The management of co-existing cataract and glaucoma requires an assessment of the risk of worsening of the glaucomatous optic neuropathy should there be an IOP rise postoperatively. In general, a patient with significant glaucomatous optic neuropathy and visual field loss with pressures that are uncontrolled or that require more than 2 topical medications for control should have combined cataract extraction and trabeculectomy.
Another issue to be considered is the likelihood of failure of the trabeculectomy, particularly in patients who have secondary glaucoma, such as increased episcleral venous pressure, inflammatory glaucoma, or, as in this case, ICE syndrome. Glaucoma in such cases is probably best managed with an aqueous shunt.
The patient in this case requires 4 topical medications for IOP control yet does not have evidence of glaucomatous optic neuropathy. Although cataract surgery often lowers IOP, it would probably not do so in this case in which the mechanism is that of secondary angle closure and membrane proliferation across the drainage angle structures.
Cataract surgery alone should not permanently increase IOP, however. Therefore, this eye may be approached by cataract surgery alone, taking precautions to prevent a postoperative IOP rise, such as by instilling an alpha2 andrenoreceptor agonist (e.g., brimonidine tartrate [Alphagan®] or apraclonidine [Iopidine®]) at the beginning and end of the procedure, a drop of levobunolol (the only beta adrenoreceptor antagonist shown to prevent IOP increases after cataract surgery), and 500 mg of acetazolamide (Diamox® sequel) by mouth a few hours after surgery. Extra precautions should be taken to remove all viscoelastic agent from the eye at the conclusion of the procedure. The addition of a long-acting miotic, such as intraocular carbachol (Miochol®), would not be expected to lower pressure in this type of secondary glaucoma.
The patient should be counseled that continued pressure-lowering therapy will be required after surgery, most likely at the same level as before, and that there is a possibility that additional surgery will be necessary to control pressure in the future. She should also be advised that there is a risk of a pressure rise soon after surgery. Should the pressure become uncontrolled or evidence of glaucomatous optic neuropathy become manifest any time following surgery, an aqueous shunt could be placed.
If the patient expresses concern about the need for 4 glaucoma medications postoperatively or the risk of a postoperative IOP rise, combined phacoemulsification via a superior scleral tunnel approach with placement of an aqueous shunt in the superotemporal quadrant can be performed.