From the Guidelines
Abnormal tear breakup time (TBUT) and keratoconjunctivitis sicca (KCS) are often caused by alterations in the tear film composition, particularly a deficiency in lipids, aqueous, or mucins 1.
Causes of Abnormal TBUT and KCS
- Aqueous tear deficiency: a condition where the eyes do not produce enough tears, leading to dryness and irritation 1
- Meibomian gland disease (MGD): a condition where the meibomian glands in the eyelids become clogged, reducing the production of lipids in the tear film 1
- Environmental factors: low humidity, prolonged digital screen use, and other environmental factors can exacerbate dry eye symptoms
- Underlying conditions: meibomian gland dysfunction, blepharitis, and Sjögren's syndrome can further disrupt the tear film and lead to chronic dry eye The tear break-up time test is used to evaluate the stability of the precorneal tear film, and break-up times less than 10 seconds are considered abnormal 1. Recurrent tear break-up in the same area may indicate localized anterior basement-membrane abnormalities 1.
From the Research
Causes of Abnormal Tear Breakup Time (TBUT) and Keratoconjunctivitis Sicca (KCS)
- Abnormal tear breakup time (TBUT) and keratoconjunctivitis sicca (KCS) are associated with dry eye disease (DED), a multifactorial disease characterized by reduced tear film stability and hyperosmolarity at the ocular surface 2.
- The pathogenesis of DED involves multiple ocular surface structures, including the cornea, conjunctiva, lacrimal glands, and meibomian glands, and is driven by chronic inflammation 2.
- Tear film abnormalities, including increased tear break-up time, osmolarity changes, and reduction in tear film volume, are indicators of DED and are perpetuated by underlying inflammatory signaling and secretion of inflammatory factors 2.
- Dry eye syndrome (DES) refers to a spectrum of ocular surface diseases with diverse and frequently multiple aetiologies, and is characterized by an abnormal tear film, including tear deficiency and anomalous tear composition 3.
Factors Contributing to Abnormal TBUT and KCS
- Inflammation and immune cell recruitment play a crucial role in the development of DED, and tear-soluble factors such as cytokines and chemokines can drive the altered profile of ocular surface cells contributing to the disease 2.
- The tear film secretion and its composition are regulated by the ocular surface in orchestration with the environment and bodily cues, and any dysregulation in ocular surface homeostasis can cause an increase in tear break-up time and reduction in tear film volume 2.
- Evaporative dry eye with short tear film breakup time can be effectively treated with combined tear film therapy targeted to aqueous, mucin, and lipid layers 4.
Diagnosis and Treatment of Abnormal TBUT and KCS
- Tear-film-oriented diagnosis and treatment (TFOD and TFOT) have emerged as a new concept for dry eye, focusing on the tear film dynamics and breakup patterns to diagnose dry-eye subtypes and propose optimal topical therapy 5.
- The use of biomarker testing in clinical settings can aid in the advancement of personalized medicine and represents the next step in managing DED 2.
- Combined tear film therapy, including hyaluronic acid, diquafosol tetrasodium, and carbomer-based lipid-containing eyedrops, can improve subjective symptoms and tear film quality in patients with refractory evaporative dry eye with short TBUT 4.