Anterior Capsule Fibrosis and Phimosis
Capsular fibrosis is associated with clouding of the anterior capsule. If a substantial portion of the IOL optic is covered by the opaque anterior capsule, including portions exposed through the undilated pupil, the patient may experience symptoms such as glare, especially at night because of physiologic mydriasis in darkness, or a perception that vision has become cloudy or hazy. The term capsular phimosis describes the postoperative contraction of the anterior capsule opening as a result of circumferential fibrosis. Phimosis produces symptoms similar to and often more pronounced than those of fibrosis alone.
Figure 11-14 Illustration of Nd:YAG laser anterior capsulotomy. Multiple radial anterior capsulotomies (arrows) can relieve anterior capsule phimosis and traction on the zonular fibers.
(Illustration by Christine Gralapp.)
Fibrosis and anterior capsule contraction occur more frequently with smaller capsulorrhexis openings, underlying pseudoexfoliation syndrome, and abnormal or asymmetric zonular support (eg, penetrating or blunt trauma, Marfan syndrome, or surgical trauma). Anterior capsule contraction may contribute to late pseudophacodonesis or in-the-bag IOL subluxation due to stress on the zonular apparatus.
Anterior capsule contraction, but not PCO, may be reduced with anterior capsule polishing to remove residual lens epithelial cells. Capsular phimosis can be treated with several radial Nd:YAG laser anterior capsulotomies to release the annular contraction, reduce the traction on the zonule, and enlarge the anterior capsule opening (Fig 11-14). This procedure is performed similar to Nd:YAG laser posterior capsulotomy, with care taken to not defocus too far posteriorly and damage the underlying IOL with laser pitting. In general, the anterior capsule tissue or a fibrotic ring is tougher and thus requires more laser power than does the posterior capsule.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.