Corneal Topography Device Can Also Measure Lid Margin Thickness

Clinicians have long relied on expertise to estimate changes in lid margin thickness (LMT) when examining patients for meibomian gland dysfunction (MGD). But some have found that utilizing a corneal topographer in a unique way can provide reliable quantitative results for lower lid margin thickness (LLMT). Now, a study in Eye & Contact Lens confirms this technique.

The prospective, single-center investigation recruited 90 consecutive healthy participants from 18 years to 79 years old. The patients were evaluated using the Keratograph^® 4 (OCULUS). The device is typically used for corneal topography, although it can measure tear meniscus height (TMH), and therefore the width of the lower lid margin may be gauged, according to the report.

Investigators considered data from the right eyes of participants, measured from the central lower lid, posterior eyelash line to the anterior border of the tear meniscus. Two readings were taken and averaged. To determine reliability, 2 trained operators imaged a set of 30 participants. In this intraoperator reproducibility step, operator 2 was masked to data collected by operator 1. They assessed mean LLMT at 0.94 mm, and 0.96 mm (P =.18), demonstrating reproducibility.

Of 90 total participants, men displayed thicker LLMT than women, but not significantly different (P =.32). Conversely, the study found mean lid margin thickness strongly correlated with age (P <.001). LLMT was 0.75 mm in participants from 18 to 29 years old, 0.87 mm in those from 30 to 39 years old, 0.99 mm in participants 40 to 49 years old, 1.02 mm for individuals 50 to 59 years old, 1.0 mm in individuals 60 to 69 years old, and 1.16 mm in participants from 70 to 79 years old. Mean lower TMH was “weakly negatively correlated with age,” (P =.047).

The study suggests measurement of LMT that indirectly shows eyelid pressure may be of great help to clinicians. Prior studies demonstrated meibum expression may potentially lower eyelid pressure. “Therefore, investigating the LMT and exploring the relationship between the LMT and the eyelid pressure can provide a new insight for some ocular disorders,” the research explains.

The device is not specifically designed to determine LLMT, and can only measure the lower lid margin, not upper, therefore representing a limitation of this study. Also, the research did not include participants with ocular disease.

Previous studies have shown that LLMT readings taken with the instrument were “slightly higher” than those with anterior segment optical coherence tomography, but lower than measurements with vernier micrometer. 

Reference

Yao J, Liu X, Zhu Y, Wang D. Measurement of the lower lid margin thickness by oculus keratograph. Eye & Contact Lens. Published online March 30, 2021. doi:10.1097/ICL.0000000000000782