The USA Flag Sign is seen when we use a femtosecond laser to assist in phaco of a white cataract. (scroll down to see the full video)
You’ve heard of the Argentinian Flag Sign for white cataract phaco surgery, but what is the USA Flag Sign? The colors of the USA flag are red, white, and blue and we see these same colors when we use a femtosecond laser to create the capsulorhexis in a patient with a white cataract, we see the red (sub-conjunctival ring hemorrhage from the femto suction ring), white (the cataract), and blue (the Trypan dye used to stain the capsule).
The femtosecond laser can be a useful tool for cataract surgery. In routine cataract cases, the benefit is typically mild and in expert hands, may not provide a meaningful improvement over manually performed steps of surgery. For this reason, in most of my cataract cases, I do not find myself using the femtosecond laser during cataract surgery. But in certain challenging cataract cases, the femto laser can be helpful in producing a better outcome and avoid certain complications.
Capsulorhexis Creation in White Cataracts
In the vast majority of cataract surgeries, an experienced surgeon can perform continuous, curvilinear, centered capsulorhexis with consistency. However, in cases where there is poor visualization of the capsule, an intumescent cataract, or significantly weak zonular structures, the femtosecond laser can assist the surgeon by making the anterior capsular opening in just a second or two, prior to making the first incision into the eye.
For intumescent white cataracts, the challenge is that the lens capsular bag is filled with the opaque and liquefied cortex material. This creates an intra-lenticular pressure that is higher than the anterior chamber pressure in manual surgery. This forward push can cause the capsulorhexis to run out and result in the so-called Argentinian Flag Sign, which is when the blue-stained capsule splits down the middle so that the resultant appearance of blue-white-blue resembles the Argentinian flag. This is a precarious situation because if the capsular tear extends to posterior, it can result in displacement of the lens nucleus and prolapse of vitreous.
In manual surgery, this can be mitigated by keeping the anterior chamber pressure higher than the intra-lenticular pressure by inflating it with viscoelastic and using only incisions of 1 mm or smaller. The femtosecond laser also can maintain the pressure within the anterior chamber by applying suction to the patient interface ring and avoiding incisions into the anterior chamber during the firing of the laser. Once the laser-based steps are completed, a paracentesis can be made into the anterior chamber which is then infused with Trypan blue dye and then filled with viscoelastic (Figure 1). The anterior capsule can then be lifted with forceps in a gathering motion to ensure that no tags of capsular attachment remain (Figure 2).
Figure 1: The anterior capsular was stained with typan blue dye and is now being filled with viscoelastic. The outline of the femto-created anterior capsule opening can be seen as it absorbs the blue dye.
Figure 2: The anterior lens capsule can be grasped with forceps and tented up to ensure that there are no residual attachments.
The femto-second laser encounters difficulty with placing energy within a lens nucleus that is very opaque, thereby limiting the effectiveness of the laser-based nucleus fragmentation or softening patterns. In the case of our patient with the dense, white cataract, the lens nucleus was disassembled using the vertical quick-chop technique. Once the first quadrant is removed, the remaining lens nucleus can be further fragmented and then phaco-aspirated from the eye. (see the video below to learn this technique)
Using a femtosecond laser to perform the anterior capsular opening can be useful since it can be accomplished in a closed eye in just a few seconds, but, admittedly, it is a very expensive option (a femtosecond laser can cost more than US$500,000 with additional costs per use). Los Angeles is a diverse city: for my Beverly Hills patients who can afford to pay the fees, we can use a femtosecond laser; for the other patients who have more financial constraints, we can use the manual, double-capsulorhexis technique described in the previous video. Both patients will have an excellent outcome.
All text, figures, pics, and videos are © 2018 Uday Devgan MD. All rights reserved.