Techniques for Combined Cataract and Glaucoma Surgery
Cataract and glaucoma are the leading causes of blindness worldwide. The prevalence of both diseases is increasing with aging population. Techniques for cataract surgery have undergone significant refinements with excellent visual outcomes enjoyed by our patients. The goal of glaucoma surgery is to lower intraocular pressure to prevent or slow down the progression of optic nerve damage and associated visual field loss. Although many patients present with these concomitant diseases, there is no general consensus on surgical management of coexisting cataract in patients with glaucoma. The surgeon has to decide which approach may be best suited for a particular patient, combined surgery or staged (sequential) surgeries, depending on the patient’s severity of glaucoma and visual compromise from a cataract. This brief review will discuss indications, surgical techniques, and outcomes of various types of combined cataract and glaucoma surgery.
Combined Cataract and Glaucoma Surgery
- Patient Convenience: A single visit to the operating room maybe beneficial in terms of cost, risks of anesthesia, presence of other medical conditions precluding additional stress of multiple surgeries, and social issues
- Avoid potential post-operative IOP spike which can be seen after cataract surgery, especially for cases with advanced optic neuropathy
- Long term control of IOP with glaucoma surgery and quick visual recovery from removal of a significant cataract
- More intraoperative and postoperative complications than with either cataract surgery or glaucoma surgery alone. Cataract surgery in patients with glaucoma may prove to be more challenging due to chronic miosis/poor pupil dilation from medications or presence of synechiae. Patients with glaucoma secondary to trauma or exfoliation syndrome may have weak/fragile zonules, which may lead to zonular dehiscence and vitreous loss. Vitreous loss may lead to failure of glaucoma surgery. More inflammation is induced with combined cases, especially with one site surgery.
- Combined procedures may be less effective than glaucoma surgery alone in controlling IOP, especially for eyes with advanced glaucomatous damage
- Longer visual recovery
Regardless of the approach, a thorough discussion with the patients regarding the potential risks, benefits, and alternatives should be done.
When to Consider Combined Surgery
Combined cataract extraction and glaucoma surgery (trabeculectomy, glaucoma drainage implant surgery, or any of the newer surgical approaches for glaucoma) should be carefully selected and individualized depending on clinical findings in each case:
- Cataract surgery alone is sufficient for patients with well controlled IOP in the setting of early to moderate optic nerve damage.
- Patients with uncontrolled IOP in the presence of severe optic nerve damage should receive glaucoma surgery first, followed by cataract extraction a few months later
- Combined surgery may be best suited for a patient with a visually signifiant cataract with uncontrolled glaucoma despite maximal medical therapy and/or laser trabeculoplasty. Cost is often an issue for many patients and eliminating medications can help reduce the financial burden. Poor compliance with glaucoma medications can also be an issue to consider both procedures together.
Patients with both cataract and glaucoma should undergo a complete ocular examination to determine the extent of each disease that is contributing to visual deterioration. This is accomplished by careful history and clinical exam includings:
- Glaucoma Medications--How many medications is the patient on? Are there serious side effects of these medications affecting other medical issues?Is compliance an issue? Is cost an issue?
- Visual acuity—What is the patients best corrected visual acuity? What is the best potential visual acuity? Is glare an issue? How much of decline in vision is due to cataract versus glaucoma?
- Intraocular pressure—Is the IOP controlled?
- Gonioscopy - Is the angle open or closed? May require special post-operative management in cases of CACG eyes which are at increased risk for malignant glaucoma. Is there subtle angle recession?
- Slit Lamp Exam-Evaluate type and extent of cataract. Is there evidence of prior trauma with iridodenesis or phacodenesis? pseudoexfoliation, or posterior synechiae? How is pupil dilation?
- Optic nerve exam and retina evaluation- How damaged is the optic nerve? Is there evidence of coexisting macular or retinal pathology that may be playing a role in decline of visual acuity and may also limit visual potential?
- Visual Field Testing—Aids in evaluation of extent of glaucoma. If a patient has central island from severe glaucoma, cataract surgery may not be beneficial in terms of visual outcome.
After careful evaluation and discussion with the patient, the decision regarding single procedure (cataract or glaucoma surgery alone) or combined surgery (combined cataract and glaucoma surgery) can be made.
Poor pupillary dilation is often seen in patients with glaucoma. This can be a result of chronic use of miotics, chronic inflammation leading to synechiae formation, chronic angle closure, prior trauma, or prior laser procedures. Patients with pseudoexfoliation, diabetes, or those on alpha-adrenergic receptor blockers may also have issues with dilation. Proper identification of these conditions prior to surgery can help plan the necessary steps that need to be taken before and during the procedure to ensure success of the case.
If the patient is on any miotics, these should be stopped before cataract surgery. The use of intracameral preservative-free epinephrine 1:10,000 may aid in pupillary dilation. Synechiae and pupillary membranes may often be broken using a cyclodialysis spatula. Once these adhesions are broken, the viscoelastic can help in further dilation. If these measures are not sufficient any of the following steps may be used:
• Pupil Stretching using Kuglen or Sinsky
• Mechanical dilation using iris hooks, Morcher dilating ring, or Malyugan ring
Inadequate Anterior Capsule Visualization
Inadequate anterior capsule visualization may occur in patients with corneal opacities or edema and when there is a poor red reflex as in patients with dense cataracts or in the presence of vitreous hemorrhage. In such cases the use of trypan blue can greatly aid in safely completing the capsulorhexis.
