Sizing Up the Options for Cataract/Glaucoma Surgery
Experts discuss a multitude of recent advances, plus more traditional procedures.
By Jon M. Ruderman, MD, Matthew Lazzara, MD, Carson K. Lam, BS, and Rachel Ruderman
An estimated 20.5 million Americans have cataracts and over 2.22 million Americans are visually impaired from glaucoma. Glaucoma is the second most common cause of irreversible blindness in the United States after AMD. At least four to 10% of the patients in the age group with visually significant cataracts have some form of glaucoma or ocular hypertension.1-7 Many risk factors for cataracts and glaucoma are similar, including age, smoking, use of topical medication, prior trauma, eye surgery and diabetes. In addition, about 38% of patients who have had glaucoma surgery develop cataracts within three years following surgery.8 Clinical decisions on how to handle these combined problems of cataracts and glaucoma, therefore, are inherently complicated.
Prior to phacoemulsification, glaucoma and cataracts were often approached at the same time in a combined fashion, employing intracapsular or extracapsular cataract surgery. Although these procedures were time consuming and incisions were large, most patients did fairly well.9 Subsequent operations, such as repeat trabeculectomy, however, were difficult because of extensive scarring of the conjunctiva. Long-term follow-up data on these patients are generally not available in the ophthalmic literature.
As phaco gained in popularity, our ability to perform small-incision surgery improved. This allowed surgeons to return to the operating room at a later date to perform glaucoma surgery in essentially untouched conjunctiva. Decision making became substantially easier. Most glaucoma patients with cataracts did well with phacoemulsification and intraocular lens implantation alone. Patients who had minimal cataracts and intraocular pressure high enough to cause optic nerve damage could have filtration surgery first and minimally invasive cataract surgery at a later date with less chance of subsequent filtration bleb failure compared to the extracapsular technique.
Newer options for combined procedures have flourished in recent years, although additional studies are required to better comprehend their risk/benefit trade-offs when compared to the traditional approach of trabeculectomy combined with phacoemulsification. Below, we review several options and offer our clinical perspectives on each.
Cataract Surgery Alone
Cataract surgery alone has the advantages of faster visual recovery, improved success rate of future glaucoma procedures, better astigmatism management and easier use of topical or intraocular anesthesia. Certain groups of patients do well with cataract extraction alone. One way to analyze the effectiveness of this option is to divide patients with cataracts and glaucoma into two groups: (1) angle-closure glaucoma patients and (2) those with either open-angle glaucoma or ocular hypertension.
Patients who have angle-closure glaucoma often benefit from cataract surgery alone. Ultrasound biomicroscopy studies and clinical experience demonstrated that shallow anterior chambers often associated with angle closure deepen considerably after cataract surgery.10 While laser iridotomy may relieve the pupillary block component prior to surgery, forward rotation of the ciliary body may still crowd the angle. Additionally, plateau iris may play a larger role than previously considered.11 Lens thickening from age may also narrow the angle.
Cataract surgery (or clear lens extraction in certain cases) alleviates these problems by creating more space in the anterior chamber, opening up the trabecular meshwork, and increasing outflow. Although peripheral anterior synecheia may block outflow after successful cataract surgery in these eyes, goniosynechiolysis using either a special forceps or sodium hyaluronate may help open the angle and increase outflow and lower the intraocular pressure after surgery.12 Trabeculectomy in angle-closure patients, on the other hand, may be associated with a higher incidence of postoperative shallow chambers and malignant glaucoma. Therefore, cataract surgery alone is indicated in most patients with combined angle-closure glaucoma and cataracts.
