In eyes with dense, brunescent cataracts, surgical manipulation increases the risks of iris trauma, zonular tearing, capsular rupture, vitreous loss, and the dropping of lens fragments into the posterior segment. The increased ultrasound energy required for phacoemulsification of dense lenses increases the risk of endothelial trauma and wound burn. Creation of a larger capsulorrhexis is helpful because it allows the surgeon to perform the maneuvers that are necessary to minimize these complications. Thorough hydrodissection and hydrodelineation of the nucleus facilitate smooth rotation during phacoemulsification. When an initial groove is made in the hard nucleus, it is important that the surgeon make a deep and even pass. The aim is to crack the nucleus without leaving interdigitations, which would interfere with removal and potentially result in rupture of the posterior capsule. Viscodissection helps separate sticky cortical attachments that impede rotation. If the surgeon uses excessive mechanical force on a nucleus that does not freely rotate, zonular dialysis may result from transmittal of that force to the capsular bag. Mechanical segmentation techniques for nucleus disassembly, such as vertical and horizontal chopping, require less ultrasound energy and may induce less zonular stress than the “divide and conquer” method (see Chapter 8). Familiarity with multiple techniques, and the ability to switch from 1 technique to another as the situation requires, enables the surgeon to minimize complications.
If phacoemulsification ceases to be appropriate for lens removal, conversion to an extracapsular technique can be considered. The surgeon may proceed through the corneal incision, enlarging it to permit passage of the cataract and lens implant. Alternatively, the surgeon may close the corneal wound and make a new, larger corneoscleral incision. Often, a corneoscleral incision is more stable than a large corneal wound and induces less astigmatism postoperatively.
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.