Dry Eye Dx and Tx
An Easier Way to View Lissamine Green Staining
By Milton M. Hom, OD, FAAO
In the dark ages of dry eye, we mostly relied on symptoms for diagnosis. Now, we have several tools at our disposal. Some tests require sophisticated instrumentation (such as tear osmolarity); others are simple, yet scientific, such as the 12-question Ocular Surface Disease Index (OSDI) questionnaire. For myself, one of my most favorite tools for diagnosis and treatment monitoring is lissamine green staining.
The Lissamine Green Puzzle
You could almost say that I have had a love-hate relationship with lissamine green. Time and time again, this dye has puzzled me. When I first started to use it, I felt it was worthless compared to time-honored fluorescein staining. The results were certainly not comparable—or so it seemed.
What I did not realize was that the dye was telling me a completely different story than what fluorescein was. Lissamine green stains damaged and dead cells, although there is controversy about this. Fluorescein may stain damaged cells. We did a study showing that lissamine green staining typically will stain one grade lower compared to fluorescein staining on the conjunctiva (Hom, ARVO 2008 #5298/D740). What puzzled me was when I started to see cases in which the lissamine green staining was greater than the fluorescein staining. This went against findings in previous studies I had done. At this point, I almost felt that lissamine green was an unreliable tool.
Based on Korb's (2008) work, I realized that cases in which lissamine green staining was greater than fluorescein staining occurred when there was much greater compromise on the ocular surface, i.e. more dead cells than damaged cells. We see more lissamine green staining in cases of greater severity levels of dry eye.
Enhanced Stain Viewing
With fluorescein stain, we can use a yellow filter to enhance our viewing. Recently, I have been using a red filter for viewing lissamine green staining. It is a Wratten 25 filter, mostly used for black and white photography. You can mount it as you would a yellow filter. I got mine on Ebay for about $25.
So what does the filter do? It makes lissamine green staining appear black. Figure 1 shows lissamine green staining under normal illumination. Figure 2 is the same eye viewed through a Wratten 25 filter. The staining appears to be more pronounced.
Figure 1. Lissamine green staining under white light.
Figure 2. Same eye viewed through a Wratten 25 filter. The lissamine green staining appears black.
Some of my colleagues remark that they love the soothing color of lissamine green. If you enjoy the color, you will not enjoy this filter. However, the filter has helped me view lissamine green staining, especially in cases in which I am not sure whether the stain is present or not. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #178.
Dr. Hom is the author of Manual of Contact Lens Prescribing and Fitting 3e and Mosby's Ocular Drug Consult. He practices in Azusa, Calif. Dr. Hom receives research grants from AMO, Allergan, B+L, and Inspire Pharmaceuticals.