BLOG: FLACS considerations in post-vitrectomy eyes
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In any eye with a history of retinal surgery, it is important to obtain medical records to determine whether a gas bubble or silicone oil was placed during the vitrectomy because these can have different implications for cataract surgery.
I always look for silicone oil bubbles on the endothelium on OCT imaging during the femtosecond laser portion of the surgery, especially if the history is unclear.
Figure 1. OCT imaging with FLACS shows a posterior capsular defect that was created during a prior pars plana vitrectomy in this eye, which clearly increases the risk for cataract surgery and changes the surgery plan.
Source: Jared Younger, MDIn one memorable case, I raised the capsulotomy settings to the maximum power (10 µJ) in an unsuccessful attempt to get through silicone oil bubbles, resulting in a partial capsulotomy that had to be manually completed with Utrata forceps. The next time I encountered silicone oil bubbles, I simply suppressed the capsulotomy creation and continued to use the laser only to make arcuate and corneal incisions.
The integrated 3D OCT imaging on the Catalys laser (Johnson & Johnson Vision) is helpful in providing advance information for the surgeon to conduct both the laser and the phaco portions of cataract surgery more safely in post-vitrectomy eyes. During imaging, I pause and look carefully for any posterior capsular defect or localized posterior subcapsular cataract that would indicate the need to increase the posterior safety margin for laser fragmentation to protect the posterior capsule. Evidence of a posterior cataract also makes me suspect an iatrogenic capsular defect, such as this vitrector divot (Figure). In a weakened capsule, femtosecond gas formation increases the risk for extending the defect, so it is better to suppress the fragmentation step altogether.
Although a prior vitrectomy can make cataract surgery more challenging, I find it beneficial to use the femtosecond laser in these cases because it confers three advantages over a manual procedure:
1. A pars plana vitrectomy can alter the chamber fluidics, making a manual capsulotomy more difficult. With a deeper anterior chamber or a softer eye, the lens may be more mobile. In contrast, FLACS allows me to make a capsulotomy that is faster and more consistent than a manual capsulorrhexis.
2. The OCT imaging is invaluable to the phaco portion of the case, as well. There have been many situations in which everything looked great preoperatively, only to discover previously unknown posterior lens or capsule defects that lead me to change my approach. For example, I might decide not to perform a full hydrodissection, or I might rely on bimanual irrigation and aspiration to help keep the anterior chamber stable.
3. Lens fragmentation, when indicated, can be useful in a post-vitrectomy eye. The lens and anterior chamber are less stable once the vitreous has been removed, so by pre-softening the lens, you can make the case safer by reducing the amount of ultrasound energy required to emulsify the lens.
FLACS can be safe and beneficial in challenging post-vitrectomy eyes, provided the surgeon takes the time to consider the history and imaging carefully.
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