Research Update

Research Update Issue 8

August 2017  

Welcome to our monthly research update
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
Special Issue – August 2017
The TFOS Dry Eye Workshop II


Since publication of the first TFOS DEWS report 10 years ago, the number of publications relating to dry eye has almost doubled. This reflects the enormous amount of work being done in this area and warranted an upgrading of the first report.

Two years of work by 12 subcommittees, made up of 150 experts from 23 countries, has been published by the Tear Film and Ocular Surface Society as the TFOS DEWS II Report. The report is published in The Ocular Surface and is also available via the TFOS website.

The objectives of the workshop were to:

  • Update the definition, classification and diagnosis of dry eye disease (DED)
  • Critically assess the etiology, mechanism, distribution and impact of this disorder
  • Address its management and therapy

Dry eye was identified as a disease for the first time during the TFOS DEWS I. The new definition of DED includes the phrase ‘loss of homeostatis’. The revised definition states:

  • 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.

Here are some excerpts from the report.

The IACLE Education Team
Journals reviewed in this issue  

  The Ocular Surface 15:3

Men vs women
While they play a major role in the regulation of the ocular surface and adnexal tissues, and in the difference in DED prevalence between men and women, further research is needed to clarify the precise nature, extent, and mechanisms of these sex, gender, and endocrine effects on the eye in health and disease. A deeper understanding of these issues may result in improved, more tailored and appropriate options for the treatment of DED.

Ocul Surf 2017;15:3 284-333. Click here for full text


Prevalence and risk factors
The prevalence of DED, with and without symptoms, ranges from 5% to 50%. Prevalence of DED based on signs only is even more variable, reaching up to 75% in some populations. Asian ethnicity appears to be a risk factor, but the reason for this is, as yet, unclear. Higher rates of DED in women compared to men only become significant with increasing age. The most severe economic impact of DED likely results from indirect costs related to decreased work productivity. Future needs include a detailed evaluation of the prevalence of DED of varying severity, prevalence in youth, incidence studies in various populations, and the impact of the use of current technologies, such as mobile devices.

Ocul Surf 2017;15:3 334-365. Click here for full text


Structure and measurement
Evidence continues to support the more contemporary two-phase model of the tear film, with a lipid layer overlying a muco-aqueous phase. While tear proteins are reported to change in DED, no definitive set of proteins or changes in protein levels have been validated to aid in diagnosis. There is a need to further characterize the biochemistry of the tear film and for ways to dynamically measure tear film osmolarity and markers of inflammation over the whole ocular surface.

Ocul Surf 2017;15:3 366-403. Click here for full text


Role of cold receptors
Cold thermoreceptors continuously discharge nerve impulses at the normal ocular surface temperature, responding to warming or cooling and to osmolarity increases, likely contributing to reflex control of basal tear production and blinking. Studies to date suggest potential merit in exploring treatment strategies involving cold receptors to manage DED symptoms.

Ocular Surface 2017;15:3 404-437. Click here for full text


Hyperosmolarity: hallmark of DED
Meibomian gland dysfunction (MGD) and Sjögren and non-Sjögren lacrimal disease remain leading causes of evaporative and aqueous-deficient DED, respectively. The core mechanism of DED is tear hyperosmolarity, which is the hallmark of the disease. It damages the ocular surface both directly and by initiating inflammation. The role of increased friction in DED and its subsequent sequelae deserves further investigation. Improved understanding of the role of subclinical inflammation in the early stages of DED also warrants further study.

Ocular Surface 2017;15:3 438-510. Click here for full text


Medications, CLs and other interventions
Topical and systemic medications, contact lenses, ophthalmic surgeries, and non-surgical procedures can cause DED. Future recommendations for research include conducting further epidemiological studies to better define risk factors, creating less toxic medications and preservatives, devising less invasive ophthalmic procedures, and developing strategies for the detection of early DED prior to surgical interventions.

Ocular Surface 2017;15:3 511-538. Click here for full text


Identifying DED
If DED is suspected, a positive result to a screening questionnaire such as the 5-item Dry Eye Questionnaire (DEQ-5) or the Ocular Surface Disease Index (OSDI) should trigger further evaluation, with tear break-up time (non-invasive methods preferred), tear film osmolarity determination, and ocular surface staining (that includes the cornea, conjunctiva and lid margin) with fluorescein and lissamine green. Identification of a disruption in tear film homeostasis with these tests allows a diagnosis of dry eye to be made. Other tests, such as meibography, lipid layer interferometry, evaporation and tear volume measurements can help clarify where the individual with DED falls on the evaporative and aqueous-deficient DED subtype classification spectrum.

Ocular Surface 2017;15:3 539-574. Click here for full text


Restoration of tear film homeostasis is the ultimate goal in the management of DED. Determining whether the major cause(s) of an individual’s DED pertains predominantly to aqueous tear deficiency or to evaporative causes, or both, is critical in helping select the most appropriate management strategy. Although staged management and treatment recommendations are presented, the heterogeneity of the DED patient population mandates that practitioners manage and treat patients based on individual profiles, characteristics and responses.

Ocular Surface 2017;15:3 575-628. Click here for full text

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