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EuroTimes 11-7 new 2 3/7/06 2:28 pm Page 26 Feature ESCRS Symposium Report Lisbon 2005 Glaucoma and Cataract surgery Roibeard O’hEineachain in Lisbon A SYMPOSIUM at the XXIII Congress of the ESCRS addressed the special challenges ophthalmic surgeons face when dealing with co-existing glaucoma and cataract. Session co-chair Stephen A Obstbaum MD commented that ophthalmic surgeons would be encountering more cases of coexisting cataract and glaucoma because of the aging of the population and because of newer diagnostic methods which detect glaucoma at an earlier stage. However, the approaches to the treatment of such co-morbidities are continually evolving and there are currently many unresolved questions as to the optimal surgical procedure, he said. “The approach to the surgical management of these conditions has been controversial and dependent on surgical techniques in vogue at a particular time. The current emphasis on phacoemulsification and foldable IOL implantation and refined methods for filtration surgery has expanded the surgical options to manage these conditions.The introduction of medications that more effectively reduce IOP has added another dimension to the decision-making process.” Current treatment options Prof Carlo Traverso MD followed with an overview of the current surgical approaches in the treatment of patients with cataract and glaucoma. The European Glaucoma Society (EGS) has designed a flowchart of recommended treatments for primary open-angle glaucoma patients with co-existing cataract. The guidelines provide recommendations based on how well IOP is controlled and the extent of damage to the visual field. The recommendations are very straightforward concerning the appropriate treatment for those with very mild or very severe disease, but are somewhat equivocal concerning patients in the more moderate categories. For example, the sole recommendation for treating patients with high IOP who are on multiple medications and have severe visual loss is to perform glaucoma surgery first and phacoemulsification later. In those with normal IOP on monotherapy and only early or moderate visual loss, the guidelines recommend phacoemulsification first followed by glaucoma surgery. Combined approaches gaining favour Prof Traverso noted that historically the management of cataract and glaucoma involved sequential surgery, usually glaucoma surgery followed by cataract extraction once the intraocular pressure was controlled and the bleb evolved. “The success rate of combined extracapsular cataract extraction and glaucoma filtration surgery was not ideal, supporting a rationale for a sequential approach. However, in the last decade, the success of small incision “In the last decade, the success of small incision phacoemulsification and filtration surgery with antimetabolites, has caused a widespread switch from sequential to combined surgery by most glaucoma surgeons” Prof Carlo Traverso MD “In the presence of both cataract and glaucoma you need to think exclusively of the best option for your individual patient,” he said. He noted that among the decisions that a surgeon must make in such cases are whether to use a sequential or combined approach, whether to perform the surgery on one or two sites, and whether to use trabeculectomy or non-penetrating glaucoma surgery. In the case of chronic angle-closure glaucoma a surgeon has also to consider whether IOP can be brought under control by iridotomy or cataract surgery alone. In such cases the cataract itself may play a role in the aetiology of the glaucoma, Prof Traverso said. 26 phacoemulsification and filtration surgery with anti-metabolites, has caused a widespread switch from sequential to combined surgery by most glaucoma surgeons.” Drainage implants Drainage implants are another adjunct to combined procedures that have shown promising results in clinical trials, he noted. One of these is the Glaukos™ Trabecular Bypass Micro Stent.The stent is placed within Schlemm’s canal using an ab-interno procedure. By creating a trabecular bypass, the implant allows the aqueous humour to enter Schlemm’s canal via both the bypass and the trabecular meshwork. It drains out of the canal via collector channels to aqueous and episcleral veins. No bleb is formed. In a study involving 47 patients who underwent phacoemulsification and implantation of the Glaukos microstent, 87% achieved their target IOP six months postoperatively, he said. One-site phacotrabeculectomy One-site phacotrabeculectomy techniques generally commence similarly to a standard trabeculectomy but become more complicated during the phacoemulsification phase of the procedure. When performing such procedures the “When doing combined cataract and glaucoma surgery a patient will be exposed to just one surgical session and there is less risk of IOP spikes just after surgery” Roberto Carassa MD “Implantation of the iStent™ seemed to be safe and effective in reducing the IOP without conjunctival incision or complications traditionally associated with limbal filtering procedures. While these initial results are promising, longer-term follow-up and additional clinical studies are warranted,” Prof Traverso said. Another drainage implant is the ExPRESSTM. This device is positioned at the limbus and acts as a shunt for the aqueous from the AC to the subconjunctival space. Initially this procedure was performed under a conjunctival flap; in case of less than perfect placement of the implant however, the risk of erosion was observed. After favourable reports from studies by Dahan and Carmichael, an