The Schirmer Tear Test

The Schirmer's Tear Test was originally developed for estimation of tear function in humans. The three methods included use of blotting paper, cut into strips of 35x5mm. The test involves folding the end of the blotting paper and hooking it over the margin of the inferior palpebra and waiting five minutes (Cho and Yap 1993).

· STT1: simply hooking the strip of blotting pater over the inf. palpebral margin and measuring the wetting after five minutes.

· STT2: as STT1, but first anaesthetize the eye and irritate the nasal mucosa with a hair brush.

· STT3: as STT2, but instead of irritating nasal mucosa, the patient is asked to look at the sun. Only the STT1 has been widely used in human ophthalmology and is referred to as "Schirmer Test"(Cho and Yap 1993).

In veterinary ophthalmology the STT1 has become a standard procedure in the diagnosis of quantitative dry eye disease; hereafter STT will be synonymous with STT1. STT was introduced by Rubin et al (1965) for use in the canine. The strip(made of Whatman 41 filter paper) is placed in the inferior conjunctival fornix and removed after one minute and measured(Wyman et al 1995). In estimation of normal STT values, Gelatt et al(1975) found 21,0mm wetting/min (sd:4,2mm) on 97 dogs free of ocular disease. In a resent study(Wyman et al 1995) 100 normal dogs had STTs of 22,6mm/min(sd: 3,8mm). Hirsh and Kaswan (1995) found STTs on normal dogs to be 19,0mm(sd: 5,3mm). A recent study evaluating STT-strips with a colour indicator showed a slight difference of the Colour impregnated STT-strips compared to standard STT-strips (Wyman et al 1995), with colour impregnated strips giving slightly lower readings. Hirsh and Kaswan(1995) tested the same colour impregnated STT-strips and found no statistical difference.

Håkanson and Arnesson(1997) described a temporal variation in tear production in a group of healthy Beagles, indicating that STTs on consecutive days may vary considerably, but mostly within 0-4mm/min. Berger and King (1998) showed that fluctuations in the STT values in dogs occur on both a daily and weekly basis. Romano et al (1994) found a circadian rhythm of lacrimal secretion in humans, peaking at 6pm and lowest at 6am. During sleep the period of photic as well as irritative stimulation is minimal thus resulting in a lower reflex tearing. The diagnosis of quantitative dry eye disease is usually suggested if the STT is 0-9mm/min, with symptomatic cases wetting less than 5mm/min (Kaswan et al 1995).

This page was authored by T. F. Evans October 2000.