The primary issue with regard to cataract surgery and glaucoma surgery in the same eye is how to position the cataract operation in the management scheme of the patient’s condition. Is it better to choose one sequence and type of surgery before the other, or to combine the two procedures? Although this has been a matter of unresolved controversy, the choice of surgery has been dramatically influenced in the past two decades by three significant and independent advances. The first is the evolution of ever more refined small-incision phacoemulsification techniques and small-profile intraocular lens (IOL) implants – thus allowing for smaller wounds, less postoperative inflammation, and choices for surgical entry sites. The second advance is the demonstrated advantage of using antimetabolites to enhance filtration surgery. Third is the availability of novel glaucoma procedures – non-penetrating glaucoma surgeries1 and endocyclophotocoagulation2 – which have also been combined with small-incision cataract surgery.Together these auspicious developments have resulted in a panoply of surgical solutions far superior to what was available to our patients a generation ago.

Despite the wider spectrum of surgical options, however, the quality of clinical reports, in terms of their epidemiologic and methodological rigor, leave much to be desired.3 In the absence of firm, evidence-based data, personal clinical experience and preference dominate the decision-making process.

be done first and separately; others recommend combination surgery in one procedure. Here, too, results differ between phacoemulsification and extracapsular cataract extraction (ECCE) procedures, as well as whether and how antimetabolites are used. However, rigorous evaluation of the literature on techniques and timing for cataract and filtration surgery has failed to demonstrate convincing evidence of an unequivocally superior approach. Nevertheless, suggestive trends (such as use of mitomycin-C, separate incision sites, and phacoemulsification rather than ECCE) were discerned.6

Similarly, surgical alternatives such as trabeculotomy,2,7–9 and both older and newer forms of non-filtering trabecular surgery11–13 have

been used to control IOP at the time of cataract surgery, but all such reports lack sufficient statistical rigor.

Other considerations are important in individualizing treatment for a given patient. Such issues include the efficacy of and compliance with the current medical regimen, the financial costs or possible side effects of the medical regimen, the chosen target pressure for the eye, the surgeon’s skill and experience, the status of the optic nerve and visual field, and the visual requirements and quality of life that the patient desires to obtain. Every effort should be made in the preoperative evaluation to distinguish between the cataractous and glaucomatous components of a patient’s visual status.This requires dilation for visual field studies, cataract inspection, and detailed ophthalmoscopy.

Cataract surgery in the glaucomatous eye

Glaucoma and cataract often occur together, especially in the elderly, and each condition can influence management of the other. Progressive lens change can mimic progressive visual field loss, reduce visual acuity, and narrow the drainage angle. Glaucoma medications that cause miosis can aggravate visual impairment from cataract; and the now rarely-used anticholinesterase class of miotics can accelerate the development of cataracts. In addition, prior glaucoma surgery leads to a clinically significant acceleration of cataract morbidity in the years following trabeculectomy.4 Thus each of these diseases must be considered when treating the other.

The first consideration is which specific type of glaucoma is being treated; different diseases have different surgical outcomes and complications. Next is the decision regarding the sequence of procedures. Unless a minimal and unpredictable long-term IOPlowering effect of 2–4 mm is deemed sufficient for glaucoma control, cataract extraction alone is usually insufficient to address the pres- sure-lowering (or medication-reduction) needs of the glaucomatous eye.5 Some advocate that either a cataract or filtration procedure

Types of glaucoma and their influence on cataract management

In the absence of peripheral anterior synechiae, eyes with cataract, glaucoma, and progressively narrow angles may respond to approaches other than a combined procedure. Lens size increases with aging and can further narrow an already compromised angle. Laser iridotomy in such patients may facilitate IOP control by relieving any pupillary block component and allowing the angle to widen. Many such patients with primary angle-closure glaucoma (PACG) often show a significant improvement in their IOP control after cataract removal, implying that there is some phaco-

morphic component to their underlying disease, even in the presence of an iridotomy.14–16 Accordingly, if a non-Asian patient with

PACG presents with relatively good IOP control on minimal medical therapy and evidence of greater than 50% available trabecular meshwork, it may be sufficient to proceed with cataract extraction and IOL implantation alone,17 reasonably anticipating a good chance that the glaucoma will remain controlled, if not improved.