Cataract surgery is now frequently performed under topical anesthesia using 2% Xylocaine jelly. Trabeculectomies are now also being performed under topical anesthesia with supplemental intracameral or subtenon injections with lidocaine or marcaine. Combined cases tend to be lengthy and can be performed using retrobulbar, peribulbar, or topical anesthesia depending on the surgeons experience and preference.
Single-Site vs. Two-Site Surgery (Cataract Extraction with Trabeculectomy)
Once the decision to do combined surgery has been made, it is up to the surgeon to decide whether to perform a single-site or a two-site surgery. Single-site surgery is done using the scleral tunnel technique. With the increasing popularity of temporal clear cornea approach for cataract surgery, two-site surgery has gained more popularity.
Single-Site Surgery Technique
Single-Site Surgery is done with the surgeon sitting superiorly. Both the trabeculectomy and cataract surgery are performed using the same conjunctival and scleral incisions.
1. Superior peritomy is performed to expose bare sclera. Gentle cautery is performed as needed. Paracentesis is made either before or after the peritomy.
2. If using anti-metabolites, such as 5-flourouracil (5-FU) or mitomycin-C (MMC), these may be applied using the surgeon's preferred technique.
3. A partial-thickness scleral flap, hinged at the limbus is made. Alernatively, a scleral tunnel incision can be made initially, with completion of the flap after the cataract portion of the surgery using Vanass scissors
4. A keratome is used to enter the anterior chamber
5. Phacoemulsification is performed in the usual manner
6. Intraocular lens is inserted
7. Viscoelastic is removed
8. Sclerectomy is performed using a Kelley descsment’s punch or wedge sclerectomy using a sharp point blade and Vanass scissors
9. A peripheral iridectomy may be made if desired.
10. The scleral flap is closed using interrupted or releasable 10-0 mylon sutures. These should be adjusted to ensure adequate flow.
11. Tenons and conjunctiva are closed.
Advantages of Single-Site Surgery
1. Saves Time
a. One wound is made
b. There is no need for the surgeon to change his/her position and
Disadvantages of Single-Site Surgery
1. More post-operative inflammation
a. Excessive conjunctival manipulation may
influence the outcome of filtration surgery
b. Longer visual recovery
2. Care needed to avoid spillage of antimetabolites into the anterior
chamber, if used after creation of a scleral flap
Two-Site Surgery Technique
In two-site surgery, the surgeon first completes the cataract extraction sitting temporally and then moves superiorly to complete the trabeculectomy.
1. Temporal clear corneal cataract surgery is performed in the usual manner. It is recommended that the main incision be sutured (typically using 10-0 nylon) to prevent wound leak.
2. Surgeon moves superiorly and performs trabeculectomy using his or her preferred technique.
IOP Control with Single vs. Two-Site Surgery
1. Both approaches have been shown to be effective in lowering
2. Two-site surgery may have better post-operative IOP control
and less need for adjunctive glaucoma medications
Post-operative management for combined cases is similar to that for glaucoma surgery. The patient should be seen on the first post-operative day and then weekly thereafter until the IOP has stabilized. Sutures may by pulled or lysed as needed. In the presence of significant inflammation, more frequent visits may be required.
- Antibiotic drops every four hours for the first week.
- Steroid drops every 2 hours for the first month, followed by taper. Steroids may be tapered sooner following tube shunt surgery or if a concern is raised about steroid response.
- Cycloplegics may be used in cases of shallow anterior chamber or hypotony. Also beneficial in post-operative cases of CACG to prevent malignant glaucoma.
Similar to the ones encountered with cataract surgery alone or trabeculectomy alone. The following list includes some of the complications encountered after glaucoma surgery. For additional information, refer to the section on Trabeculectomy.
- shallow or flat anterior chamber
- persistent inflammation
- choroidal effusion
- bleb leaks
- filtration failure
- corneal dellen
- suprachoroidal hemorrhage
- chronic hypotony
The risk of persistent hypotony and associated complications such as maculopathy, late-onset bleb leaks, infection of the bleb, and endophthalmitis may be increased with the adjunctive use of antifibrotic agents. For additional information, refer to the section on Trabeculecomy.
Other Types of Combined Surgery
Traditional combined cataract and glaucoma surgery has involved trabeculectomy. Other forms of glaucoma surgery have been increasingly combined with cataract surgery. These include:
- Glaucoma drainage devices
Glaucoma drainage devices are generally reserved for complicated secondary glaucomas, such as uveitic glaucoma and neovascular glaucoma, young patients, eyes with previously failed filters, and in eyes with insufficient conjunctiva due to scarring from prior surgical procedures or injuries. These devices essentially drain aqueous out of the eye into subconjunctival reservoirs created by external plates. These devices differ in size and shape and by the presence or absence of a valve. The non-valved devices include Molteno, Baerveldt, and Shocket. The valved devices include Ahmed, Krupin, OptiMed, and Joseph. The basic surgical technique involves placement of the plate in one of the superior quadrants approximately 8 mm from the limbus, preferrably the superotemporal quadrant to avoid compression on the optic nerve, with the tube placement in the anterior chamber. Approximately, 6-8 weeks post-operatively, a fibrous capsule forms around the plate and regulates flow.
