Metabolic insult from silicone oil exposure can cause lens epithelial cells to undergo fibrous metaplasia, making the lens capsule resistant to tearing. Instead of persisting in trying to initiate a tear, surgeons should use an instrument to cut through the fibrotic material. This non-standard approach for opening the capsule recognizes potential for capsular fibrosis in eyes filled with silicone oil.
Take-Home: Metabolic insult from silicone oil exposure can cause lens epithelial cells to undergo fibrous metaplasia, making the lens capsule resistant to tearing. Instead of persisting in trying to initiate a tear, surgeons should use an instrument to cut through the fibrotic material. This non-standard approach for opening the capsule recognizes potential for capsular fibrosis in eyes filled with silicone oil.
Reviewed by Michael A. Mahr, MD
Rochester, MN-Chronic exposure to silicone oil can result in fibrous pseudometaplasia of lens epithelial cells that can make it impossible to initiate the capsulorhexis tear during cataract surgery.
Surgeons who encounter this situation should abandon their standard capsulorhexis technique and create the anterior capsule opening, instead using an instrument for cutting through the toughened tissue, said Michael A. Mahr, MD.
“Surgeons should not hesitate to cut the capsule due to concern about causing a radial tear because the good news is: a capsule that won’t intentionally tear because it is fibrotic is also less likely to unintentionally tear,” said Dr. Mahr, assistant professor of ophthalmology, Mayo Clinic, Rochester, MN. “On the other hand, surgeons should recognize that continued effort to tear the capsule is risky as the stress can lead to zonular damage or some other problem.”
Dr. Mahr spoke from personal experience with a patient who was referred for surgery for a white cataract. The patient had undergone vitreoretinal surgery eight years earlier for a giant retinal tear with pars plana vitrectomy, endolaser, scleral buckle, and placement of silicone oil that was never removed.
When the flap would not tear, Dr. Mahr instead used micro-scissors to cut and amputate a series of flaps in the capsule to create the capsulotomy. Because the posterior capsule was also white and opacified, he initiated an opening by puncturing the capsule with a bent needle and completed the posterior capsulotomy using a vitrector.
“Opening the posterior capsule was necessary to allow visual rehabilitation in this patient and would also be needed for silicone oil removal,” Dr. Mahr explained. “I was unsure about how effective Nd:YAG laser capsulotomy would be in this situation, and so we chose to open the posterior capsule during the cataract procedure instead.”
Fibrous transformation of lens epithelial cells in phakic eyes filled with silicone oil was described in a paper published by Spraul et al. [Graefes Arch Clin Exp Ophthalmol. 2002;240(10):829-834.] The investigators reported findings from histological evaluation that showed spindle-shaped cells resembling fibroblast that were surround by basement membrane and associated with collagen fibrils.
“The basement membrane is a feature of epithelial cells and the collagen fibrils are a feature of fibroblasts,” Dr. Mahr said. “When we are trying to make the rhexis in an eye with this fibrous pseudometaplasia, we are trying to tear collagen connective tissue that has become ligament- or tendon-like rather than basement membrane.”
Capitalizing on the change
Dr. Mahr proposed that lens epithelial cell fibrous metaplasia might also occur in other scenarios, such as after unintentional posterior capsule penetration during posterior vitrectomy or intravitreal injections. Considering that possibility, there might be a safety advantage for delaying cataract surgery in those situations.
“With sufficient time after the iatrogenic insult, perhaps over a period of months or longer, and given an adequate capsular scaffolding, the fibrous metaplastic phenomenon may allow for the formation of a focal, more localized pseudocapsular plaque,” Dr. Mahr explained. “The plaque can be thought of as a capsular bandage that would potentially provide mechanical integrity to a compromised posterior capsule that would otherwise be at high risk for radializing.”
Michael A. Mahr, MD
This article is based on a presentation given by Dr. Mahr at the 2016 ASCRS Annual Meeting. He has no relevant financial interests to disclose.