Tear film lipid layer spread is proving to be an important clinical indicator of dry eye severity, as evidenced by two studies being presented this morning at ARVO 2019 in Vancouver.

A Tool for Disease Severity

In the first study, Japanese researchers enrolled 149 patients (149 eyes), including healthy eyes and those with dry eye (20 male, 129 female; mean age 61.9 years).¹ They recorded interference images of the tear film lipid layer with a tear interferometer. They then evaluated the lipid layer and calculated the average value of maximum and minimum distances from the lowest margin of the lipid layer spread following the cessation of the upward spread after the eye opened. The study looked at the tear meniscus radius, noninvasive tear film break-up time (NTBUT), fluorescein break-up time, corneal-epithelial damage scores (with a 15-point maximum), conjunctival epithelial damage scores (with a six-point maximum) and the Schirmer 1 test. Investigators then correlated the findings with tear film lipid layer spread distance.

The study found tear film lipid layer spread distance was significantly and positively correlated with the tear meniscus radius, Schirmer 1 test, NTBUT and fluorescein noninvasive breakup time. Researchers also reported tear film lipid layer spread distance was negatively correlated with corneal-epithelial damage and conjunctival-epithelial damage.

The findings of this study showed tear film lipid layer spread distance was significantly correlated with the quantitative and qualitative parameters for tear film and the ocular surface epithelium, researchers noted. Additionally, they suggested tear film lipid layer spread distance could be a clinically useful and simple method for evaluating the severity of dry eye.

“Evaluating the tear film lipid layer spread distance is a likely a good surrogate for grading severity, as it is significantly correlated with the quantitative and qualitative parameters for tear film and the ocular surface epithelium,” says Joseph Shovlin, OD, of Northeastern Eye Institute in Scranton, PA. “In clinical practice we are always looking for new metrics to evaluate in DED. Tear film lipid layer spread distance measures seem to be a simple and useful way of evaluating DED severity.” 

Revealing the Worst

The second study investigated whether tear film lipid layer spread could be an indicator for determining the severest form of aqueous tear deficient dry eye.

This investigation included 61 eyes of 61 subjects with no meibomian gland dysfunction and who presented with incomplete upward tear film lipid layer spread after the eye was opened. The researchers also used a tear interferometer to record the images. The eyes were subclassified into two groups based on the amount of observable lipid layer within a 6.8mm x 8.8mm area of the cornea: group A included incomplete, yet observable upward tear film lipid layer spread (23 eyes), and group B had 39 eyes with no observable incomplete upward tear film lipid layer spread.

Researchers assessed dry eye-related symptoms in the two groups by using the Visual Analog Scale, the Dry Eye Related Quality of Life Score, tear meniscus radius, NTBUT, fluorescein break-up time, corneal epithelial damage scores (15-points maximum), ocular surface epithelial damage scores (nine-point maximum) and the Schirmer 1 test.

Compared with group B, group A showed significantly greater symptoms including dryness, difficulty in opening the eye, lower NTBUT and fluorescein break-up time values and higher corneal epithelial damage and ocular surface epithelial damage scores.

Researchers noted there were no significant differences between the groups in tear volume parameters measured by the tear meniscus radius and the Schirmer 1 test. Additionally, 29% of group B eyes were treated with eye drops alone (no punctal plugs), yet 95.7% of the group A eyes required punctual plugs for proper treatment.

Noninvasive assessment of the upward tear film lipid layer spread can be a possible indicator for evaluating the severest form of aqueous tear deficient dry eye, the investigators said.²

“Patients with an incomplete upward spread may be better candidates for punctal occlusion due to the severity of their aqueous-deficient DED once inflammation has been controlled,” Dr. Shovlin adds.