An alternate approach combining phacoemulsification with goniosynechialysis has also been advocated, avoiding filtration surgery.18 Diabetic eyes with primary open-angle glaucoma risk worsening

of their ocular health after cataract surgery, with or without lens implantation. In the days of intracapsular cataract extraction, the incidence of neovascular glaucoma was reported to be as high as 9% after intracapsular surgery, a rate nearly identical to that reported for neovascular glaucoma after ECCE surgery in the presence of either an inadvertent or deliberate capsulotomy (11%).19 These rates are in contrast to the much-reduced risk of a rubeotic glaucoma in the presence of an intact capsule. Often, violation of the capsule is unavoidable at the time of cataract/IOL surgery; later it may be unavoidable because of the need for a capsulotomy to maximize either vision or ophthalmologic visualization of the fundus.

Similar findings were reported in a large retrospective study of large-incision ECEE cases in which an important distinction was made as to whether proliferative diabetic retinopathy was present before cataract surgery. If present, there was a 40% rate of neovascular glaucoma and a greater than 20% rate of vitreous hemorrhage related to the cataract extraction.20 Every effort should be made to address a preproliferative retina with panretinal photocoagulation before cataract extraction. In the presence of actual iris neovascularization or proliferative retinopathy, reports on the efficacy of intra­ vitreal bevacizumab (Avastin™) for temporarily inducing neovacular regression in the anterior segment (and by implication its potential utility in the preoperative setting) are encouraging.21–24

Although immediate postoperative problems with fibrin formation and hyphema are seen, the overall success rate for both visual improvement and IOP control is still good in the eyes of diabetic patients.25 There is, however, a higher likelihood of developing pupillary block glaucoma in such eyes.26 Although peripheral iridectomy is currently not routinely performed by most lens implant surgeons (especially with temporal corneal incisions), it is highly advisable that either surgical iridectomy, or access for a postoperative laser iridotomy, be considered in planning cataract surgery in patients with diabetic retinopathy.

Patients that present with pseudoexfoliation are certainly more prone to develop cataracts and have a much higher association of glaucoma (as well as subtle systemic anomalies27) which must be detected before cataract extraction is undertaken.28,29 Many features of the eye with pseudoexfoliation make cataract surgery particularly challenging, including (1) a tendency toward incomplete mydriasis, with a subsequent small pupil that can complicate cataract extraction; (2) a tendency toward multiple surgical challenges – phacodonesis, lens subluxation, zonular laxity or dehiscence, and capsular rupture with lens dislocation and vitreous loss30; (3) a cornea that may be more vulnerable to endothelial damage; (4) a tendency toward hyphema during surgery, and (5) a tendency for unreliable zonular integrity, such that even an in-the-bag lens implant can displace into the vitreous.31 Undiagnosed lens subluxation from weak zonules is often noted intra-operatively,32 but when this condition is anticipated, good results are nevertheless possible with careful phacoemulsification,33 judicious use of viscoelastics, pupillary retractors, capsular tension rings and other advanced cataract techniques.34

Eyes with uveitic glaucoma embrace a wide spectrum of diseases and perisurgical responses. Although cataract/IOL surgery can be performed without incident in eyes with Fuchs’ heterochromic uveitis,35 other reports have observed several specific features of this condition that bear directly on the management of cataractous eyes.36 In more than 103 patients with this condition, some 25% had open-angle glaucoma.37 However, many patients developed

persistent inflammation and peripheral anterior synechiae, rubeosis of the iris and angle, pupillary block, and recurrent hyphemas. When these patients underwent glaucoma surgery, more than half failed standard filtration operations (in the absence of antimetabolites). Similar problems may arise in eyes with other conditions of chronic uveitis and secondary glaucoma.The underlying inflammatory condition, rather than the glaucoma, is responsible for a host of potential postsurgical complications from combined surgery: filtration failure, accelerated posterior capsular fibrosis, cystoid macular edema (CME), fibrinous iritis, etc. Maximal perioperative control of inflammation is essential.38

