Tear production levels and dry eye disease
Reviewed by Kurt Spiteri Cornish

Dry eye disease (DED) is multifactorial, caused by an alteration in the quality or quantity of tear film’s three layers. Several tests are available for diagnosis. The aim of this study was to determine if the Schirmer test (ST) could be used as a predictor of dry eye severity. A total of 1090 patients with DED were grouped according to pre-determined cut-off levels on ST1 (without anaesthesia), i.e. 5mm, 10mm and 15mm. Analysis revealed that patients with lower tear production as measured on ST1 presented with more severe DED (as defined by tear osmolarity, tear meniscus height, break-up time and ocular surface staining) compared to higher tear production. However, there was no correlation with meibum expressibility (ME) or quality (MQ) or the diagnosis or meibomian gland dysfunction (MGD). The authors conclude that the ST is a robust discriminator for dry eye severity level. However, the ST cannot significantly discriminate parameters related to meibomian gland function. This is because this cohort of patients tend to have unstable tear lipid layer with subsequent increased tear evaporation and DED, but normal tear production (hence normal ST1 values)

Tear production levels and dry eye disease severity in a large Norwegian cohort.
Yazdani M, Chen X, Tashbayev B, et al.
CURRENT EYE RESEARCH
2018;43(12):1465-70