices. The fact is, with ocular surface pain, stimulating hypersensitive nerves is a big deal and insulating your eyes from those assaults is a big deal. This needs to be better recognized. Physical barrier protection matters.
Case studies: Don’t leap to conclusions - in either direction!
Now we come to my favorite part of the talk. They went through a lot of case studies and asked the attendees if they would diagnose neuropathic pain or not. It was FASCINATING, I learned a lot and it also confirmed a lot of what I already believed about too many assumptions being made and not enough painstaking elimination. This is a disease area that requires time and thought, and the doctors willing to do that (and whose business model allows them to) are the ones that will serve us the best.
We know we don’t know what’s going on, so we’re happy to say it’s nerves
Dr Jacobs
I love this quote. It’s been an observation/fear of mine for some time that we can be in a little too much of a hurry to dismiss all unexplained corneal pain as neuropathic. Dr Jacobs pointed out situations where test results and classic, expected ocular surface disease signs were not present but it turned out there was a non-neuropathic explanation of pain, such as ocular surface exposure from lid abnormalities. She also used a phrase that makes great sense: “nociceptive pain… [i.e. pain from disease or other visible stuff going on] …with neuropathic amplification [i.e. when misbehaving nerves make it feel worse than it looks like it ought to feel]”. I suspect there’s quite a lot of people in that category when it comes right down to it.
Here’s another classic quote:
Patients often have multiple potential contributors. You have to pick the one you’re going after.
Dr Galor
I think that there’s a lot of awareness of multiple contributors, but I don’t think we patients realize the challenge of making the judgment call about which one, or ones, to go after - which ones matter. You might have 5 different things wrong. But which one is actually contributing most to your symptoms? That’s not by any means obvious. It’s a pretty big deal in the so-called dry eye world.
There was much, much more, but I have to call it a day. I am just so thankful there are such terrific researchers working on this problem for us and teaching everything they learn to those of their colleagues that are interested and care.