When cataract surgery is being considered in a patient with glaucoma, it is important to assess how well the glaucoma is controlled preoperatively. It can be challenging to predict the visual outcome in an eye with both cataract and glaucoma because both conditions can contribute to blurred vision, and the patient’s visual symptoms may not be exclusively attributable to 1 condition or the other. An advanced visual field defect may limit vision improvement after cataract surgery. In contrast, an advanced cataract may exaggerate a mild visual field abnormality (Fig 12-10). Surgical options include cataract surgery alone, combined cataract and glaucoma surgery, and staged procedures of glaucoma surgery (eg, trabeculectomy or drainage device) followed by cataract surgery in a subsequent session. Uncomplicated phacoemulsification alone may lower the long-term IOP by 10%–34%. Minimally invasive glaucoma surgery (MIGS) can be combined with cataract extraction to further reduce IOP in a blebless, conjunctiva-sparing manner. Small-incision cataract surgery with a clear corneal approach minimizes conjunctival damage; this is essential if filtering surgery is required in the future. In an eye with a functioning filtering bleb, a small incision in a temporal or superotemporal location makes cataract surgery straight-forward and is less likely to compromise IOP control. Issues influencing determination of the surgical approach include
desired postoperative IOP
degree of damage to the optic nerve and visual field
number of medications required to control IOP
expected patient adherence to the medication regimen
potential adverse effects of the medications
potential impact on quality of life
Figure 12-10 Visual field before and after cataract surgery. Media opacity, such as cataract, can impair the visual field. A, An abnormal Humphrey visual field in a glaucoma patient with a dense cataract. B, Improved Humphrey visual field following cataract removal and lens implantation.
(Courtesy of Lisa Rosenberg, MD.)
Surgical decision making in the glaucomatous eye and combined cataract and glaucoma surgery are discussed in BCSC Section 10, Glaucoma.
Most surgical challenges in eyes with both glaucoma and cataract are not unique. For instance, zonular compromise and phacodonesis can complicate capsulorrhexis creation and lens removal in eyes with traumatic or pseudoexfoliation glaucoma. When a patent peripheral iridotomy (PI) is performed, the surgeon may inadvertently hydrate the vitreous; and caution is advised while injecting dye into the AC to avoid vitreous staining by injecting dye through the PI. Uveitic glaucoma and miotic therapy may limit pupillary dilation and increase the risk of postoperative macular edema. After surgery, the IOP can increase, owing to retained OVDs or inflammation, and pressures rise to a higher level in glaucomatous eyes with reduced outflow through the trabecular meshwork.
The use of topical prostaglandin medication may be associated with postoperative cystoid macular edema (CME), although there are few proven cases. In part, this is because clinically significant CME after uncomplicated phacoemulsification occurs only in rare instances. In cases of early postoperative CME, discontinuation of the prostaglandin is advisable to determine whether this medication is contributing to the edema.
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.