The Evolving Role of Lens Extraction in Glaucoma Care
Cataract surgery lowers the IOP in eyes with many types of glaucoma.
Cataract surgery is one of the simpler treatments ophthalmologists can offer to glaucoma patients, and it is an option surgeons may need to use often.
In a 2002 article, Friedman et al reviewed 39 articles published between 1964 and 2000 “pertaining to the surgical management of coexisting cataract and glaucoma in adults.” The evidence showed, although weakly in the researchers’ opinion, that cataract surgery alone lowered the IOP 2 to 4 mm Hg for 1 to 2 years after the surgery.1 This finding was supported by other published studies.2-4
Poley et al published a large retrospective review in 2008 showing that cataract surgery strongly affects IOP. The investigators followed up with a prospective trial in 2009. It found that the decrease in IOP after cataract surgery was strongly inversely associated with the preoperative IOP level. The investigators grouped patients into five categories by preoperative IOP level: 29 to 23, 22 to 20, 19 to 18, 17 to 15, and 14 to 5 mm Hg. The final mean IOP reduction at 1 year was 8.5 mm Hg (34%) in the first group, 4.6 mm Hg (22%) in the second group, 3.4 mm Hg (18%) in the third group, and 1.1 mm Hg (10%) in the fourth group. In the fifth group, which had the lowest baseline IOP, the pressure rose 1.7 mm Hg (15%).5,6
Researchers recently published a follow-up study of patients who underwent cataract surgery during the Ocular Hypertension Treatment Study (OHTS). The investigators found that the average decrease in IOP 36 months after the cataract procedure was 16.5% and that 39.7% of eyes had a postoperative IOP that was at least 20% below the preoperative level.7
EYES WITH NARROW ANGLES
Glaucoma specialists are routinely asked to evaluate patients whose eyes have narrow angles. The diagnosis is made on a case-by-case basis but generally involves gonioscopy and ultrasound biomicroscopy or anterior segment optical coherence tomography. Eyes with sufficiently narrow angles, according to the specialist’s criteria, are usually treated with a laser peripheral iridotomy (LPI), and then repeat gonioscopy is performed to confirm sufficient widening of the angle. When laser treatment is not adequate, how to proceed is a gray area. Should the surgeon increase the size of the LPI? Use ultrasound biomicroscopy to look for a plateau iris or other causes? Try a laser peripheral iridoplasty? Perform cataract surgery?
If the angle is persistently narrow after a well-performed LPI and there are no signs of plateau iris or other secondary causes of narrowing, I give the patient two options: iridoplasty or cataract surgery. I myself think cataract surgery is the better way to avoid the chronic narrowing of the angle and the peripheral anterior synechiae that can occur after a long-standing iridoplasty. Cataract extraction lays the problem to rest and generally improves patients’ visual acuity in the process.
It is not uncommon for a patient to be referred to me for worsening primary open-angle glaucoma yet to demonstrate, on evaluation, chronic angle-closure glaucoma (CACG). In my opinion, cataract surgery—plus or minus goniosynechialysis—is the best initial incisional glaucoma surgery for chronic or acute angle-closure glaucoma (ACG) after LPI when the crystalline lens is present.8-11 Phacoemulsification alone will significantly lower IOP,12-15 which will minimize the long-term sequelae of peripheral anterior synechiae and elevated IOP.
Although trabeculectomy alone can successfully address ACG,16 the procedure carries some risk. Moreover, trabeculectomy can always be performed secondarily to cataract surgery if needed. In two separate studies, Tham et al demonstrated that cataract surgery alone can lower the IOP in CACG cases.13,14 The studies covered controlled and uncontrolled CACG and compared cataract surgery alone versus combined with trabeculectomy. In both studies, the combined procedure reduced the IOP and the number of glaucoma medications that patients required to a greater extent, but it did so at the expense of higher complication rates. Given these results, phacoemulsification alone is a reasonable approach to the initial surgical treatment of ACG. The decision, however, should be individualized to the patient and according to the surgeon’s comfort level.
Cataract surgery can be difficult if the eye has a shallow chamber. Ophthalmologists have used different modalities to shrink the vitreous, including the preoperative instillation of mannitol, a Honan balloon, scleral depression, and dry vitrectomy. All of these methods create more space in the anterior chamber. It is important to explain to patients that ACG presents a challenge and that each case may be different.
MICROINVASIVE GLAUCOMA SURGERY
Because many microinvasive glaucoma surgery (MIGS) procedures build on modern cataract surgery’s effect on IOP, they are becoming an increasingly important way to increase glaucoma patients’ probability of IOP success.
