Shallow or Flat Anterior Chamber
Intraoperative shallowing of the anterior chamber is discussed in Chapter 10.
During the postoperative period, a flat anterior chamber may permanently damage ocular structures. Prolonged apposition of the iris to angle structures can result in PAS formation and chronic angle-closure glaucoma. Corneal contact with the vitreous or an IOL can result in endothelial cell loss and chronic corneal edema. Postoperative shallow or flat anterior chambers can be classified according to their etiology and level of IOP (Table 11-2).
Patients with ocular hypotension (IOP below 10 mm Hg) and a shallow chamber may be asymptomatic, especially when a leaking incision is plugged by iris incarceration, allowing re-formation of the anterior chamber. Slow or intermittent leaks may still allow a formed anterior chamber. Performing a Seidel test and carefully comparing the chamber depth in the surgical eye with that of the fellow eye may help the surgeon identify subtle cases of incisional leaks. (For a discussion of the evaluation and management of an incisional leak, see the section “Incision and wound complications” earlier in this chapter.)
Surgical exploration with re-formation of the anterior chamber and repair of the incision is indicated if no improvement occurs within 24–48 hours, if an obvious wound gape is present, if the iris is prolapsed out of the incision, or if intraocular structures such as the IOL are in contact with the corneal endothelium.
Pupillary block with a shallow anterior chamber may occur from various causes. Early, it may follow a resolved incision leak. Later, postoperative uveitis with iridovitreal or iridocapsular synechiae may be the cause. Failure to perform a peripheral iridectomy after placement of an anterior chamber IOL (ACIOL) may also be associated with early or late postoperative pupillary block. When initial attempts at pupillary dilation fail to deepen the anterior chamber and lower the pressure, a laser peripheral iridotomy is usually effective.
Table 11-2 Causes of Postoperative Flat or Shallow Anterior Chamber According to IOP Level
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.