Additionally, in patients with visually significant cataracts and well-controlled open-angle glaucoma, as well as in those with ocular hypertension, cataract surgery alone is often sufficient. Cataract surgery lowers IOP by 1-3 mm Hg on average. Recently, Poley et al.13 demonstrated that the higher the preoperative pressure the greater the drop in pressure after cataract surgery. While some of the results may occur from a regression to the mean, this phenomenon has been noted by many other authors.14-16
Poley retrospectively reviewed cataract surgery in 588 eyes with a range of presurgical IOP from 9.8 to 31 mm Hg, with follow-up from one to 10 years, with an average of 4.5 years. The group with the highest IOP (23-31) had a 27% reduction in pressure at the end of the study. Those with a pressure of 15-17 had a smaller reduction (−1.6 mm Hg, or 10%). In glaucoma eyes alone (n=17, IOP 23-29) with an average of 5.8 years of follow-up, the average IOP went down 8.4 mm Hg, or 34%. It has been noted elsewhere that eyes with pseudoexfoliation (PXF) may also have a greater than average drop in IOP following phacoemulsification and IOL implantation.17
Lens extraction in eyes with absent or minimal cataract should not be advocated as a method to lower IOP except in some patients with angle-closure glaucoma. Clinicians must evaluate every patient individually and decide whether the IOP has exceeded the “target” level needed to prevent nerve damage. Intolerance to medication (due to allergy, toxicity, cost or non-compliance) is a factor that must be considered and may make a patient a better candidate for combined surgery or filtration surgery alone.
Glaucoma Filtration Surgery First
Filtration surgery prior to cataract extraction at a later date is indicated when a patient presents with elevated intraocular pressures, optic nerve damage and minimal cataract formation. If the IOP is very high (in the 30 mm Hg range and above) and there is considerable nerve and visual field damage, but not significant lens opacity, filtration alone should be performed first. Another factor that might lead to filtration surgery alone is the refractive error of the eye. If cataract surgery would leave the patient anisometropic, it is prudent to perform filtering surgery alone even in the face of a significant cataract.
Talking to the patient is essential, as many patients fear a second procedure and would like to have combined surgery while others prefer the simplest procedure possible even if it requires returning to the operating room to remove the cataract at a later date. Most filters lose 1-4 mm Hg after subsequent cataract surgery and thus a combined procedure in normal-tension glaucoma may be preferable as this can be followed up with a second filter in the future if the need arises.
Combined Glaucoma and Cataract Surgery
Combined cataract and glaucoma surgery is less common now than it was five to 10 years ago. Improved glaucoma medications as well as small-incision cataract surgery permit essentially “primary” glaucoma surgery after cataract extraction. The preference for combined surgery varies with the skill and opinion of the surgeon. Our indications for combined surgery include the following: a visually significant cataract and high IOP with moderate visual field loss, borderline IOP with severe visual field loss, or well-controlled IOP with visual field at or approaching fixation. In addition, if the patient's use of medication is unreliable for whatever reason (allergies, compliance, cost, etc.) or if the patient does not want two separate procedures, then combined surgery becomes our preferred procedure.
We prefer separating the cataract and trabeculectomy sites. Ophthalmic literature suggests two-site surgery has some advantages in terms of less medication being needed after surgery. Use of antimetabolites also appears somewhat helpful, though not overwhelmingly so.18,19 Variations in techniques provide minimally different results and should be tailored to the experience and skill of the surgeon.20,21
New Modalities of Combined Surgery
Recently, a number of new techniques have been developed for both glaucoma surgery alone and for combined surgery (discussed below). Some of these procedures are less complex than traditional phaco-trabeculectomy procedures, but none have been formally proven to reduce complication rates and improve IOP outcome. Most do not produce filtration blebs, which may leave patients more comfortable and less prone to subsequent infection. Many of these procedures increase the cost to patients and insurance companies without proven benefit. Nevertheless, it is probable that over the next few years effectiveness of one or more of these procedures will increase the popularity of combined surgery.
• Phaco ECP. This procedure adds endoscopic cyclo-photocoagulation at the time of cataract surgery, using a 30-degree curved microendoscope (Endo Optiks) that provides endothelial photocoagulation of up to 300 degrees of the ciliary processes through a single incision. Success corresponds to treatment of both the anterior and posterior portions of the ciliary body. This causes tissue whitening and shrinkage but does not harm the core of the ciliary body, resulting in reduced inflammation and postoperative pain.
Theoretical advantages of ECP include: (1) a relatively easy learning curve for experienced phaco surgeons, (2) precise localization of target tissues, (3) titratable and repeatable application, and (4) potentially low risk compared with conventional surgery. Limitations of this procedure include: (1) limited efficacy when compared to filtration surgery in lowering IOP,22 (2) increased incidence of cystoid macular edema,23 (3) inflammation, (4) pain, (5) hypotony and (6) rarely phthisis.