Performed with cataract surgery, the Trabectome (NeoMedix), iStent Trabecular Micro-Bypass Stent (Glaukos; Figure), and Hydrus (Ivantis; not available in the United States) have all shown an ability to lower the IOP beyond what the cataract procedure alone can achieve.17,18 Although perhaps not classic MIGS, endocyclophotocoagulation has also proven to be useful at increasing IOP reduction at the time of cataract surgery.19,20
Additional MIGS devices on the horizon are the Cy-Pass Micro Stent (Transcend Medical), the iStent inject and iStent Supra (Glaukos), and the Xen Gel Stent (AqueSys). I do not know how these technologies will fit into the treatment of open- or narrow-angle glaucoma, but the literature and surgeons’ experiences will guide the way.
When examining a glaucoma patient, I now see narrow angles or developing cataracts as an opportunity, not only to improve the patient’s visual acuity, but also to lower the IOP, reduce the burden of medication, or avoid advancing glaucoma drop therapy. No surgical procedure guarantees a certain final IOP level, and I am quite frank about that point during my discussions with patients. All surgeons can offer is an increasing probability of successful IOP reduction based on the available evidence and their personal experience.
Marcos Reyes, MD, is an associate clinical professor in the Department of Ophthalmology, Mason Eye Institute, University of Missouri, Columbia, Missouri. He acknowledged no financial interest in the products or companies mentioned herein. Dr. Reyes may be reached at (573) 882-1029; email@example.com.
- Friedman DS, Jampel HD, Lubomski LH, et al. Surgical strategies for coexisting glaucoma and cataract: an evidence-based update. Ophthalmology. 2002;109(10):1902-1913.
- Mathalone N, Hyams M, Neiman S, et al. Long-term intraocular pressure control after clear corneal phacoemulsification in glaucoma patients. J Cataract Refract Surg. 2005;31:479-483.
- Shingleton BJ, Gamell LS, O’Donoghue MW, et al. Long-term changes in intraocular pressure after clear corneal phacoemulsification: normal patients versus glaucoma suspect and glaucoma patients. J Cataract Refract Surg. 1999;25:885-890
- Shingleton BJ, Pasternack JJ, Hung JW, O’Donoghue MW. Three and five year changes in intraocular pressures after clear corneal phacoemulsification in open angle glaucoma patients, glaucoma suspects, and normal patients. J Glaucoma. 2006; 15:494-498.
- Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes. J Cataract Refract Surg. 2008;34(5):735-742.
- Poley BJ, Lindstrom RL, Samuelson TW, Schulze R Jr. Intraocular pressure reduction after phacoemulsification with intraocular lens implantation in glaucomatous and nonglaucomatous eyes: evaluation of a causal relationship between the natural lens and open-angle glaucoma. J Cataract Refract Surg. 2009;35(11):1946-1955.
- Mansberger SL, Gordon MO, Jampel H, et al; Ocular Hypertension Treatment Study Group. Reduction in intraocular pressure after cataract extraction: the Ocular Hypertension Treatment Study. Ophthalmology. 2012;119(9):1826-1831.
- Roberts TV, Francis IC, Lertusumitkul S, et al. Primary phacoemulsification for uncontrolled angle-closure glaucoma. J Cataract Refract Surg. 2000;26(7):1012-1016.
- Campbell DG, Vela A. Modern goniosynechialysis for the treatment of synechial angle-closure glaucoma. Ophthalmology. 1984;91(9):1052-1060.
- Tanihara H, Nishiwaki K, Nagata M. Surgical results and complications of goniosynechialysis. Graefes Arch Clin Exp Ophthalmol. 1992;230(4):309-313.
- Lai JS, Tham CC, Chua JK, Lam DS. Efficacy and safety of inferior 180 degrees goniosynechialysis followed by diode laser peripheral iridoplasty in the treatment of chronic angle-closure glaucoma. J Glaucoma. 2000;9(5):388-391.
- Lai JS, Tham CC, Chan JC. The clinical outcomes of cataract extraction by phacoemulsification in eyes with primary angleclosure glaucoma (PACG) and co-existing cataract: a prospective case series. J Glaucoma. 2006;15(1):47-52.
- Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically controlled chronic angle closure glaucoma with cataract. Ophthalmology. 2008;115(12):2167-2173.e2.
- Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology. 2009;116(4):725-31, 731.e1-3.
- Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification vs phacotrabeculectomy in chronic angle-closure glaucoma with cataract: complications. Arch Ophthalmol. 2010;128(3):303-311.
- Ritch R. The treatment of chronic angle-closure glaucoma. Ann Ophthalmol. 1981;13(1):21-23.
- Samuelson TW, Katz LJ, Wells JM, et al. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011;118(3):459-467.
- Francis BA. Trabectome combined with phacoemulsification versus phacoemulsification alone: a prospective, nonrandomized controlled surgical trial. Clinical & Surgical Ophthalmology. 2010;28(10):1-7.
- Gayton JL, Van Der Karr M, Sanders V. Combined cataract and glaucoma surgery: trabeculectomy versus endoscopic laser cycloablation. J Cataract Refract Surg. 1999;25:1214-1219.
- Francis BA, Kwon J, Fellman R, et al. Endoscopic ophthalmic surgery of the anterior segment. Surv Ophthalmol. 2014;59:217- 231.