Two of the basic tenets of surgery are exposure and visualization. In ophthalmic surgery we often take these two principles for granted because the eye is readily accessible and we can usually see the pathology directly. This is especially true when we are performing corneal, cataract, and retinal procedures. However, any clouding of the ocular media can interfere with the quality of our view during intraocular manipulations. Ophthalmic surgical dyes have become valuable tools and are now widely used for both anterior and posterior segment indications.
Cataract surgery: The continuous curvilinear capsulorhexis is the most difficult as well as the most critical step in modern cataract surgery. A properly constructed capsulorhexis maintains the IOL implant in the proper position and resists radial tears of the capsular bag. An adequate red reflex is necessary for the surgeon to see the leading edge of the capsular tear with retroillumination as the capsulorhexis is created. The capsulorhexis edge may be difficult or unable to be seen if the red reflex is poor or absent. In the case of a mature cataract, not only is there no red reflex but also milky liquid cortex can escape into the anterior chamber further clouding an already poor view of the anterior lens capsule. Oblique illumination with a light pipe angled from the side is helpful but still suboptimal. Therefore, prior to capsular dyes, we would struggle to complete a capsulorhexis in such instances and would sometimes have to convert to a can-opener style capsulotomy.
Capsular dyes have dramatically improved our ability to perform the capsulorhexis in these circumstances. In fact, they have eliminated the problem of visualizing the capsule. Indocyanine green (ICG) has been used but requires preparation (reconstitution and dilution); it also should be filtered to prevent undissolved particles from entering the eye. Trypan blue 0.06% ophthalmic solution is FDA approved for intraocular surgery and is available in ready-to-use preloaded syringes for cataract procedures (VisionBlue, Dutch Ophthalmic USA). The dye is injected onto and painted over the anterior lens capsule under an air bubble. This produces a blue stained capsule that is clearly identifiable throughout surgery. In addition to cases of a poor red reflex, capsular dyes are extremely helpful in cases of weak zonules. The use of dye reduces the risk of capsule-related complications because any radial tear or shift of the capsular bag is readily apparent from the clearly outlined capsulorhexis.
Retinal surgery: Trypan blue is also a helpful aid for posterior segment surgeons and is utilized for retinal procedures. Visualization of membranes overlying the retina can be difficult, so trypan blue 0.15% ophthalmic solution (MembraneBlue, Dutch Ophthalmic USA) is useful for identifying and delineating them to allow complete removal. The dye stains the posterior hyaloid, internal limiting membrane, and epiretinal membranes blue, making these structures highly visible against the unstained retina. This facilitates macular hole and macular pucker surgery, and makes these procedures safer.
Trypan blue now has a well-established role in ocular surgery. It is readily available, simple to use, and extremely effective. There is no reason to struggle with poor visualization any more.