February 04, 2016
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Prompt surgical removal of retained lens fragments recommended

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Surgeons should consider prompt surgical removal of retained lens fragments from the anterior chamber after otherwise uncomplicated cataract surgery, according to a study.

Although retained lens fragments are rare, occurring in less than 1% of routine cataract surgeries, nearly every cataract surgeon has experienced such a case, the study said.

It is possible that the frequency of retained lens fragments in the anterior chamber may significantly increase with new lens fragmentation patterns available on femtosecond laser platforms. However, there is a lack of data relating to the clinical features, treatments and outcomes of diagnosed cases.

Zachary J. Zavodni, MD, and colleagues conducted a retrospective, interventional case series, published in the American Journal of Ophthalmology, that reviewed 54 eyes diagnosed with retained lens fragments in the anterior chamber after uncomplicated cataract surgery.

“Retained lens fragments should be high on the differential diagnosis for persistent post-cataract surgery iritis and corneal edema,” he said. “Our data suggest that delay in diagnosis, and subsequently a longer time to surgical extraction, may increase the chance of developing permanent endothelial cell damage.”

Of the 54 patients in the study, the majority were diagnosed using slit lamp examination; however, 13% of cases required gonioscopy for visualization of the lens fragments. Therefore, Zavodni strongly recommended performing gonioscopy on all patients with unexpected postoperative corneal edema or anterior inflammation.

“While most retained lens fragments can be visualized under direct slit lamp illumination, our data and that of previous studies suggest that approximately 15% of cases would be missed without gonioscopic exam,” he said. “This is especially true for smaller lens fragments hiding in the angle and cases of dense inferior quadrant edema where direct visualization is difficult.”

After examination, the retained lens piece was located in the inferior anterior chamber or inferior angle in all cases.

In the data set, 16% of lens fragments were described as “nuclear” on examination, 11% were “epinuclear,” and 22% were “cortical,” while 50% were not qualified and simply noted as “lens fragment.”

At the time of diagnosis, 81% of eyes had documented anterior chamber inflammation, 11% of cases had IOP greater than 25 mm Hg, and two eyes had cystoid macular edema.

Corneal edema

Forty-three percent of eyes with a retained lens fragment presented with corneal edema, but seven additional eyes went on to develop corneal edema after the time of diagnosis, for a total of 30 eyes with corneal edema at any time point postoperatively.

The corneal edema localized to the inferior quadrant in 18 of the 30 eyes, but the tendency for inferior edema was higher among patients with corneal edema who were diagnosed after postoperative day 1.

Controversial theories for corneal edema related to unencapsulated lens material include mechanical trauma vs. an immune-mediated process in which the immune response directed against exposed lens antigen also attacks the endothelium.

“Multiple studies have demonstrated a foreign body granulomatous reaction against retained nuclear lens material. Under the immune hypothesis, it is unclear why there would be a predilection for endothelial cell compromise in the inferior quadrant unless the immune response remains localized or concentrated around an inferiorly located lens fragment,” Zavodni said.

Arguing against this regional theory is the observation that corneal edema can result from retained lens fragments that remain in the posterior chamber. Meanwhile, retained cortex within the capsular bag after uncomplicated cataract surgery typically does not seem to incite corneal edema.

“This final observation may argue against an immune-mediated process or may highlight the importance of lens fragment density (cortex vs. nucleus) and lens fragment encapsulation/compartmentalization as factors influencing the amount of secondary inflammation and corneal edema. Currently, a cogent rationalization for these differing phenotypes remains elusive,” Zavodni said.

Treatments

Upon diagnosis, 44% of patients were initially managed with topical corticosteroid medication, but in all 54 cases the lens fragment was eventually removed surgically.

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The reasons for conversion to surgical treatment were worsening or persistent corneal edema in 63% of cases and unresolving anterior chamber inflammation in 37% of cases, Zavodni said.

“These results were somewhat unexpected, especially considering that many of the fragments were explicitly noted not to be nuclear in origin,” he said. “However, in our experience, a confident differentiation between nuclear and epinuclear/cortical lens fragments can be very difficult, particularly when a diagnosis is made several days to weeks after cataract surgery and the fragment has undergone hydration.”

Mean time to removal of the lens fragment from the date of cataract surgery was 70 days, with a mean difference of 18 days between patients with and without corneal edema, which was not statistically significant.

Of the 30 eyes with corneal edema, five cases did not resolve after fragment extraction, and three eyes eventually received an endothelial keratoplasty.

“This finding suggests an increased risk of permanent endothelial damage the longer a lens fragment remains in the anterior chamber,” Zavodni said.

Best corrected visual acuity improved from an average of 20/51 before lens fragment removal to 20/28 after surgical extraction (P < .00001).

Future studies

While this study evaluated preoperative patient characteristics such as axial length, tamsulosin use and presence of corneal arcus as possible risk factors for lens fragment retention, Zavodni would like to further evaluate intraoperative surgical factors including viscoelastic type, phacoemulsification technique and phacoemulsification delivery.

“Since our data were collected, the most notable change in cataract surgery has been the integration of femtosecond laser-assisted surgery,” he said. “It is certainly possible that the type of lens fragmentation pattern may influence the incidence of retained lens pieces, and this should be studied moving forward.” – by Kristie L. Kahl

Disclosure: Zavodni reports no relevant financial disclosures.