Dry eye research - a review

High prevalence of abnormal ocular surface tests in a healthy paediatric population

Rojas-Carabali et al, 2020

Clin Ophthalmol. 2020;14:3427-38


Review: Towards the end of 2020, this study reported that in a group of otherwise healthy seven to 17-year-olds, 33% could be diagnosed with dry eye disease (DED) according to the TFOS DEWSII classification. This study had some fairly startling findings including 36.6% exhibiting partial meibomian gland loss, positive lissamine green staining in 70.8%, positive fluorescein staining in 47.4% and an average tear meniscus height of 0.19mm. Daily screen time was 5.59± 2.77 hours and the most popular screen was the smartphone.


Comment: While there have been other studies on DED in children, particularly with device use, this is one of the first that has comprehensively looked at signs and symptoms in younger patients. Though environmental factors are suspected in the aetiology of paediatric dry eye, the authors of this study highlighted the importance of standardising normal paediatric ocular surface test values to help practitioners recognise and promptly treat ocular surface disease in this population. Another consideration with this study is if we’re seeing this degree of DED in young individuals, how will their eyes look in another five, 10 or 20 years? Is this the tip of the iceberg for DED prevalence?


Evaluation of the effect of blink type on tear-film breakup time and its estimation

Szczesna-Iskander and Quintana, 2020

Optom Vis Sci. 2020;97(11):954-61


Review: Tear breakup times (TBUTs) are recommended as part of the DEWSII battery of diagnostic tests and eye care practitioners commonly do this for all dry eye and contact lens wearing patients. But is the way we do the test accurate?


The purpose of this study was to determine to what extent the type of blink affects TBUT and its assessment using two types of videokeratoscopes and the fluorescein test. The authors looked at 33 patients and the effect of natural (short) blinks and forced (unnaturally prolonged) blinks on tear breakup times, measured with the Oculus Keratograph 5M, the Medmont E300 and the classic fluorescein test.


Forced blinking significantly shortened TBUT in all measuring modalities. The mean difference between breakup time after natural and forced blink was 3.2 (P = .002), 2.4 (P = .005), and 2.1 seconds (P = .002), for the Keratograph 5M, E300 and fluorescein test, respectively.


Comment: This study highlights the importance of doing clinical testing correctly, no matter which method you’re using. “Do a few good blinks and hold open for as long as you can,” may not be the best instructions for patients anymore. Between normal blinks and forced blinks a variation of TBUT between two or three seconds could be the difference between identifying reduced TBUT or normal TBUT. Asking the patient to blink normally a few times and repeating the test several times may give us more accurate results.


Effects of terpinen-4-ol on meibomian gland epithelial cells in vitro

Chen et al (2020)

Cornea 2020;39(12):1541-6


Review: Demodex mite infestation has been linked to chalazion development, meibomian gland dysfunction (MGD) and blepharitis. Tea tree oil-containing lid hygiene measures are commonly recommended and are an effective treatment. But Terpinen-4-ol (T4O), an active tea tree oil component, is also known to be toxic to non-ocular epithelial cells. The authors of this paper hypothesized that T4O toxicity could extend to human meibomian gland epithelial cells.


In vitro testing of immortalised human meibomian gland epithelial cells were cultured with varying concentrations (1.0-0.001%) of T4O under different conditions for up to five days. There was a dose- and time-dependent decrease in the cell survival. Overall, even at levels 10- to 100-fold lower than demodicidal concentrations, T4O from tea tree oil was toxic to human meibomian gland epithelial cells in vitro.


Comment: Lid hygiene plays a role in the management of MGD and anterior blepharitis of all subtypes, including Demodex blepharitis. While we have moved on from baby shampoo, particularly once the negative effects on goblet cells were known¹, recently more practitioners have chosen to use tea tree oil-containing formulations due to its demonstrated effectiveness as an antibacterial agent and Demodex treatment. So while more studies are needed, particularly in vivo and considering the 15-minute contact time in this study was longer than we would typically use in practice, this paper may cause us to be more mindful about what product we recommend, the strength of its active ingredients and at what frequency we use it. Tea tree-based products may not always be the best choice of treatment.


Severity of DED, work productivity and activity impairment in dry eye in the dry eye assessment & management (DREAM) study

Greco et al (2020)

Ophthalmology 2020


Review: Dry eye disease (DED) can impact our patients lives beyond the ocular affects alone and is associated with higher self-reported levels of anxiety and depression². Individuals with moderate to severe DED, enrolled in the multicentre DREAM study, completed a work productivity and activity impairment questionnaire at the beginning of this randomised clinical trial and again at six and 12 months to evaluate the association between DED severity and work productivity and activity impairment.


These results were assessed in parallel against DED symptoms and signs (conjunctival and corneal staining, TBUT and Schirmer test). Findings included higher Ocular Surface Disease Index (OSDI) symptom scores associated with greater absenteeism, presenteeism and activity impairment; and worse corneal staining and TBUT associated with higher overall work impairment and lower activity levels.


Comment: As eye care practitioners, we can have an impact not only on our patients’ vision and ocular health, but also on their quality of life. Through actively managing DED, we can positively affect our patients’ vision, mood and ability to work and take part in the activities they enjoy.



  1. Craig J, Sung J, Wang M, Cheung I, Sherwin T, Ismail S. Commercial lid cleanser outperforms baby shampoo for management of blepharitis in randomised, double-masked clinical trial. Invest Ophthalmol Vis Sci. 2017;58
  2. Kitazawa M, Sakamoto C, Yoshimura M, Kawashima M, Inoue S, Mimura M, et al. The Relationship of DED with depression and anxiety: a naturalistic observational study. Transl Vis Sci Technol. 2018;7(6):35


Adele Jefferies is an Auckland-based optometrist, national clinical manager for Matthews Eyewear Eyecare and a teaching fellow at the University of Auckland School of Optometry & Vision Science. She has a special interest in dry eye and ocular surface disease, contact lenses and therapeutics.


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