Few independent studies have looked at the long term effectiveness of ECP. A multicenter study supported by Endo Optiks comparing combined ECP with phacoemulsification alone showed a 2.2 mm Hg vs. 0.9 mm Hg IOP reduction in favor of the combined procedure at a mean of 31.2 months.24 A greater reduction in postoperative medications (1.51 to 0.03) was noted. There are no studies evaluating the value of the procedure when used in different types of glaucoma. There are few studies comparing techniques or treatment parameters.
A possible approach to ECP (Steven Vold, MD, personal communication) may be to start with a mild treatment in a patient with marginal control of mild glaucoma who has difficulty tolerating glaucoma medication. One should not use ECP in patients who need filtration surgery as the primary way to control IOP, and do not use in uveitis or pseudoexfoliation patients.
Newer options include (clockwise from upper left) the Express mini-shunt, canaloplasty, the iStent and the Trabectome. COURTESY OF ALCON; BRIAN FRANCIS, MD; GLAUKOS
• Phaco Trabectome. This surgery has the advantage of preserving conjunctiva by performing an ab interno trabeculotomy using electrocautery of the trabecular meshwork followed by aspiration of trabecular debris, using a minimally-invasive surgical system called the Trabectome (NeoMedix). A protective footplate prevents damage to the posterior wall of Schlemm's canal and the collector channels while incising the juxtacanalicular trabecular meshwork. Irrigation allows posterior displacement of the lens/iris diaphragm and increases visualization and access to the angle. Francis et al., in a large non-comparative study of 304 consecutive patients, demonstrated a significant lowering of the IOP in combined Trabecutome-cataract patients. It was unclear from the data whether the lowering of pressure was from the cataract surgery alone or from the Trabectome procedure.25
A recent study of phaco-Trabectome combined procedures by Minkler et al. with follow-up in 45 cases showed a decrease in IOP from 20 mm Hg to about 16 mm Hg over 12 months.26 Medication use decreased from 2.63 preoperatively to 1.5 during the same follow-up period. Complication rates have generally been found to be low, with the most common being blood reflux from Schlemm's canal during the procedure. IOP spikes greater than 10 mm Hg on the first postoperative day occurred, as well as some instances of blood clotting and late blood reflux. While having been shown to have some IOP-lowering effect without the risks of traditional glaucoma surgery, ultimate IOP levels seem to be limited to the mid-teens with this device.
• iStent and Phaco. A novel trabecular bypass device called iStent (Glaukos) has been shown to reduce IOP and the number of postop glaucoma meds required for IOP control. The shunt, which appears like a small snorkel, is placed ab interno into the trabecular meshwork through a paracentesis-like incision.
Fea reviewed 36 patients with a baseline IOP of 17.9 mm Hg for the combined group and 17.3 mm Hg for the phaco group.27 At 15 months after surgery, the combined iStent phaco group IOP was 16.6 vs. 19.2 for the straight phaco group. Medicine use was marginally less in the combined group.
Samuelson et al. randomized 240 eyes of patients with mild to moderate open-angle glaucoma to either combination surgery with a single iStent or cataract surgery alone. The percentage of patients maintaining an IOP less than or equal to 21 mm Hg without medication was 72% in the combined group versus 50% in the control group at one year.28 It has been proposed that multiple iStents (two or three) placed at intervals in the trabecular meshwork might improve results. Newer versions of the iStent are designed to make multiple implantations possible through the same entryway, which may improve efficacy without additional risk.
Advantages of this surgery are that it is fast, preserves conjunctiva and is relatively complication free. Disadvantages are that it requires some trabecular surgery experience and that its cost may be significant if multiple stents are required for meaningful IOP reduction.
• Express Shunt Phaco. The Express shunt (Alcon) is a stainless steel tube that allows filtration from the anterior chamber to the subconjunctival space in a similar fashion as a sclerotomy. Kanner and Netland reviewed 345 eyes when an Express shunt was used alone and 114 eyes when combined with phacoemulsification.29 Eyes were followed for one to 46 months in both groups. At three years the “success” rate was 94.8% in the Express alone and 96% in the combined. There was, however, higher IOP and more medications required reported in the combined group. Tube obstruction and hypotony were the most common complications and were similar in both groups.
