Indian Journal of Ophthalmology

: 1984  |  Volume : 32  |  Issue : 5  |  Page : 454--455

Tear film breakup time (B.U.T.) in sub clinical dry eyes

OP Kulshrestha, Puspa Talwar, Madhu Mathur 
 S.M.S. Medical College, Jaipur, India

Correspondence Address:
O P Kulshrestha
S.M.S. Medical College, Jaipur

How to cite this article:
Kulshrestha O P, Talwar P, Mathur M. Tear film breakup time (B.U.T.) in sub clinical dry eyes.Indian J Ophthalmol 1984;32:454-455

How to cite this URL:
Kulshrestha O P, Talwar P, Mathur M. Tear film breakup time (B.U.T.) in sub clinical dry eyes. Indian J Ophthalmol [serial online] 1984 [cited 2022 Jul 4 ];32:454-455
Available from:

Full Text

In dry eye states changes occur in precor­neal tear film which is a complex liquid struc­ture covering the exposed corneal and conjunctival surfaces of the eye. It is a thin film basically unstable and should be renewed periodically in order to maintain a continous covering on the cornea.[1],[2],[3]

Deficiency of tear secretions lead to dry eyes. Severe dryness is easy to diagnose and difficult to manage. Subclinical dry eyes are the ones which involve frequent consultation with doctors. These are troublesome con­ditions associated with deficiency of tear sec­retions causing constant irritation of the eyes and perpetual discomfort to some of the patient.

Diagnosis of subclinical dry eyes is impor­tant though difficult unless secretions are tes­ted by schirmer's test and further confirmed by tear film breakup time (B.U.T.). Deficiency of lacrimal secretion mainly can be demonstrated by the former test but results of this test are not reliable for mucin deficiency states of conjunctiva. In normal eyes tear film breakup time is 15-45 seconds. Less than 10 seconds are diagnostic of dry eyes irrespective of lack of objective signs referrable to tear deficiency.


Twenty five patients (50 eyes) suspected of symptoms referrable to dry eyes, like burning, constant discomfort to the eyes, sensation of dryness and or mucinous discharge were selected for this study and compared with same group of normal individuals with healthy state of conjunctiva and cornea.

The test of tear film breakup time (B.U.T.) involves the use of normal physiological phenomenon of dry spot formation. The interval between the last complete blink and development of first randomly distributed dry spot in the precorneal tear film is defined as breakup time. Cobalt blue filter of the slit lamp is used to see the surface of the cornea after staining with fluorescein strips.

While doingn this test (B.U.T.) topical anaesthetic should not be used as irritation casued by these drops may produce supurious results. The patient should be asked not to blink as it will make the results fallacious.


Absolute or marked reduction in secretion of tears produce Keratoconjunctivitis sicca which include many conditions like Sjogren's syndrome, following stevens Johnson's syn­drome, erythema multiforme, systemic lupus erythematosis, scleroderma and wagners granulomatosis.

What is also commonly seen in India but scantily reported in western literature is mucin deficiency states in which mucin pro­ducing goblet cells of the conjunctiva are primarily affected. A typical condition is deficiency of vitamin A (Xerosis or Xerophthalmia). Such deficiency leads to areas non-wettability on corneal surface. Since mucin is the agent that effects wetting of corneal surface, a decrease in mucin produc­tion adversely effects tear film stability. A con­tinuous tear film can form only with difficulty across corneal and conjunctival surface that lacks a good mucin layer.

Other conditions causing recurrent con­junctival inflammation destroy the normal conjunctival structure (loss of goblet cells) and produce similar mucin deficiency states. These include pemphigoid, stevens Johnson's syndrome, extensive trachoma and chemical burns.

Tear film breakup time is an extremely use­ful test in such mucin deficiency states and more informative than Schirmer's test alone. The key to B.U.T. test is to recognise randomly distributed dry spots. But B.U.T. will not be significantly informative if there is epithelial abnormality on corneal surface.

We found absolute reduction in breakup time in 14 eyes (0-5 seconds) and in another six eyes it was significantly reduced (5-10 seconds) while in seven eyes it was relatively reduced (11-15 seconds). The readings on Schirmer test in some of the former cases did not show proportionate reduction.


Study of tear film berakup time in 50 sub­clinical dry eyes was done. B.U.T. was less than 5 seconds in fourteen eyes, 5-10 seconds in six eyes and 11-15 seconds in seven eyes while Schirmer's test in most of them was less informative.


1Alper, M.G. 1975. Tran. Am. Ophthalmol. Soc. 73:323.
2Baun, J.L. 1973. Int. Ophthalmol. Clin. 13: 157.
3Beitch, I. 1970. Incest Ophthalmol. 9: 827.