Hydrodissection is performed to separate the peripheral and posterior cortex from the underlying posterior lens capsule. In addition to loosening the lens–cortex complex, this procedure facilitates nucleus rotation during phacoemulsification and hydrates the peripheral cortex, making it easier to aspirate after nucleus removal.
In this procedure, the surgeon places a bent, blunt-tipped 25- to 30-gauge cannula or flattened hydrodissection cannula attached to a 3- to 5-mL syringe under the anterior capsule flap. While carefully lifting the capsular flap, the surgeon injects balanced salt solution in a radial direction. Exerting gentle posterior pressure on the nucleus will express posterior fluid and prevent fluid pressure from rupturing the posterior capsule. Gentle irrigation continues until the surgeon sees a wave of fluid moving under the nucleus and across the red reflex (Video 8-2). In mature cataracts or in cases without a red reflex, careful hydrodissection continues until nucleus rotation can be performed. Irrigation in the subincisional area may require a right-angled or J-shaped hydrodissection cannula.
Hydrodissection. Courtesy of Linda Tsai, MD.
If the nucleus is displaced into the anterior chamber, it can be reposited into the posterior chamber with injection of OVD and application of slight posterior pressure. Alternatively, a supracapsular phacoemulsification technique may be selected in this situation. Hydrodissection is riskier after a can-opener capsulotomy has been performed, with weakened zonular fibers, or with a posterior polar cataract (see Chapter 12 for further discussion of posterior polar cataracts).
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.