Currently, Express shunt combined with phacoemulsification is our most frequent procedure performed when combined surgery is indicated and a low IOP is needed. Experience has demonstrated a need to close the scleral flaps more tightly than a typical trabeculectomy flap in order to prevent hypotony. The flap and incision for the Express are prepared prior to phaco and the device is inserted following removal of the cataract and insertion of the IOL.
Advantages of this procedure are a more stable anterior chamber with a lessened risk of hypotony, and a quicker recovery without the need for a peripheral iridotomy when compared to traditional trabeculectomy. Disadvantages include those associated with filtering procedures with long-term bleb management and complications, as well as device-related complications such as exposure and migration. An additional cost over trabeculectomy is also incurred.
• Canaloplasty. Circumferential viscodilation and tensioning of Schlemm's canal using a microcatheter (iScience) and suture is a procedure known as canaloplasty. In this procedure, a fornix-based flap is fashioned. A 4-mm by 4-mm scleral flap of about one-third scleral thickness is made. A deeper flap is created within the superficial flap at about 90% depth. The posterior edge of Schlemm's canal is identified and a lighted endoscopic fiber is threaded through the canal. A suture is tied to the probe when it reappears. The suture is drawn backwards, through the canal and tied onto itself to create tension in the canal. It is thought that this tension improves outflow through the canal and subsequently lowers IOP. Lewis et al. found an average IOP reduction over three years from 23.5 to 13.6 mm Hg in 30 eyes having undergone combined procedure with this technique. Medication use also was reduced and minimal complications were encountered, however no control cohort was used in this pilot study.30
An advantage of the procedure is that no significant bleb is usually formed. Conversely, the technique can be difficult to master, and a large area of the conjunctiva needs to be dissected, making future filtration surgery difficult. The final resulting intraocular pressure may be slightly lower than other forms of trabecular surgery.
• Phaco and Tube Shunt Surgery. Generally, these procedures are reserved for patients who have failed conventional filtration surgery and present with intractable glaucoma, some prior glaucoma surgery and cataracts. This can be challenging surgery with high failure and complication rates. There is little in the literature that compares this form of combined surgery with others. A retrospective review of 36 combined cases using both Ahmed and Baerveldt tube shunts was published by Chung et al. in 2004.31 The study population was patients of Asian origin with refractory glaucoma. The mean IOP was reduced from 28.0 to 15.2 mm Hg with a mean follow-up of 13 months. Glaucoma medication use dropped on average from 2.4 to 0.3 at last follow up. Postoperative complications occurred in 12 (36%) patients, with hypotony in six eyes (19%).
Some specialists recommend placing the tube through the ciliary sulcus in these patients once the crystalline lens has been removed, mediating some of the risk of corneal decompensation.32 The success of this approach has not been adequately delimited, but it probably has a higher failure rate secondary to tube obstruction.
Conclusion
We are in a rapidly evolving era that has seen a shift from combined cataract surgery to mostly cataract surgery alone followed by glaucoma surgery if needed. With new technologies, the indication for combined surgery may expand dramatically if the new procedures can be performed in a timely and cost-effective manner. Preservation of conjunctiva, faster visual rehabilitation and absence of the filtering bleb seem to be significant improvements.
Every patient presents with a unique constellation of clinical findings, including disease severity, initial IOP, type of glaucoma and ability to tolerate medication. No definitive guidelines exist currently regarding the superiority of one procedure over another.
