the tear film stability is closely related to the tear volume - thus, the tear volume is an important parameter to conduct tear-film-oriented-therapy properly, where the treatment of dry eye disease or the postoperative care for refractive and cataract surgeries are typical examples of such.
The “Strip Meniscometry Tube (SMTube)” is a medical device for a simple, accurate, swift and minimally-invasive assessment of tear volume - “Strip Meniscometry” is a term of a methodology for the tear volume evaluation, of which the original paper was published in 2006 (Dogru 2006). Then in 2011, it has been reported that the strip meniscometry testing was useful in the diagnosis of dry eye disease, showing a statistically significant correlation with other ocular surface examinations such as the Schirmer test, tear film breakup time measurement, and vital staining scores (Ibrahim 2011) –
All you do is to immerse the tip of the SMTube strip into the tear meniscus of the lower eyelid for 5 seconds. And column will be stained with blue dye as the SMTube absorbs tears. The length of stained column quantifies the tear meniscus volume - since SMTube is used right on ocular surfaces, the safety is highly considered, the material and structure were carefully chosen and designed so that no damage ought to occur on the ocular surface in case the tip of the strip touches cornea or conjunctiva.
A number of reports have been published in terms of the use of SMTube in their clinical studies - here are some of the examples :