Thorough preparation needed for cataract surgery in eyes with glaucoma

The surgery may be more challenging, but the results are worth it.

Uday Devgan

Cataract surgery in eyes with glaucoma can be more challenging, and these patients may be prone to more postoperative complications. Cataract surgery can also be particularly helpful in many cases of glaucoma because it can resolve crowding of the angle and even provide lower IOP.

Preoperative evaluation

The extent of pre-existing glaucomatous damage, the progression over time and the current control of IOP are all factors that need to be considered. Eyes with damaged optic nerves, as evidenced by increased cupping, may be susceptible to further damage during phacoemulsification, particularly if high infusion pressures are used. Eyes with prior glaucoma drainage surgeries, such as trabeculectomies and tube shunts, will make the fluidics of phacoemulsification less stable because they provide an additional outflow tract. Patients with glaucoma that is poorly controlled need to first address this because cataract surgery is elective and can be delayed until a more appropriate time.

Because glaucoma can limit visual function and because it tends to progress with time, the IOL should provide the highest visual quality and transmit as much light as possible. Choosing an aspheric clear monofocal IOL is a reliably good choice in these patients. Toric and accommodating aspheric designs may also be appropriate depending on the condition. However, multifocal lenses should be avoided when there is significant glaucomatous damage present because the splitting of light can reduce contrast sensitivity and limit visual results.

For the IOL calculations, choosing a target of plano in both eyes is a common approach and is appropriate at all levels of glaucomatous disease. Patients must understand that the cataract surgery will correct only the cataract, and perhaps the refractive error, but it will not be able to reverse the glaucoma damage. And while the IOP can be helped and sometimes even controlled by cataract surgery, this effect may be variable and may not last.

Intraoperative techniques

If the patient has had a prior glaucoma surgery, such as a trabeculectomy, care must be taken not to disturb that site or the conjunctiva near it. For this reason, a clear or near-clear corneal phaco incision is recommended, along with suture closure at the end of the case, because the glaucoma procedure limits the postoperative IOP and may hinder the sealing of sutureless wounds. During the phacoemulsification procedure, the outflow tract of the prior glaucoma surgery can induce anterior chamber instability and surge, which can make capsular rupture more likely. This can be addressed via decreasing the outflow, by using a lower flow rate and viscoelastic to temporarily block egress of fluid via the trabeculectomy, and via increasing the inflow of fluid by raising the bottle height. High IOP can be induced by prolonged higher infusion pressures and by the forces generated during injection of the IOL into the capsular bag, and this may result in acute damage to a frail optic nerve. This can be minimized by balancing the fluidics and slightly enlarging the corneal incision to allow for a more gentle insertion of the IOL.

This eye has a history of pigment dispersion glaucoma with a visible Krukenberg’s spindle on the corneal endothelium, as well as prior radial keratotomy with eight incisions. The cortical spokes of the cataract are seen in this figure; however, the posterior subcapsular plaque is hidden by the lighting. The inset photo shows the optic nerve of the eye, which has significant glaucomatous damage influenced by years of uncontrolled IOP. Images: Devgan U

Cataract surgery is being performed on an eye with a history of glaucoma and a prior trabeculectomy with an active filtering bleb. Care is taken during the cataract surgery to adjust the fluidic settings and to avoid damage to the trabeculectomy site so that it continues to function and control the IOP.

In eyes with a history of glaucoma but no prior glaucoma surgery, corneal phaco incisions are still recommended so that the conjunctiva can be spared in case it is required for a future procedure. Phacoemulsification in these eyes tends to be more typical because the fluidic considerations are similar to routine cataract surgery in normal eyes. The IOL should be placed completely within the capsular bag with the capsulorrhexis overlapping the optic to prevent the optic edges from contacting the posterior iris surface. Placing the IOL in the ciliary sulcus or allowing the optic to rub the iris can induce iatrogenic pigment dispersion, which may worsen the glaucoma. There are surgical options for addressing glaucoma at the time of the cataract procedure with new small-caliber stents, laser treatments or other devices, and this may soon be an essential part of the surgery for these patients.

Postoperative management

Topical and systemic medications can be given to lower IOP after surgery and blunt an acute IOP spike. Retained viscoelastic material, particularly cohesive agents, can clog the trabecular meshwork and the prior trabeculectomy site, which is why thorough removal is important at the end of the cataract surgery. The postoperative inflammation must be controlled, and topical steroids and NSAIDs are often prescribed together. The rate of steroid-induced IOP spikes is also higher in patients with glaucoma, so they should be monitored at close intervals during the postoperative period.

With a thorough preoperative evaluation, careful surgical planning and appropriate intraoperative techniques, cataract surgery can be successfully performed for patients with a history of glaucoma. The cataract surgery can provide better vision, correction of the refractive error, widening of the angle, deepening of the anterior chamber and even better control of IOP.

• Uday Devgan, MD, FACS, FRCS(Glasg), is in private practice at Devgan Eye Surgery in Los Angeles, Beverly Hills and Newport Beach, Calif. He is also chief of ophthalmology at Olive View UCLA Medical Center and associate clinical professor at the UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax 310-388-3028; e-mail: devgan@gmail.com; website: www.devganeye.com.