We believe that cataract surgery alone is indicated in the majority of cases of angle-closure glaucoma, and in those cataract patients with ocular hypertension and mild glaucoma controlled adequately by medication. Combined surgery, when indicated, should be performed with the individual surgeon's best and most comfortable technique. The verdict is still not in as to how the new treatment modalities will change our decision process. Long-term, well-controlled studies are needed to answer those questions. OM
This work was supported by a grant from the Chicago Center for Vision Research.
| Premium Lenses and Cataract/Glaucoma Surgery |
|---|
| Recently there has been excitement regarding the use of presbyopic lenses (Crystalens, Tecnis, Restor) for cataract surgery. Diffractive lenses such as the Restor or the Tecnis are less likely to succeed in patients with glaucoma or “pre-perimetric” glaucoma, as splitting the light may aggravate visual field defects. These lenses are effective in patients with moderate hyperopia and narrow or closed angles, who do not have visual field loss and where nerves appear healthy. We perform OCT nerve fiber layer measurements on all such patients in order to avoid use of diffractive lenses in patients with significant nerve fiber layer defects. Although the optics of accommodative IOLs (Crystalens) will not adversely affect patients with concomitant glaucoma, they should not be used in cases of significant PXF or trauma because of potential zonular instability. Eyes with significant visual field defects may obtain a poor visual result, irritating a premium IOL patient who has gone to considerable expense for the “best” visual outcome. Toric lenses are valuable in patients with glaucoma and cataracts, but may shift position when used in combined surgery because of potential anterior chamber shallowing following filtration. Patients with pseudoexfoliation or prior trauma may also show greater variation in lens position, especially if zonular support of the capsular bag has been disrupted. |
| Getting Started in Combined Phaco/Glaucoma Procedures: A Q&A With Steven Silverstein, MD, FACS |
|---|
| Q. Do you believe it is important that caract surgeons Should be proficient in performing combined phaco/glaucoma surgery? If so, why? A. Previously, most combined procedures, typically referring to phaco/trabeculectomy, have been done primarily by fellowship-trained glaucoma specialists, though the completion of residency training does generally require proficiency in performing each. Many higher-volume cataract surgeons have become comfortable with the newer trabeculectomy techniques, including clear corneal temporal cataract surgery/superior Mitomycin C trabeculectomy, employing either standard removal of a block of trabecular meshwork or the Express mini-shunt (Alcon). However, most comprehensive anterior segment ophthalmologists still reserve tube shunt surgery for glaucoma specialists, in part because it can be a technically more difficult surgery to perform, but ironically often requires less immediate postoperative follow up than a trabeculectomy, due to the higher incidence of hypotony or the requirement of 5FU injections with the latter. The comprehensive ophthalmologist, therefore, will offer combined procedures that include trabeculectomy or tube shunts based upon either their exposure to and comfort level with this surgery during training, or the desire to attend wet lab-assisted courses post training, in order to include this in their surgical armamentarium. Additionally, the distance a patient must travel, especially in more rural communities, to see a glaucoma specialist may play a role in the surgical services an anterior segment surgeon wishes to provide. Q.What are the advantages of performing a combined procedure in certain cataract surgery patients? Any disadvantages? A. Advantage for combined procedures include less exposesure to the risk of anesthesia, especially in the case of a peri- or retrobulbar block, less risk of endophthalmitis due to multiple procedures, less cost for the patient in terms of additional perioperative medications to purchase, potentially faster improvement of intraocular pressure than if the cataract surgery is performed first, waiting to do the trabeculectomy at a later date, or, failure of the trab if the cataract is performed in a different setting. In addition, there is potentially less risk of trauma to the corneal endothelium in one procedure rather than two full surgeries, and the healthcare cost is also reduced to the insurance companies or Medicare/Medicaid (which theoretically, could be passed on to the pool of insured patients or the taxpayers). Postop visits are reduced, thereby saving staff and physician time during the bundled post opperiod. The risk of CME and other sequelae of inflammation is decreased by exposing the eye to fewer procedures, and ultimately, it is less stressful to the patient to experience one surgery rather than two. Disadvantages potentially include the unlikely but potential risk of wound leak from a separate cataract incision, making control of postoperative IOP following a combined procedure more difficult. Also, a minority of patients can potentially enjoy enough of a pressure-lowering response from cataract surgery alone that trabeculectomy might not be necessary, especially since many trabs and some tube shunts ultimately fail after a period of time, usually due to scarring and inflammation, so a primary glaucoma procedure might have been saved for a later date. Lastly, physicians and ASCs are not reimbursed at the same rate for doing a combined procedure as when having broken the surgeries into two separate events, despite the fact that the complexity of the surgeries is no different, nor is the postoperative care. The reimbursement for the surgeon is 100% for the primary procedure and 50% for all other procedures performed during the same surgical experience. Q. For