Feature, Soapbox

Addressing blink inefficiency

Although blink efficiency is an essential part of the lacrimal functional unit, it has too frequently not received enough attention from clinicians who are focused on remediating other tear dysfunctions. [1]

However, researchers have been increasingly interested in blink performance with multiple studies showing how anomalies, such as an abnormally high ratio of incomplete blinks, can detract significantly from blink efficiency and efforts to reduce dry eye or dry contact lens symptoms.

Incomplete blinks increase ocular surface exposure and impair meibomian gland secretion. Because complaints of discomfort and dryness are very common, blink efficiency exercises have great potential for helping many patients. However, to achieve good outcomes, the action of giving patients a handout with detailed instructions for improving blink efficiency, most definitely needs to be supported by an explanation of the importance of efficient blinking in the maintenance of tear functions by the practitioner involved.

Guidance as to how exercises can be performed appropriately is also required. Consulting room time can be saved if support staff are trained to competently demonstrate an efficient blink practice session so that patients can go home having learnt how to perform blink efficiency exercises as specified in their handout (complete, soft, brief and natural looking).

Having multiple descriptors for these specifications helps. For example, if a patient’s initial efforts are not soft enough (too much hard squeeze force involved) then describing the desired soft complete blink as light, relaxed and gentle can improve their understanding of what is required. It can help to add the comment that while their initial squeeze blink effort for ‘completeness’ was good for completeness, such hard squeeze blinks take too long as well as looking unnatural when compared to complete, soft, brief and natural looking blinks.

In addition, it can be worth noting that hard squeeze blinks can attract the wrong kind of attention from work colleagues or family members who observe a blink practice session.

Tim Ho recently had a patient who asked for a letter which explained why he was practising squeeze blink closures. The patient’s lawyer is defending the patient against a sexual harassment claim made by one of the patient’s co-workers.

Nevertheless, there are many adherents to prescribing blink exercises which involve frequent sessions of voluntary prolonged ‘squeeze’ or ‘forced’ blinks and this approach has been supported by a very recent study (Kim et al. Therapeutic benefits etc. Cont Lens Ant Eye 2020). However, squeeze blink exercises involve intraocular pressure elevations of as much as 90mmHg (Coleman and Trokel. Direct-recorded IOP etc. Arch Ophthalmol 1969) and so are adverse for patients with or at risk for developing a baropathic disease such as glaucoma, axial and degenerative myopia, as well as keratoconus and other ectatic diseases.

Squeezed blinks have been shown to increase lipid secretion in unselected subjects but for patients with obstructed meibomian glands that outcome is less likely. Squeeze blinks may actually have an adverse overall effect with initial increased lipid flow from some unobstructed glands being the limit of benefit. The lipid reservoir in glands can be too easily depleted because gland recovery to normal lipid reservoir levels for optimally functioning glands which have been emptied has been found to take over two hours. Consequently, ‘squeezed’ lipid flow appears likely to be followed by a relapse to an absence or major reduction of flow during a very extended gland recovery period.

Practising blinks which are complete, brief, soft and natural looking has the potential to be immediately therapeutic because complete blinks increase tear layer thickness, help to distribute mucin over a desiccated epithelium, and improve lipid flow according to the normal capacity for complete blinks to promote secretion. In addition, they promote the establishment of a motor memory of efficient blinking which helps to compensate for low blink rates that occur during periods involving reading and screen-based activities. Unfortunately, squeeze blinking practice sessions have the potential to destroy that kind of motor memory.

Copies of the updated Blink Efficiency Exercises handout are available from: c.mcmonnies@unsw.edu.au.

1. McMonnies CW. Diagnosis and remediation of blink inefficiency. Cont Lens Ant Eye; Published ahead of print May 2020.

ABOUT THE AUTHOR

Name: Charles McMonnies
Qualifications: DSC
Workplace: School of Optometry and Vision Science, University of New South Wales
Position: Honorary Professor
Location: Sydney
Years In The Profession: 58