Intraoperative floppy iris syndrome may be possible after DMEK

Cases of IFIS have been seen in patients who previously underwent 'phakic DMEK.'

Issue: January 25, 2019

ByJack S. Parker, MD, PhD

Intraoperative floppy iris syndrome is a well-known and highly feared entity. By some measures, it is the most common difficulty encountered during cataract surgery and a significant risk factor for severe intraoperative complications, including posterior capsule rupture, zonular dialysis and endophthalmitis.

Typically, intraoperative floppy iris syndrome (IFIS) is associated with prior Flomax (tamsulosin, Boehringer Ingelheim) use. Recently, however, we have come to appreciate another association that appears to be at least as strong, namely, prior Descemet’s membrane endothelial keratoplasty.

Increasingly, DMEK may be performed for endothelial dysfunction in phakic eyes, either in young patients with clear crystalline lenses or in standard populations with lenticular opacities that prefer staged surgery (endothelial transplantation first, then cataract surgery second) as a means of achieving a better refractive end result. Although DMEK in phakic eyes may be regarded as a more technically challenging procedure, as the technique spreads and surgeons gain additional experience, “phakic DMEK” may likewise continue to grow in popularity. As a result, it may become correspondingly common to encounter patients who require cataract extraction and have a history of DMEK.

Over the years, in our practice, we have observed a strong tendency in our patients under these conditions to manifest significant IFIS at the time of their cataract surgery, despite the absence of any documented history of tamsulosin use. Frequently, iris abnormalities, especially posterior synechiae, are evident (Figure 1). Poor dilation is common, often necessitating use of pupillary expansion devices. Moreover, the iris tone may be distinctly abnormal, notably “floppy” and prone to prolapse, as seen in patients with traditional tamsulosin-induced IFIS. Speculatively, these changes in the appearance and behavior of the iris may stem from iris stromal atrophy, induced by the gas bubble left behind at the end of the DMEK surgery.

These findings impress us as significant for three reasons.

**Figure 1.** Intraoperative stills obtained during the time of cataract surgery, demonstrating the variable extent of posterior synechiae resulting from prior phakic DMEK (a to c). During subsequent surgical steps, IFIS may become manifest, including hydrodissection (d) and phacoemulsification (e). In patients who receive toric lenses, poor dilation may render alignment marks difficult to visualize, problematizing accurate positioning (f).

First, they suggest that staged surgery (phakic DMEK first, then cataract surgery second) may entail additional risks because the cataract surgery is likely to be more complicated than if the two surgeries were performed simultaneously. This is particularly important because staged surgery is now most likely to be recommended for young patients and for those interested in specialty IOLs (toric or multifocal), ie, the two populations in which intraoperative complications would be most feared. For toric patients, poor pupillary dilation may also problematize proper lens positioning along the correct axis, as well as the diagnosis and correction of misaligned or rotated lenses.

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Second, the findings suggest that DMEK surgeons may consider exercising more caution in the duration and extent of the gas fill they leave to support their endothelial grafts if indeed bubble-induced iris stromal atrophy is proven as the culprit mechanism.

Third, especially in this current environment of comanaged care, it may be significant for general ophthalmologists and cataract surgeons to be alert to the possibility of unexpected intraoperative difficulties in patients with prior DMEK.

A formal study of the prevalence and mechanism of this observed tendency toward IFIS in patients with prior DMEK is currently underway. Meanwhile, we would like to draw attention to this apparent association, and caution DMEK and cataract surgeons alike about a possible and previously unrecognized risk for phakic DMEK.

References:
Chang DF, et al. J Cataract Refract Surg. 2005;doi:10.1016/j.jcrs.2005.02.027.
Jan Teper S, et al. Cent European J Urol. 2011;doi:10.5173/ceju.2011.02.art2.
Kaczmarek IA, et al. Int Ophthalmol. 2018;doi:10.1007/s10792-018-0840-3.
Vollman DE, et al. Am J Ophthalmol. 2014;doi:10.1016/j.ajo.2014.02.052.

For more information:
Jack S. Parker, MD, PhD, and John S. Parker, MD, can be reached at Parker Cornea, 700 18th St. South, Suite 503, Birmingham, AL 35233; email: jack.parker@gmail.com and john.jsp26@gmail.com.

Disclosures: The authors report no relevant financial disclosures.