cataract surgeons who are not experienced in performing combined procedures, what would be the safest and best way to start? A. Contracting the Glaucoma Society and the Academy of Ophthalmology/ASCRS will be the best sources for certified courses given post-training, which are often held during national meetings. Alternatively, periodic standalone courses are announced in the ophthalmic magazines. If a physician lives in a city with an academic training center, working alongside a glaucoma specialist, possibly with supervision of the surgeon's first few cases, may provide an opportunity for certification, though formal documentation is not typically mandatory except by certain medical malpractice insurance carriers and surgery centers/hospital ORs. Q. There are several new blebless glaucoma surgeries that have been recently introduced or are awaiting FDA pproval. They have been successfully used in combined phaco/glaucoma procedures. What kind of place do you see for these types of surgeries in the future? A. This is the opportunity most fitting for all anterior segment comprehensive ophthalmologists, as they already possess the skills necessary to perform most of these procedures, and if interested, can attend brief symposia with wet labs and in-surgery observation for those procedures requiring some additional training. Currently, ECP (endocyclophotocoagulation), Trabectome, and canaloplasty are the most common approved blebless glaucoma procedures performed either as standalone procedures or in conjunction with cataract surgery. The latter two procedures are more complex, and would therefore require more extensive training and proctoring. ECP would require minimal training, but is associated with a significant equipment cost if the preferred facility does not own this technology. Two interesting blebless glaucoma surgical technologies under study in the United States are the Glaukos iStent and the Transcend CyPass device. The Glaukos iStent is placed under goinioscopic viewing in the trabecular meshwork directly into Schlemm's canal at the end of cataract surgery. The current phase of the study is looking at the benefits of placing more than one stent several clock hours apart. The Transcend device is also implanted under gonioscopic guidance into the suprachoroidal space. At this time, involvement with these two technologies requires participation in the FDA trials. I have very much enjoyed working with the Glaukos iStent thus far in both phases of the study, and find the novel delivery system easy to use once the surgeon becomes comfortable working in the angle via gonioscopy similar to learning ALT/SLT. Q. In patients with very high IOP and cataract, what types of combined procedure could be effective? A. The blebless ab interno procedures in existence today, or under development, are not able to achieve the significant pressure-lowering targets many moderate to severe glaucomatous eyes demand. Though there are several mechanisms of action that contribute to glaucomatous optic neuropathy, sometimes requiring special surgical procedures beyond those most commonly used for POAG or low-tension glaucoma (i.e., mixed mechanism, angle closure, traumatic, inflammatory), in general, trabeculectomy with Mitomycin-C, 5FU or sometimes both or tube shunts are the preferred surgical procedures performed, either alone or in conjunction with cataract surgery. If neovascular glaucoma due to ocular occlusive disease or other causes is present, retinal laser and cyclo-destructive procedures may be necessary as well. Though beyond the scope of this discussion, some patients who fail primary trabeculectomy will ultimately require either a second trabeculectomy or a tube shunt if the addition of pressure-lowering medicines is unsuccessful in controlling further optic nerve damage and field loss. Q. Opthalmology residents have traditionally been taught to perform trabeculectomy and, to a lesser extent, shunts. Would you advocate expanding training in glaucoma surgeries to some of the newer procedures? A. Definitely. These adjunctive technologies emerging onto the.marketplace will likely obviate the need for more aggressive surgeries in some patients, or at a minimum, delay the need for them, providing a faster postoperative recovery or a stronger likelihood of trab or tube survival if necessary later in a patient's life (considering the accepted rate of failure of these procedures over time). Also, for many patients living either at great distance from a glaucoma specialist or for whom transportation back and forth for multiple follow-ups is difficult, these more controlled and consistent procedures require little more care than in routine cataract surgery patients. Q. As an ophthalmologist with extensive experience in performing all types of combined procedures, do you have any other thoughts that would be of interest to cataract surgeons? A. Whether you have been in practice for many years or newly trained, become familiar and comfortable with one or two of these ancillary blebless technologies as they become available. You will find that there is a minimal learning curve, and the companies will be eager to come to your hospital OR or ASC to proctor your technique, and to share the experiences derived during the FDA clinical studies. Steven M. Silverstein, MD, FACS, is a regular contributor to Ophthalmology Management and often lectures on ophthalmic topics. He is the owner of Silverstein Eye Centers, based in Kansas City, Mo. In addition to his private practice, Dr. Silverstein serves as an assistant professor of ophthalmology at the University of Missouri Kansas City Medical School, and clinical professor of ophthalmology at Kansas City University of Medicine and Biosciences. Dr. Silverstein can be reached at ssilverstein@silversteineyecenters.com. |
References
1. Friedman DS, Wolfs RC, O'Colmain BJ, et al. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. Apr 2004; 122(4):532-538.
