Optimizing evaluation of Lissamine Green parameters for ocular surface staining

The recently published seminal dry eye workshop proceedings defined Lissamine Green (LG), an organic dye, as a gold standard for demonstrating ocular surface staining. The purpose of the current study was to determine the optimal parameters of 1% LG instillation for the ocular surface examination in dry eye patients.

Prospective and observational quality improvement study.

A quality improvement study evaluated 16 eyes from eight dry eye patients with different levels of severity. LG (1%), in three volumes (5, 10, and 20 μl) was instilled into the conjunctival cul-de-sac, and four masked observers with different levels of clinical expertise examined the patients with and without red filter. The staining pattern of the conjunctiva and cornea was documented with the Oxford scale within 4 min of LG instillation. Optimal volume and inter-observer reliability were assessed.

All dye volumes were tolerated well by all patients. Experienced observers preferred 10 μl volume because of the ease of examination and accuracy. Although instillation of 20 μl yielded similar scores as 10 μl, it resulted in overflow of the lid and facial skin staining. The use of red filter significantly improved reading scores (P<0.01). Inter-observer reliability was higher for conjunctival scores than for corneal scores for all patients. The highest reliability was demonstrated with 10 μl volume and increased with greater experience of the observer.

Ocular surface examination with instillation of 10 μl 1% LG has good inter-observer reliability and is well tolerated. Observation through a red filter facilitates the examination.