2020–2021 BCSC Basic and Clinical Science Course™
11 Lens and Cataract
Chapter 12: Preparing for Cataract Surgery in Special Situations
Altered Lens and Zonular Anatomy
Posterior Polar Cataract
A weak or absent area of the posterior lens capsule in the region of a posterior polar opacity places the eye at increased risk of capsular rupture during surgery. Accordingly, the surgeon should avoid exerting excessive pressure within the capsular bag or on the posterior capsule. Complete hydrodissection is also avoided because of possible tearing of the capsule directly under the opacity. Instead, the following procedure is undertaken:
Deliver small volumes of fluid around the cortex up to, but not across, the opacity.
Perform gentle hydrodelineation, leaving a generous amount of epinuclear bowl in which to mobilize the nucleus and protect the capsule.
Maintain the AC depth and limit fluctuations in IOP by low irrigation and aspiration.
After the nucleus is removed, OVD is used for viscodissection of the epinucleus from the capsular bag. The posterior polar opacity is removed last; viscodissection can be performed for this step as well. If the central portion of the posterior capsule is missing, filling the capsular bag with OVD before removing the irrigating phaco handpiece from the eye will stabilize the chamber for lens insertion. Alternatively, if the posterior polar opacity is very adherent, it can be left in place, assessed for its impact on vision postoperatively, and treated with laser capsulotomy, if indicated. After the IOL is placed in the capsular bag in an uncomplicated procedure, movement of the bag can be minimized with slow and gentle OVD removal.
Figure 12-7 Zonular dehiscence or absence is common in iris coloboma. A, Coloboma of the iris with nuclear cataract. Absent or abnormal zonular fibers correlate with the area of the iris defect. A preoperative evaluation of associated posterior segment abnormalities is an important way to assess vision potential. B, Capsular tension ring with coloboma diaphragm. Note: This device is not approved by the US Food and Drug Administration; compassionate use is available.
(Part A courtesy of Robert S. Feder, MD; part B illustration by Natalie A. Afshari, MD.)
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.