implantation technique under a scleral flap is rapidly becoming popular as it prevents the risk of erosion. One-site v two-site surgery Roberto Carassa MD told the symposium that combined approaches are indicated in cases of advanced glaucoma with coexisting cataract. He also maintained that a two-site approach provides the surgeon with greater flexibility and safety and allows the use of their preferred techniques in both the cataract and glaucoma phase of the procedure. “When doing combined cataract and glaucoma surgery a patient will be exposed to just one surgical session and there is less risk of IOP spikes just after surgery. This has implications when we are dealing with advanced glaucoma. With a two-site approach things are certainly easier because we are performing surgery we are used to.” In one-site techniques, phacoemulsification is performed through the filtration surgery incision. Two-site techniques generally involve first performing phacoemulsification in the temporal quadrant and then carrying out standard glaucoma surgery in the upper quadrant, Dr Carassa explained. surgeon first creates a fornix-based conjunctival flap in the superior quadrant, and then makes a groove 3.0-4.0mm deep, 2.0mm posterior to the limbus, followed by dissection of a scleral flap with a crescent knife 1.0mm anteriorly in clear corneal tissue. Following creation of a paracentesis, viscoelastic is injected into the anterior chamber and phacoemulsification is performed through the tunnel opening. An injection of acetylcholine is used to dilate the pupil. After cataract extraction and IOL implantation, the surgeon transforms the tunnel into an “L” or “U” shape with two lateral cuts at the edge of the flap, thereby exposing the internal end of the flap and allowing greater outflow of aqueous.The surgeon performs trabeculectomy using a blade trephine or punch and performs an iridectomy to prevent the iris from plugging the filtration.The procedure concludes with the closure of the scleral and conjunctival flap and aspiration of the viscoelastic. “One-site phacotrabeculectomy is a completely different procedure when compared with standard phacoemulsification or standard trabeculectomy,” Dr Carassa said. One-site combined procedures using non-penetrating surgery involve an additional level of complexity, he noted. In such procedures, the surgeon will generally proceed as with a normal nonpenetrating technique until Schlemm’s canal is exposed, just before cleaving the sclerodescemetic membrane. At this point the surgeon will make a tunnel between the internal and external flap and perform regular phacoemulsification and then cleave the sclero-descemetic membrane and complete the glaucoma surgery as usual. Evidence supports higher efficacy of two-site technique Dr Carassa said that perhaps the only advantage of one-site techniques is that they are faster. He cited two studies that EuroTimes 11-7 new 2 3/7/06 2:28 pm Page 27 Feature Stephen A Obstbaum Roberto Carassa Philippe Sourdille indicated that the two-site technique is more effective in reducing IOP than the one-site technique. In one of the studies (Wyse T et al.: AJO, 1998), patients who underwent the two-site technique had a mean of IOP 13.3 mmHg and required a mean of only 0.2 glaucoma medications. By comparison, patients who underwent one-site surgery had a mean IOP of 15.3 mmHg and required a mean of 0.8 glaucoma medications. In the second study (El Sayyad F et al.: JCRS, 1999), which involved 76 eyes, patients in the one-site group had a mean IOP of 19.1 mmHg after the one-site technique, compared to 17.6 mmHg in the two-site group. Two-site techniques also have numerous safety advantages over one-site techniques, he noted.They involve less manipulation of the conjunctiva and sclera, there is less risk of anti-metabolites entering the anterior chamber, and postoperative suture removal or adjustment will not affect the scleral incision. “The major points affecting the overall outcome of our combined glaucoma and cataract surgery are the use of mitomycinC, two-site technique, and the use of phacoemulsification instead of ECCE. By following all these recommendations we can get the best results with our combined procedures.” The case for sequential surgery Philippe Sourdille MD suggested that combined procedures should be used selectively in order to avoid the use of antimetabolites. “More and more phacotrabeculectomies are routinely performed with application of mitomycin-C and this makes them prone to complications such as hypotony, maculopathy, bleb leak, blebitis and even endophthalmitis with a final loss of visual acuity,” he said. Indications for a sequential approach include glaucomatous eyes with incipient cataracts and those with closed-angle glaucoma. In eyes with incipient cataracts, where visual impairment is mild and cataract surgery is not urgent, he recommended the use of non-penetrating glaucoma surgery techniques because they are less cataractogenic than standard trabeculectomy. “In the AGIS study, at five years an incidence of 87% of cataract was noted after trabeculectomy. In contrast, all the published literature indicates a rate less than 10% after non-penetrating surgery.” In eyes with primary closed-angle glaucoma and cataract he recommended first removing the cataract and assessing the effect of the procedure on the IOP. I Howard Fine Alan Crandall Influence of cataract surgery on IOP When performing cataract surgery in eyes that have undergone previous filtration, surgeons should consider the effect the procedure will have on the eye’s IOP, he said. Several studies have