2. Congdon N, Vingerling JR, Klein BE, et al. Prevalence of cataract and pseudophakia/aphakia among adults in the United States. Arch Ophthalmol. Apr 2004;122(4):487-494.
3. Tielsch JM, Sommer A, Katz J, Royall RM, Quigley HA, Javitt J. Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey. JAMA. Jul 1991;266(3):369-374.
4. Dielemans I, Vingerling JR, Wolfs RC, Hofman A, et al. The prevalence of primary open-angle glaucoma in a population-based study in The Netherlands. The Rotterdam Study. Ophthalmology. Nov 1994;101(11):1851-1855.
5. Klein BE, Klein R, Sponsel WE, et al. Prevalence of glaucoma. The Beaver Dam Eye Study. Ophthalmology. Oct 1992;99(10):1499-1504.
6. Kreuger DE, Milton RC, Maunder LR. The Framingham eye study: introduction to the monograph. Surv Ophthalmol. 1980 May-Jun 1980;24(6):614-620.
7. Leske MC, Wu SY, Nemesure B, Hennis A, Group BES. Causes of visual loss and their risk factors: an incidence summary from the Barbados Eye Studies. Rev Panam Salud Publica. Apr 2010;27(4):259-267.
8. Lichter PR, Musch DC, Gillespie BW, et al. Interim clinical outcomes in the Collaborative Initial Glaucoma Treatment Study comparing initial treatment randomized to medications or surgery. Ophthalmology. Nov 2001;108(11):1943-1953.
9. Newton FH. A combined operation for cataract and glaucoma. A simple, adaptable, two-stage procedure for one operation. Am J Ophthalmol. Nov 1965;60(5):918-919.
10. Shin HC, Subrayan V, Tajunisah I. Changes in anterior chamber depth and intraocular pressure after phacoemulsification in eyes with occludable angles. J Cataract Refract Surg. Aug 2010;36(8):1289-1295.
11. Mochizuki H, Takenaka J, Sugimoto Y, Takamatsu M, Kiuchi Y. Comparison of the Prevalence of Plateau Iris Configurations Between Angle-closure Glaucoma and Open-angle Glaucoma Using Ultrasound Biomicroscopy. J Glaucoma. 2011 Jun-Jul 2011;20(5):315-318.
12. Mirshahi A, Scharioth GB. Nonpenetrating glaucoma surgery with goniosynechiolysis ab interno: a surgical technique. Eur J Ophthalmol. 2009 Jan-Feb 2009; 19(1):147-150.
13. Poley BJ, Lindstrom RL, Samuelson TW, Schulze R. 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. Nov 2009;35(11):1946-1955.
14. Suzuki R, Tanaka K, Sagara T, Fujiwara N. Reduction of intraocular pressure after phacoemulsification and aspiration with intraocular lens implantation. Ophthalmologica. 1994;208(5):254-258.
15. Shingleton BJ, Rosenberg RB, Teixeira R, O'Donoghue MW. Evaluation of intraocular pressure in the immediate postoperative period after phacoemulsification. J Cataract Refract Surg. Nov 2007;33(11):1953-1957.
16. Issa SA, Pacheco J, Mahmood U, Nolan J, Beatty S. A novel index for predicting intraocular pressure reduction following cataract surgery. Br J Ophthalmol. May 2005;89(5):543-546.
17. Shingleton BJ, Laul A, Nagao K, et al. Effect of phacoemulsification on intraocular pressure in eyes with pseudoexfoliation: single-surgeon series. J Cataract Refract Surg. Nov 2008;34(11):1834-1841.
