Observing the initial changes of the cornea and conjunctiva is a critical component in the evaluation and diagnosis of Dry Eye Disease. Vital dye staining of the ocular surface as a diagnostic tool was first suggested as far back as 1924.¹ Several dyes have been used in the staining of the cornea or conjunctiva for evaluation of ocular surface changes in patients with DES, these include fluorescein, rose bengal, and lissamine green.

Vital dye staining has been reported as a useful tool for the diagnosis and assessment of various ocular surface disorders.^2-5 Because it is less toxic, easily visible, and highly tolerable to the patients, fluorescein has been the most commonly used dye for the evaluation of ocular surface disorders.² Fluorescein is used more frequently for identifying corneal epithelial lesions rather than conjunctival lesions.⁶ In contrast, rose bengal generally stains the conjunctiva more than the cornea. Rose bengal stains dead or degenerated epithelial cells, as well as healthy epithelial cells without a healthy protein layer (mainly mucin).⁷ However, rose bengal may induce intrinsic toxicity and symptoms of irritation after instillation.^3,8 Lissamine green has a staining pattern that is very similar to that of rose bengal.⁹ Compared with rose bengal, it has some advantages, such as less toxicity and greater tolerability to patients.³

Reports on ocular surface vital staining continue, yet studies with a dye mixture of fluorescein and lissamine green have been rarely performed.^10,11 Korb proposed that a mixture of 2% fluorescein and 1% lissamine green was the preferred dye for simultaneous corneal and conjunctival staining without an adverse sensation and that it could be a useful substitute for individual dyes.¹⁰ In a recent study of fifty patients with dry eye disease, a mixed solution of 1% fluorescein and 1% lissamine green offered excellent simultaneous staining of the cornea and conjunctiva, maintaining the unique staining characteristics of each dye.¹²

There is a combination 0.5% lissamine green/1.0% sodium fluorescein product commercially available. Fluramene is distributed by EyeSupply USA* and is available in a 15 mL solution. I use this solution in my practice every day and have found that corneal, conjunctival and lid margin changes are easily noted with the drop. I like the convenience of the drop, instead of having to moisten multiple strips. In my opinion, the brilliance of lissamine in solution is superior to the stain obtained with a lissamine strip. (This is my personal opinion only; I have no data to back it up.) If there is a drawback to the solution it is that it stains the eyelids heavily which can take some time to remove. I learned a trick from a corneal specialist I once worked with that might help: apply a drop of the solution to the wooden end of a cotton swab and then gingerly apply a small amount of the solution to the temporal conjunctiva, allowing capillary action to draw the solution onto the conjunctiva. This minimizes the amount of dye onto the patient's eyelids.

Use of double vital staining with fluorescein and lissamine green is an easy and convenient method for the evaluation of the corneal and conjunctival epithelia simultaneously with minimal irritation or intrinsic toxicity compared with their conventional methods of staining. The Yoon study found double vital staining using a mixed dye of 1% fluorescein and 1% lissamine green correlated with symptoms and some ocular surface parameters and helped to identify ocular surface changes easily. The authors conclude "It may be a useful method for the diagnosis of dry eye and the assessment of the therapeutic effect in patients" with dry eye disease.¹²

We are now including an email link, "Contact Dr. Bowling" in the masthead of the newsletter, so I can hear from you. If you have any comments, thoughts or suggestions, please feel free to share them with me!

* Disclosure: EyeSupply USA is the sponsor of this newsletter.

REFERENCES
1. Marx E. Über vitale Färbungen am Auge und an den Lidern. I. Über Anatomie Physiologie und Pathologie des Augenlidrander und der Tränenpunkte. Graefes Arch Ophthalmol 1924; 114: 465–482.
2. Kim J. The use of vital dyes in corneal disease. Curr Opin Ophthalmol 2000; 11:241–247.
3. Manning FJ, Wehrly SR, Foulks GN. Patient tolerance and ocular surface staining characteristics of lissamine green versus rose bengal. Ophthalmology 1995; 102: 1953–1957.
4. Kim J, Foulks GN. Evaluation of the effect of lissamine green and rose bengal on human corneal epithelial cells. Cornea 1999; 18: 328–332.
5. Lee SH, Tseng SC. Rose bengal staining and cytologic characteristics associated with lipid tear deficiency. Am J Ophthalmol 1997; 124: 736–750.
6. Bron AJ. The Doyne Lecture: reflections on the tears. Eye (Lond) 1997; 11: 583–602.
7. Feenstra RP, Tseng SC. What's actually stained by rose bengal? Arch Ophthalmol 1992; 110: 984–993.
8. Feenstra RP, Tseng SC. Comparison of fluorescein and rose Bengal staining. Ophthalmology 1995; 102: 1953–1957.
9. Norn MS. Lissamine green. Vital staining of cornea and conjunctiva. Acta Ophthalmol 1973; 51: 483–491.
10. Korb DR, Herman JP, Finnemore VM, et al. An evaluation of the efficacy of fluorescein rose bengal, lissamine green, and a new dye mixture for ocular surface staining. Eye Contact Lens 2008; 34: 61–64.
11. Toda I, Tsubota K. Practical double vital staining for ocular surface evaluation. Cornea 1993; 12: 366–367.
12. Yoon KC, Im SK, Kim HG, et al. Usefulness of double vital staining with 1% fluorescein and 1% lissamine green in patients with dry eye syndrome. Cornea 2011; 30: 972–976.