Complement questionnaires with targeted dry eye testing
This clinician recommends screening all new patients to catch the disease early.
Appropriate use of advanced technology diagnostics can provide objective data that is useful for understanding the health of each patient’s tear film.
Fundamentally, the principle benefit of dry eye diagnostics is that they enhance the clinician’s opportunity to recognize ocular surface issues at an early stage and intervene appropriately to avoid the development of chronic and detrimental sequelae, which is beneficial in light of evidence suggesting a demographic shift in dry eye. Eye care providers may think of an older, postmenopausal woman as a typical dry eye patient, but studies are showing that patients as young as 10 or 11 years manifest meibomian gland changes, suggesting that meibomian gland dysfunction can be a precursor to dry eye (Moon et al.). These data go hand-in-hand with evidence showing a dramatic change in the visual demands of patients, including pediatric patients (Rosenfield).
Downside of dry eye testing
Despite the benefits of advanced technology, these diagnostics should be used with care to maximize the output. It may be tempting to throw every piece of testing at a patient with unspecific signs of ocular surface disease and sort through the readouts to determine the cause; however, a shotgun approach tends to yield minimal benefit. At the same time, there is no singular test to definitively diagnose dry eye, so testing should be used to enhance the findings of the clinical examination.
In my clinic, I have found the Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaire to be a useful starting point and an excellent screening tool for all new patients. A score higher than 8 will trigger my staff to utilize additional diagnostic modalities to better understand the health of the tear film. For example, tear osmolarity testing (TearLab) is incredibly important for assessing dry eye and it is one of the first tests we perform in our clinic, but it cannot be the sum total of the workup. A change in osmolarity of the tear film either precedes or can trigger inflammation, so it is an index of the tear’s quality.
While hyperosmolarity may indicate an inflammatory process, it does not diagnose its cause. Tear inflammation may be driven by one of two distinct pathways, mediated either by TH-17 (which leads to activation of matrix metalloproteinase 9 [MMP-9]) or by TH-1, which is characterized by its association with interferon gamma. Thus, MMP-9 testing, if performed, may yield a false negative if the mechanism of inflammation is related to the TH-1/interferon-gamma pathway.
On the other hand, in light of the findings by Jackson and colleagues, positive lissamine green staining or a report of waxy tear film that suggests mucin layer insufficiency and attendant loss of goblet cells may detect what is missed by a MMP-9 assay, the IFN gamma pathway.
Tear Lab is working on a new dry eye chip that will include more biomarkers in addition to osmolarity, which might be useful for sorting some of the confusion. For now, what this suggests is that advanced testing should be used with discretion and as a piece of the entire clinical picture.
A case for baseline meibography
These tools each have diagnostic value, but they are also important for following patients over time. I am actually an advocate for wider use of dynamic meibography in more patients to help establish a baseline of the structure of the glands. Much like we do in glaucoma, where optic nerve findings are used to help diagnose, stage and follow the health of an eye, functional correlates of the meibomian glands could be of tremendous value in dry eye assessment. I try to capture a baseline meibography on all patients for potential comparison of morphological changes later.
Four devices are currently available for reviewing the morphology of the meibomian glands: LipiView and LipiScan from TearScience, the Oculus Keratograph and Meibox from Box Medical Solutions. Each mechanism has its pros and cons, the merits of which are open to debate. What they have in common is that they provide a means to capture an image of the glands’ structure, with implications for screening, diagnosis, staging and following patients.
Recognizing impacted glands would also help identify those individuals who might benefit from expression using the LipiFlow procedure. The Meibomian Gland Expressor (MGE) from TearScience is a valuable tool for evaluating meibum.
When I introduce the procedure to patients, I do not promise symptomatic relief (even though this is likely) and, instead, focus on LipiFlow as a mechanism for anatomic preservation. In many patients, a LipiFlow treatment is like reopening the flood gates to allow the natural physiologic meibum to coat, lubricate and protect the ocular surface.
More in the pipeline
It is truly an exciting time in dry eye, and thanks to promising technology in the pipeline, the future looks even more promising. One technology I am looking forward to implementing is the TrueTear device (Allergan) to stimulate the trigeminal nerve, which innervates lacrimal glands, goblet cells and meibomian glands. The concept of neurostimulation offers a novel mechanism for treating dry eye that may have short- and long-term benefits, as there is suggestion that the device affects restoration of the lacrimal function unit. It may prove to become a helpful adjunct after meibomian gland obstruction is removed and glands are evacuated with a LipiFlow treatment.
TrueTear recently received FDA approval, and initial feedback is quite positive.
Diagnosis is key
The fact remains, however, that we can only treat what we are able to identify. The thoughtful use of questionnaires to identify those in need of additional workup is a helpful first step to directed testing including osmolarity and meibography.
Dry eye is becoming more and more prevalent, and eye care providers have a tremendous opportunity to catch the disease early, intervene and help patients avoid chronic disease and the eventual development of altered tear function. It is time we cast a wider net to capture more patients and follow that with the thoughtful use of advanced technology to gain a more complete understanding of the health of the tear film.
- De Paiva CS, et al. Mucosal Immunol. 2009;2(3):243-253;doi:10.1038/mi.2009.5.
- Jackson DC, et al. Invest Ophthalmol Vis Sci. 2016;57(11):4824-4830;doi:10.1167/iovs.16-19757.
- Moon JH, et al. J Pediatr Ophthalmol Strabismus. 2014;51(2):87-92;doi:10.3928/01913913-20140128-01.
- Rosenfield M. Ophthalmic and Physiol Opt. 2011;31(5):502-515;doi:10.1111/j.1475-1313.2011.00834.x.
- Yoon KC, et al. Invest Ophthalmol Vis Sci. 2007;48(6):2561-2569;doi:10.1167/iovs.07-0002
- For more information:
- Scott Schachter, OD, specializes in ocular surface disease, is in private practice in Pismo Beach, Calif., at Advanced Eyecare and serves as a Vision Source administrator for the central California coast. He can be reached at: firstname.lastname@example.org.
Disclosure: Schachter serves on the advisory board for Allergan, BlephEx, ScienceBased Health and Sun Pharma and is a speaker for Allergan and Bausch + Lomb.