Glaucoma and cataracts have a similar demographic, and the issue of combined surgery comes up frequently. Three types of patients are often considered: (1) those with uncontrolled glaucoma and visually significant cataracts; (2) those with well controlled glaucoma and visually significant cataracts; and (3) those with uncontrolled glaucoma and subclinical lens opacities.
Many patients with uncontrolled glaucoma and visually significant cataracts benefit from a combined procedure. The cataract extraction adds a little time and results in slightly higher postoperative pressures as compared with trabeculectomy alone1,2. However, if the cataract procedure is performed later, there is on average a slight increase in pressure following the second surgery, which probably negates this benefit3. Separate glaucoma and cataract surgeries are occasionally warranted. If visual fields are progressing, but the progression is not clearly due to glaucoma, a cataract extraction followed by repeat visual field testing may be preferred. If immediate pressure control is a priority, glaucoma surgery alone may be preferred initially, followed by cataract extraction at a later date.
For those with apparently well controlled glaucoma and visually significant cataracts, cataract surgery alone can often be performed. Glaucoma surgery involves additional risk, office visits, activity limitations, holding anticoagulant and antiplatelet therapy, and possibly slightly decreased visual acuity; thus, glaucoma surgery should only be performed when indicated. The patient should be carefully questioned as to their tolerance of their medications and any barriers to compliance. With advanced visual field defects threatening fixation, early postoperative pressure spikes may be a concern. A concurrent filtration surgery may decrease the incidence of post-cataract extraction pressure spikes; however, due to blood or fibrin at the trabeculectomy site, viscoelastic retention, or tight flap closure, the pressure may still be high on the first postoperative day. The risk of a “snuff out” is not eliminated by a combination surgery, and may occur even without a documented pressure spike. If cataract surgery alone is contemplated, postoperative use of topical and systemic aqueous suppressants may decrease the incidence and severity of postoperative pressure spikes4,5. Thorough viscoelastic removal is indicated, and the pressure should be monitored closely and treated aggressively postoperatively.
For patients with uncontrolled glaucoma and early lens opacities, visual functioning should be carefully assessed, including reading and day and night driving. Acuity should be tested in dark and light conditions. Cataract may progress after glaucoma surgery, sometimes rather rapidly. Cataract surgery at a later date adds psychological and physical stress for the doctor and patient. Complications such as aqueous misdirection are more difficult to address in the phakic patient. Cataract extraction may be helpful in following optic nerve structure and function as well as diagnosing and treating retinal diseases. Whenever cataracts are visually significant, a combined procedure may be preferred. Otherwise, the benefits of a slightly, if only temporarily, lower pressure may suggest filtering surgery alone.
References:
1 Park HJ, Weitzman M, Caprioli J. Temporal corneal phacoemulsification combined with superior trabeculectomy. A retrospective case-control study. Arch Ophthalmol. 1997 Mar;115(3):318-23.
2 Kleinmann G, Katz H, Pollack A, Schechtman E, Rachmiel R, Zalish M. Comparison of trabeculectomy with mitomycin C with or without phacoemulsification and lens implantation. Ophthalmic Surg Lasers. 2002 Mar-Apr;33(2):102-8.
3 Swamynathan K, Capistrano AP, Cantor LB, WuDunn D. Effect of temporal corneal phacoemulsification on intraocular pressure in eyes with prior trabeculectomy with an antimetabolite. Ophthalmology. 2004 Apr;111(4):674-8.
4 Rainer G, Menapace R, Findl O, Sacu S, Schmid K, Petternel V, Kiss B, Georgopoulos M. Effect of a fixed dorzolamide-timolol combination on intraocular pressure after small-incision cataract surgery with Viscoat. J Cataract Refract Surg. 2003 Sep;29(9):1748-52.
5 Lewen R, Insler MS. The effect of prophylactic acetazolamide on the intraocular pressure rise associated with Healon-aided intraocular lens surgery. Ann Ophthalmol. 1985 May;17(5):315-8.
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