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Ocular surface specialist gives pearls on dry eye management in TFOS DEWS II era
The ocular surface is like an orchestra in which the weakest instrument has to be detected and rejuvenated to re-establish integrity and harmony.
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The 150 specialists from 23 countries who joined their efforts for 2 years to produce the Tear Film and Ocular Surface Society Dry Eye Workshop II report rendered a tremendous service to all eye care professionals, according to John D. Sheppard, MD, MMSc, a leading ocular surface disease specialist.
“TFOS DEWS II made a step forward in the understanding of the mechanisms involved in dry eye, which will guide us to better treatment. The complexity of the disease is reflected by the complexity of the report, which, filtered down to the essential, was expressed in the new definition: Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles,” Sheppard said.
The difference from the previous definition initially may not appear to be so great: “Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface.”
“In both definitions there is tissue damage and inflammation, and multifactoriality is perhaps more clearly mentioned in DEWS II. However, DEWS II no longer calls it ‘a disease of the tears’ and significantly adds the neurosensory component,” he said.
Tears, in terms of quantity, quality, durability and tenacity, are in DEWS II a reflection of what is going on with the ocular surface and its seven major components, first named together by Richard Thoft in 1978: the corneal epithelium, the conjunctival epithelium, the lids, the lacrimal functional unit, the nasal-lacrimal drainage system, and cranial nerves V (trigeminal) and VII (facial).
“We may think of all these components as an orchestra which is only as beautiful as the weakest instrument, and it is up to the clinician to detect, treat, rejuvenate and thereby ameliorate dissonance from the weakest instrument in that symphonic chain of ocular surface integrity,” Sheppard said.
This change in perspective is important because it asserts even more definitively that simply replacing tears artificially underserves the patient, he said.
The new definition also suggests that more attention to the neurosensory component should be rewarding, and a number of pharmaceutical targets are currently under investigation, as well as the newly approved neurostimulation therapy.
Allergan and Mimetogen have signed an agreement to develop and commercialize tavilermide (MIM-D3), a neuropeptide that enhances neural function and mucin secretion.
Another member of the neurotrophin family is NGF, recently approved in Europe and expected to be launched by Dompé by the end of next year for neurotrophic keratitis, in many ways the worst form of dry eye.
The last example is TrueTear, a novel neurostimulatory device by Allergan that directly emulates the natural trigeminal neurofeedback loop, essential to the production of healthy tears, Sheppard said.
Technology at hand
If ocular surface specialists are a minority in eye care, it is also true that the majority of clinicians are dealing with dry eye in some way. Eye care practitioners all need a better understanding of the underlying mechanisms and a better ability to decipher the sometimes hidden signs of dry eye to undertake a preventive approach and intervene at the earliest possible stage.
“This is a message that struggles to get through because many of these patients are relatively asymptomatic, just as patients with high cholesterol are asymptomatic until they have a heart attack,” Sheppard said.
Osmolarity is a key factor in the diagnosis of dry eye. TearLab provides a straightforward point-of-service diagnostic test that allows precise readings of the osmolarity in each eye within minutes and should be available equipment in every practice.
“Osmolarity is the foundation for my diagnosis. It provides noninvasive, painless, qualitative and quantitative assessment of dry eye severity, and in some patients, when osmolarity is very low, it directs toward other conditions,” Sheppard said.
Other office-based tests allow assessment of inflammation. InflammaDry (RPS/Quidel) is a small and easy-to-use device that detects elevated levels of MMP-9, an inflammatory marker that is consistently elevated in the tears of patients with dry eye.
“This guides my choice of therapy. The second-generation TearLab Discovery technology also has a noninvasive test for MMP-9 as well as for IL-1RA, a second marker for inflammation,” Sheppard said.
“A significant minority of clinicians have the TearLab in their office now, mainly ocular surface specialists. By the majority, the osmolarity test is still underutilized and yet it is so capable of focusing our treatment intelligently and cost-effectively rather than deploying empirical therapeutic choices,” he said.
Surgery requires controlled surface
Sheppard emphasized the importance of examining the ocular surface in patients who are asymptomatic, particularly when they are about to undergo surgery.
“They must have an exquisitely controlled ocular surface to obtain the best possible preoperative biometric results. I do far more preparation of the ocular surface prior to surgery than most clinicians do, probably because I am so used to dealing with dry eye patients. Still today, far too many surgeons ignore it completely,” he said.
His protocol for cataract and refractive surgery patients consists of a comprehensive history, which includes medications, diet, contact lens use, a detailed analysis on their quality of life, work environment and free-time environment, and an accurate analysis of symptoms or lack of symptoms. Patients then undergo a complete array of tests that includes multiple topographies, osmolarity testing, MMP-9, dynamic meibomian imaging, and many times allergy testing as well as a thorough examination including slit lamp and vital dye staining with fluorescein and lissamine.
“If patients have unreliable biometry or significant inflammation anywhere in the ocular surface or significant staining, they are not ready for surgery, especially if they are going to have a premium IOL. In these cases, I make sure they get anti-inflammatory therapy, appropriate nutrition and lubrication, I aggressively address lid disease with lid scrubs, and I often recommend punctal plugs, the amniotic membrane contact lens (ProKera, Bio-Tissue), neurostimulation (TrueTear) and, most commonly, LipiFlow thermal pulsation therapy (TearScience). I then make all the necessary medication and environmental changes to prepare the ocular surface for better surgical outcomes and better healing,” Sheppard said. – by Michela Cimberle
- For more information:
- John D. Sheppard, MD, MMSc, can be reached at Virginia Eye Consultants, 241 Corporate Blvd., Norfolk, VA 23502; email: docshep@hotmail.com.
Disclosure: Sheppard reports he is a consultant to Allergan, Bausch + Lomb, Bio-Tissue, TearScience, TearLab and RPS/Quidel.