Is Schirmer’s test of any value in evaluating dry eye?

Low correlation with symptoms

William B. Trattler

Schirmer’s test may have a role in the research setting in assessing the effect of treatment on the average score of a patient population. However, on a clinical basis, the results of Schirmer’s test are generally not consistent with clinical findings, and so it may not be as useful as other modalities in assessing the level of dryness.

For instance, it is not uncommon to see a patient with a very low Schirmer score who does not have signs or symptoms of dryness on examination, and the reverse is true as well — I might see someone who is wet on the Schirmer’s strip, but they definitely have dry eye.

Obviously, a score closer to zero on the test indicates a higher likelihood of the presence of dry eye, but even a score of zero may not be clinically relevant or, because of the low specificity, an indication of absolute dryness. Even a score of zero does not help differentiate between a mild, moderate or severe disease course. Instilling fluorescein in the eye to assess tear film breakup time and corneal staining are far more predictive of dry eye, as well as useful in differentiating the severity of the dryness.

Knowing the severity of the disease will, in turn, drive our treatment decision. If it is mild, we may start with just artificial tears, and if it is moderate to severe, we may opt for topical cyclosporine, topical steroids and/or punctal plugs. Quantifying the level of dryness is crucial, but it is in the context of a surgical candidate where this becomes most important: Schirmer’s test in general may not be the most effective method for screening seemingly asymptomatic patients undergoing either cataract or refractive surgery.

William B. Trattler, MD, is an OSN SuperSite Board Member and in private practice at the Center for Excellence in Eye Care in Miami.

Valuable in context

The clinical value of the Schirmer’s test has long been controversial, but when performed correctly and interpreted in the context of other diagnostics, the Schirmer’s test can be of value.

Mark B. Abelson

Innate inter- and intra-patient variability (normal human tear volume may range from 7 µL to 30 µL, while tear turnover rates range from 0.5 µL/minute to 2.2 µL/minute) suggests the importance of interpreting Schirmer’s results in terms of extremes rather than in relation to a distinct threshold. A lower reading (less than 5 mm/5 minutes) may mean a high likelihood of dry eye and a high reading (more than 10 mm/5 minutes) is more often indicative of a normal ocular state; readings in-between these two values may be inconclusive.

The phenomenon of reflex tearing can complicate results but may also tell you something about the patient’s ocular manifestations. Testing in Ora’s Controlled Adverse Environment, for example, has demonstrated that reflex tearing occurs sooner in healthy patients than in those with increased dry eye severity.

Finally, it is important to consider the Schirmer’s test in conjunction with other diagnostic results (eg, lissamine green staining, keratitis, symptomatic breakup time, tear film breakup time, symptomatology, systemic involvement, ocular protection index, computerized time-area assessment of tear film breakup). Alternative methods to evaluate clinical evidence of tear production and tear flow include the phenol thread test, fluorophotometry and tear meniscus height.

The results can also be strengthened by ensuring that Schirmer’s test is performed properly: Wipe away any moisture surrounding the eye prior to testing; place the folded strip on the junction of the lateral one-third and medial two-thirds of the lid; instruct the patient to close his or her eyes and to stay still for the duration of the test; and remove the test strip and try again if significant wetting occurs immediately after insertion.

Mark B. Abelson, MD, FRCSC, is an associate clinical professor at Harvard Medical School, senior clinical scientist at Schepens Eye Research Institute and chief scientific officer of Ora Inc.