Occasionally a loose or subluxed lens resulting from traumatic rupture of some of the zonules can be appreciated. In such cases, the lens can shift forward, increasing pupillary block and narrowing the angle. This may be suspected if the chamber is shallow unilaterally, if there is a history of trauma, or if any iridodonesis is evident. In such cases, cycloplegia can deepen the chamber, widen the angle, and allow the surgeon to detect vitreous anterior to the lens if true subluxation exists. Laser iridotomy can be attempted to improve glaucoma control in these eyes, performed away from any area of vitreous prolapse. As with traumatic cataracts, such surgical situations may require complex maneuvers: lensectomy with vitrectomy; capsular tension rings and pupillary retractors; sulcus-IOL support, etc.39

If the angle is open and the cornea healthy, anterior chamber IOL implantation is an option. An alternative is scleral fixation of a posterior chamber IOL behind the iris plane after vitrectomy or loss of the capsule.40–45 This challenging option should be reserved for surgeons skilled in this procedure. Many complications with this technique have been reported in patients undergoing penetrating keratoplasty, including CME, glaucoma exacerbation, and decentered IOLs.46,47 This higher-risk profile merits caution when surgery in the glaucomatous eye is being considered.

Selecting the appropriate surgical approach

For the vast majority of patients with glaucoma and visually significant cataract, there are three choices:

1.Undergo cataract extraction alone, and pay no surgical attention per se to the glaucomatous condition;

2.Undergo glaucoma filtering surgery first and allow full healing before undergoing a second operation for cataract removal;

3.Undergo a single combined cataract and IOL implantation operation at the time of the glaucoma filtering procedure.

Before cataract extraction, it is important to achieve the best possible IOP control, which is defined as a tolerable medical regimen that meets the target pressure, preserving the optic nerve and visual field from progressive worsening. Maximal presurgical therapy also includes the application of selective48,49 or argon laser trabeculoplasty,50,51 whose beneficial effects are not likely to change after cataract surgery.

Cataract surgery alone cannot be expected to provide clinically meaningful IOP control.4,52 Whether using phacoemulsification or

ECCE with IOL, the long-term pressure reduction after cataract surgery is in the order of 2–4 mmHg,16,53–55 with the great major-

ity of eyes requiring the same or an increased glaucoma medical regimen after 1 year.56,57 In a patient with minimal disc and field

change and reasonably well-controlled IOP on a simple medical

regimen, these findings may suggest a course of cataract extraction alone. An attractive approach is to proceed with a temporal, clearcorneal phacoemulsification or small-incision ECCE procedure58; these approaches for cataract-only surgery will not adversely impact later filtration surgery if needed, since the superior conjunctiva remains untouched. In summary, pre-cataract IOP control in glaucoma is unlikely to be lost after cataract-IOL surgery alone and may be, at least, temporarily improved.

Another option is that the glaucoma be surgically addressed first and cataract extraction subsequently undertaken.59 In the presence of marginal cataractous changes or of a complicated glaucoma that has resisted IOP control by medications or prior surgery, establishing successful filtration may well be the first priority.The question is what effect later cataract surgery may have on an established, successful filter.

Most studies report a high likelihood for a subsequent cataract

procedure to compromise a pre-existing filter, with a bleb failure rate as high as 30–40% after lens surgery.60–63 This phenomenon

was reported even with a clear corneal cataract approach designed to avoid disrupting the conjunctiva.63 This suggests that the inflammation caused by lens extraction is detrimental to long-term bleb survival – although the presence of a bleb is helpful in blunting the post-cataract IOP spike.64 Whether the survival of a pre-existing bleb can be enhanced by intraoperative needling or perioperative applications of topical mitomycin-C or subconjunctival 5-fluoro­ uracil (5-FU) has not been systematically studied. Reports of the effect of phacoemulsification-IOL procedures, even performed temporally, uniformally conclude that there is some adverse effect on pre-existing glaucoma control: an increase in postoperative IOP, an increased need for glaucoma medications, or alterations in bleb morphology.65–68 It is therefore realistic to anticipate loss of some IOP control from a pre-existing filtration surgery, to a greater or lesser extent, if the eye later undergoes cataract surgery by either ECCE or phacoemulsification, with or without antimetabolite supplementation of the original bleb.