18. Wong PC, Ruderman JM, Krupin T, et al. 5-Fluorouracil after primary combined filtration surgery. Am J Ophthalmol. Feb 1994;117(2):149-154.
19. Ruderman JM, Fundingsland B, Meyer MA. Combined phacoemulsification and trabeculectomy with mitomycin-C. J Cataract Refract Surg. Oct 1996;22(8):1085-1090.
20. Gdih GA, Yuen D, Yan P, Sheng L, Jin YP, Buys YM. Meta-analysis of 1- versus 2-Site Phacotrabeculectomy. Ophthalmology. Jan 2011;118(1):71-76.
21. Wyse T, Meyer M, Ruderman JM, et al. Combined trabeculectomy and phacoemulsification: a one-site vs a two-site approach. Am J Ophthalmol. Mar 1998;125(3):334-339.
22. Gayton JL, Van Der Karr M, Sanders V. Combined cataract and glaucoma surgery: trabeculectomy versus endoscopic laser cycloablation. J Cataract Refract Surg. Sep 1999;25(9):1214-1219.
23. Chen J, Cohn RA, Lin SC, Cortes AE, Alvarado JA. Endoscopic photocoagulation of the ciliary body for treatment of refractory glaucomas. Am J Ophthalmol. Dec 1997;124(6):787-796.
24. Berke SJ. Phacoemulsification combined with endoscopic cyclophotocoagulation in the management of cataract and medically controlled glaucoma:a large,long term study.Paper Presented at:American Glaucoma Society 16th Annual Meeting;March 4,2006;Charleston,SC.
25. Francis BA, Minckler D, Dustin L, et al. Combined cataract extraction and trabeculotomy by the internal approach for coexisting cataract and open-angle glaucoma: initial results. J Cataract Refract Surg. Jul 2008;34(7):1096-1103. 26. Minckler D, Mosaed S, Dustin L, Ms BF, Group TS. Trabectome (trabeculectomy-internal approach): additional experience and extended follow-up. Trans Am Ophthalmol Soc. 2008;106:149-159; discussion 159-160.
27. Fea AM. Phacoemulsification versus phacoemulsification with micro-bypass stent implantation in primary open-angle glaucoma: randomized double-masked clinical trial. J Cataract Refract Surg. Mar 2010;36(3):407-412.
28. Samuelson TW, Katz LJ, Wells JM, Duh YJ, Giamporcaro JE, Group UiS. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. Mar 2011;118(3):459-467.
29. Kanner EM, Netland PA, Sarkisian SR, Du H. Ex-PRESS miniature glaucoma device implanted under a scleral flap alone or combined with phacoemulsification cataract surgery. J Glaucoma. Aug 2009;18(6):488-491.
30. Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg. Apr 2011;37(4):682-690.
31. Chung AN, Aung T, Wang JC, Chew PT. Surgical outcomes of combined phacoemulsification and glaucoma drainage implant surgery for Asian patients with refractory glaucoma with cataract. Am J Ophthalmol. Feb 2004;137(2):294-300.
32. Weiner A, Cohn AD, Balasubramaniam M, Weiner AJ. Glaucoma tube shunt implantation through the ciliary sulcus in pseudophakic eyes with high risk of corneal decompensation. J Glaucoma. Aug 2010;19(6):405-411.
| Jon M. Ruderman, MD, is an associate professor of ophthalmology at the Feinberg School of Medicine at Northwestern University in Chicago and Co-director of the Glaucoma Fellowship program. He can be reached at j-ruderman@northwestern.edu. Matthew Lazzara, MD, completed his ophthalmology residency at Tufts and is now a glaucoma fellow with the University Eye Associates/Northwestern University training program. Carson Lam is a fourth year medical student at Feinberg and former engineering student at Northwestern going into ophthalmology. Rachel Ruderman is at the University of Michigan in the International Studies Program, concentrating in Global Health and Environment. |
![]({"src":"/media/vffbrgdy/82011.jpg","focalPoint":null,"crops":[{"alias":"thumbnail","width":1110,"height":700,"coordinates":null}]})