Technologies allow us to measure tear osmolarity or identify above normal ranges of matrix metalloproteinase-9 levels. Other diagnostic tools, such as meibomian gland imaging and lipid layer analysis, have transformed the way we assess appropriate tear production. We have remarkable tools to identify and help us monitor ocular surface conditions that may affect comfortable lens wear. In light of all this, do we still need our vital dyes, specifically fluorescein?
What Does Fluorescein Do?
Fluorescein’s unique properties provide an opportunity to view findings that are difficult to see without it. Slit lamps are commonly equipped with a cobalt blue light that optimizes viewing of fluorescein applied to the ocular surface. A Wratten filter will enhance the view even more.
Fluorescein is a hydrophilic molecule, which allows it to diffuse into the tear film. This gives us the opportunity to assess tear film breakup time (≥10 seconds is the normal range) and also the pattern of breakup (Figure 1). It also allows the assessment of corneal and conjunctival compromise through staining of the tissues (Figure 2). Negative staining, seen in conditions such as epithelial basement membrane dystrophy, is also easily visualized.
The line of Marx also stains with fluorescein, and any areas that are migrating anteriorly or are irregular in its pattern can easily be seen. Additionally, when everted, the lid wiper area on the superior lid can be assessed for the absorption of fluorescein. This is known as lid wiper epitheliopathy. Papillary responses on the superior tarsal plate can be visualized, as fluorescein diffuses into the regions of the tarsal plate that are not elevated and essentially highlights the margins of the papillae.
Unfortunately, many clinical findings are often difficult to view without appropriate application of fluorescein (Figure 3). For this reason, we utilize fluorescein on every patient at every encounter to help in our ocular surface evaluations.
With the minimal investment in cost and time that the use of fluorescein provides to our exams and the amount of valuable information that is obtained, we think this is a remarkable tool that supplements the higher diagnostic technologies in our evaluations. If trashing fluorescein is the new norm, we don’t want to be normal. CLS