The arguments for combining trabeculectomy with cataract extraction are persuasive on many grounds. In the absence of pre-existing retinal disease, there is every expectation that excellent visual acuity will be obtained in the overwhelming majority of patients.69,70 Although trabeculectomy in a combined cataract surgery may not be as effective in lowering the IOP when compared with trabeculectomy performed alone, the combined procedure nevertheless provides long-term lower IOPs than when

cataract surgery is performed in a glaucomatous eye without filtration.4,52,71–76

The decision for a combined surgery is not formulaic, and requires a blend of multiple considerations, both positive and negative. We commonly encounter variations of four basic situations, which often present in combinations unique to each eye. These scenarios are:

1.  Cataractous loss of acuity in an eye with glaucomatous disc or visual field changes, unreliably maintaining IOPs below a designated ‘target range’ despite medical or laser management.

2.  Cataractous loss of acuity in an eye requiring medications, where faulty compliance with, allergic sensitivity to, or unsustainable cost of medical therapy recommend a surgical solution to IOP management.

3.  Cataractous loss of acuity in eye with far advanced visual field loss near fixation or with extensive disc damage, which despite adequate IOP control, nevertheless would be at risk

following cataract surgery alone: either at risk for precipitous deterioration by any potential IOP spike, or whose maximal utilization of topical medications precludes additional agents should IOPs rise postoperatively.

4.  Uncontrolled glaucoma in an eye with borderline clinically cataractous changes, anticipating accelerated cataract progression following filtration surgery.4 Such situations might include either the patient’s preference for a single operation rather than a twostaged surgery, or the patient’s physical fraility (usually elderly with multiple medical problems) meriting a single surgical intervention.

As always with any surgery, benefits and risks need be weighed and disclosed: for example, a combined phaco/filter usually requires a longer interval for visual rehabilitation than cataract alone; a trabeculectomy alone usually provides lower IOPs than a combined procedure – yet subsequent cataract surgery often adversely affects prior filtration control.78

A particularly compelling argument for a combined procedure is to protect the glaucomatous eye as much as possible from the likelihood of significant IOP elevations after cataract surgery when performed alone. There is ample evidence for cataract extraction causing significant pressure spikes in glaucoma. One series reported a 2.5 times greater incidence of elevated IOPs in the absence of trabeculectomy than when the combined procedure was performed55; this protective advantage of the concomitant trabeculectomy has also been reported by others.72 Pressure spikes have been detected in nearly two-thirds of patients with pre-existing glaucoma undergoing cataract surgery, in contrast to 10% of normal eyes.56

Nevertheless, the combination of trabeculectomy with cataract extraction does not guarantee the absence of a pressure rise. Krupin and co-workers79 investigated the IOP course in glaucomatous patients who underwent ECCE with or without a concomitant trabeculectomy. They reported an alarming IOP rise on the first day after surgery among the ECCE-only eyes; an IOP rise of 10 mmHg or more occurred in 69% of patients, with threequarters of those eyes measuring an absolute IOP over 25 mmHg. Of the patients undergoing ECCE trabeculectomy, 14% showed an IOP rise of 10 mmHg or more. Of these, 21% showed an IOP over 25 mmHg. Such patients may continue to show IOP fluctu-

ations for several months after ECCE surgery, and close surveillance is warranted.79,80 Similar IOP spikes have also been reported

in up to 40% of eyes using phacoemulsification combined with trabeculectomy and mitomycin-C.81 It should be understood that a combined procedure can definitely reduce, but not predictably eliminate, the problem of intermittent IOP elevations.

Selecting the appropriate procedure: historical considerations

There are few more dramatic illustrations of evolutionary changes in glaucoma surgery in the past quarter-century than the literature on combined cataract and glaucoma surgery. This reflects the advent both of antimetabolite therapy in filtration surgery and of small cataract incisions, in which the same 3–4-mm wound is used for phacoemulsification, IOL insertion, and filtration. Because a spectrum of equipment and techniques may be available to the surgeon at different times, it is useful to understand the results of key technical variations in the development of combined procedures.