Dry eye diagnosis: Sorting out the puzzle pieces
TFOS DEWS II tells us that dry eye diagnosis can get surprisingly confusing and complex amidst all the things that mimic it, masquerade as it, and are "co-morbid" with it (i.e. other conditions you also have at the same time).
I was reminded of this particular issue repeatedly this week while on the phone with one person after another who seems to be experiencing dry eye symptoms, but also maybe ocular allergy symptoms, but doesn't think they have allergies, and oh yes they have a little bleph, and one of their doctors once told them they have a poor blink, etc, etc, etc.
I've excerpted below a couple of paragraphs from TFOS DEWS II Definition and Classification report. If it's just too heavy on the medical-speak, here's the bottom line:
Lots of things can have the same symptoms as dry eye without being dry eye
Lots of things may be happening at the same time as dry eye (the example given below is incomplete eyelid closure, but there are many others) as a result of which JUST treating dry eye won't work - you have to deal with the other things too.
Several years ago I sat in on a very nice presentation of Lipiflow to a group of doctors. A key TearScience salesperson said, and it always stuck with me: "If you have an incomplete blink, there's no way Lipiflow will fix your dry eye. It just can't." I wish every patient I know who's had Lipiflow had been told the same thing. Solutions are designed for specific problems, not for clusters, especially when the pieces are unrelated except for the fact that they all ultimately affect the tear system.
It's so important that we have the complete picture of our "ocular surface disease" - all the pieces of the puzzle, not just the dry eye piece. Successful dry eye treatment and management ALWAYS begins with getting a thorough diagnosis. It's particularly important during allergy season, because figuring out which solutions will help more than they will harm, or relieve more than they irritate, is not always straightforward. Don't let your eye doctor get away with the "just dry eye" line - educate yourself and go armed with questions to every appointment.
TFOS DEWS Definition and Classification report
7.2. Other ocular surface disease differential diagnoses
Ocular surface disease is the broad category that is considered to include a multitude of ocular surface conditions, some of which closely mimic or masquerade as DED, and many that can occur concurrently with DED . Because of this complexity and overlap, dry eye is frequently treated as a diagnosis of exclusion. The TFOS DEWS II Diagnostic Methodology report presents triaging questions , which can be used, in combination with clinical findings, to differentially diagnose other ocular surface conditions that may require specific management, and result in relief of signs and symptoms that might otherwise be attributed to DED.
It is important to note that many ocular surface diseases can be co-morbid with dry eye, thus a step-wise approach to management, with subsequent follow-up to monitor signs and symptoms is warranted. For example, symptoms and tear film changes commensurate with DED might well occur in a condition such as lagophthalmos, due to poor lid to globe apposition, preventing formation of a stable inter-blink tear film. However, resolution with dry eye therapies alone is unlikely to succeed, as the surfacing problem cannot be resolved without managing the lagophthalmos. The converse of this scenario is that restoration of lid-globe apposition through surgical management of the lagophthalmos has the potential to fully resolve the dry eye symptoms and signs without the need for dedicated dry eye therapies [, ]. Further research is needed regarding co-morbid ocular surface conditions that induce a secondary dry eye.
References in this excerpt:
 Wolffsohn JS, Arita R, Chalmers R, Djalilian A, Dogru M, Dumbleton K, et al. TFOS DEWS II Diagnostic Methodology report. Ocul Surf 2017;15:539574.
 Jones L, Downie LE, Korb D, Benitez-del-Castillo JM, Dana R, Deng SX, et al. TFOS DEWS II Management and Therapy report. Ocul Surf 2017;15:575628.
 Latkany RL, Lock B, Speaker M. Nocturnal lagophthalmos: an overview and classification. Ocul Surf 2006;4(1):4453.