In patients presenting with both cataracts and uncontrolled glaucoma, any of these devices can be placed at the time of cataract surgery. Phacoemulsification with intraocular lens placement can be completed first. Attention is then turned to the superior conjunctiva. A peritomy is performed. The plate of the drainage implant is secured to bare sclera through the preplaced holes. A 23 or 25-gauge needle is used to enter the anterior chamber and this opening is used to place the tube into the anterior chamber (the tube may also be placed in the sulcus in pseudophakic eyes or pars plana in vitrectomized eye). The tube is secured to the sclera and covered with a patch graft. Conjunctiva is then closed. Alternatively, some surgeons prefer to secure the plate first while the eye is firm, complete cataract extraction, and then return to place the tube into the anterior chamber.
Studies have shown combined cataract and tube shunt surgery to be a safe and effective surgical option in certain clinical settings.
- Ex-PRESS miniature glaucoma shunt
Ex-PRESS glaucoma shunt (manufactured by Alcon) is a biocompatible miniature stainless steel implant. It is placed beneath a scleral flap into the anterior chamber to facilitate drainage and form a bleb similar to traditional trabeculectomy. A 25 gauge needle is used to enter the anterior chamber at the gray line under the scleral flap, followed by insertion of this device. Since there is no sclerectomy or iridectomy performed, less inflammation is encountered postoperatively. This modified trabeculectomy can be combined with a cataract surgery. In a recently reported comparative case series of 345 eyes, the surgical success was reported to be 94.8% in the Ex-PRESS only group (mean follow-up: 25.7 months, range 1-46 months) and 95.6% in the Ex-PRESS combined with cataract extraction (mean follow-up:21.9 months (range 1.9-46 months).
Ex-PRESS Shunt in a Phakic Eye
Ex-PRESS Shunt Combined with Cataract Extraction
Photos Courtesy of Sarwat Salim, MD, FACS, University of Tennessee
- Trabectome (Trabeculectomy, Internal Approach)
The Trabectome (NeoMedix Corp., San Juan Capistrano, CA) is a device that uses electrocautery to remove a strip of trabecular meshwork and inner wall of Schlemm's canal under direct visualization with a gonioscopy lens. Therefore, this technique increases outflow through the coventional pathway. Initial studies have shown IOP reduction to the mid-teens when performed alone or with cataract surgery. Trabectome offers a minimally invasive method of lowering IOP in those with mild to moderate glaucoma and does not preclude subsequent procedures. Transient hyphema is the most common complication. Other complications include iridodialysis, cyclodialysis, and elevated IOP.
Canaloplasty is a nonpenetrating surgical procedure designed to enhance the natural outflow pathway through Schlemm’s canal. Canaloplasty involves the creation of a 2-layer scleral flap. A flexible microcatheter with an illuminated beacon tip is then used to cannulate and viscodilate the entire circumference of schlemm’s canal with or without the guidance of ultrasound biomicroscopy. A suture is placed within the canal to tension the inner wall and the associated trabecular meshwork with the intention of restoring natural trabeculocanalicular aqueous outflow. Outcomes of canaloplasty have been reported in conjunction with temporal clear corneal cataract surgery. Initial 1-year results have shown reduction in IOP following combined procedures. Canaloplasty offers the potential for IOP reduction with fewer potential complications than traditional glaucoma surgery. Complications include transient decrease in visual acuity, hyphema, elevated IOP, hypotony, and choroidal effusion.
- Endoscopic Cyclophotocoagulation
Endoscopic cyclophotocoagulation (ECP) can be performed at the same time as cataract surgery using the same surgical incisions. The endoscope provides direct visualization of the ciliary processes on an external monitor. The ciliary epithelium shrinks and whitens during treatment. ECP destroys the ciliary epithelium, thus reducing the production of aqueous humor and lowering the IOP. Most patients receive 270-360° of treatment. ECP has been shown to help reduce IOP by approximately 15% and help reduce the number of IOP lowering medications. The most common complications reported are post-operative IOP spike and transient hemorrhage.
The newer procedures such as Trabectome, Canaloplasty, and ECP offer the advantages of minimally invasive surgery with fewer complications than traditional trabeculectomy or tube shunt surgery. These procedures may be effective for patients with mild to moderate glaucoma, or in helping reduce the number of medications; however, none of these newer techniques have yet shown the same degree of IOP reduction offered by traditional trabeculectomy, trabeculectomy with Ex-PRESS mini shunt, or tube shunt surgery. Any of these procedures can be combined with cataract surgery;however, further studies are needed to determine long-term outcomes.
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