shown that cataract procedures increase IOP slightly in about half of eyes for a year or more. “More and more phacotrabeculectomies are routinely performed with application of mitomycin-C and this makes them prone to complications such as hypotony, maculopathy, bleb leak, blebitis and even endophthalmitis with a final loss of visual acuity” Philippe Sourdille MD “You may consider that 2.0mm in IOP elevation would not be significant, but should the IOP already be above the target pressure at the time of cataract surgery this 2.0 mmHg rise can be deleterious to the visual field.” Dr Sourdille recommended carefully watching the influence of infusion on the bleb height during surgery. In this way it is possible to assess whether to consider additional steps such as bleb revision, antimetabolite injection, scleral flap revision or reopening or re-operation at a later time. “IOP elevation will be dangerous for the optic nerve and hypotony can be deleterious to the filtration so we should be very careful to ensure the postoperative tightness of the wound and remove all of the viscoelastic and monitor postoperative IOP and inflammation.” Dr Sourdille noted that most of the published literature suggests better IOP control can be achieved with trabeculectomy than with phacotrabeculectomy, whether or not antimetabolites are used. However, he noted that some investigators have reported results equivalent to those of trabeculectomy alone in combined procedures involving deep sclerectomy. “Routine phacotrabeculectomy does not apply to all cases of coexisting cataract and glaucoma. Sequential procedures should be considered in glaucomatous eyes with Robert Stegmann incipient cataract and in such cases noncataractogenic glaucoma surgery should be the procedure of choice” he added. Management of the miotic pupil Turning to some of the specific challenges faced by surgeons dealing with cataracts in glaucoma patients, I Howard Fine MD addressed the issue of miotic pupils. “One of the problems with cataract surgery in glaucoma patients is the frequent incidence of small pupil, which can often be intractable.” He described his own approach in such eyes, which he said involves proceeding from the least invasive to the more invasive approaches until the pupil can be dilated sufficiently for phacoemulsification. In such eyes, he commences his procedures as he would in an eye with a normal pupil. Under the upper eyelid he places a surgical sponge dripped in a solution containing a local anaesthetic (Marcaine-MPF 0.75%, 12.5cc), mydriatics (Mydriacyl 1.0%, 2.5cc) (Cyclogel 2.0% 2.5cc), anti-inflammatories (Flurbiprophen 0.03%, 2.5cc) and antibiotics (Vigamox 0.5cc, Alcon).The sponge is left under the eyelid, which he tapes closed for 15 minutes. If the pupil does not seem to dilate adequately he adds additional mydriatic drops. In patients prone to floppy iris syndrome because they are receiving the agent tamusolin (Flomax, Boerhinger Ingelheim), patients are prescribed atropine 1% one week before surgery. “In these cases I believe that bimanual microincision phaco is an added advantage because although the iris will still come to the incision it doesn’t extrude and because of the ability to separate infusion from the phaco tip we can have the fluid circulating above the iris. “ Lester hooks If the pupil still remains inadequately dilated, Dr Fine then begins a series of additional steps, starting with the use of two Lester hooks. Injection of viscoelastic can also aid in pupil dilation. “It is important to stretch the pupil slowly because it is easy to damage the iris. It’s important also to stay in a horizontal plane so as not to damage the zonules. I try to avoid going into the incision location with stretching because we tend to get ruptures in the sphincter, which tend to be a little bit floppy.We also get less chance of extrusion if we stretch it in meridians that are not in the meridian of the incision or the sideport.” If this manoeuvre is insufficient Dr Fine said that he will then proceed to use a Beehler pupil dilator.The device comes in two forms, one with three prongs, which fits through 2.5mm and another with three prongs, which requires a 3.0mm incision. Both have a hook at the base of the cannula, which allow the surgeon to reflect the subincisional portion of the pupil. “The prongs will essentially stretch the pupil closer to the dimension of the circumference of the base of the iris rather than just the diameter of the pupil. Slow stretching is very important and the use of viscoelastics following the stretching of the pupil adds to the increased size of the pupil and very often it allows you to perform surgery in the usual manner in an inhospitable pupil.” Hydro-express the cataract An additional technique is to hydro-express the cataract into the plane of the pupil so it is vertical rather than horizontal.The bulk of the cataract will hold the pupil open throughout the case. Using bevel down phacoemulsification at this point prevents fluid from going under the iris. “In situations like this, you don’t disassemble the nucleus by chopping or cracking.We just try to phaco it from inside out with a gradual diminution of the size of the cataract bulk. Another benefit is that all the energy goes toward the cataract and none toward the corneal endothelium or toward the trabecular meshwork.” If the pupil should constrict after removal of the nucleus there can be some difficulty in visualising the cortex. Injection of Healon 5 (AMO) will usually re-dilate the pupil adequately.The cortex can then be stripped circumferentially following the margin of the capsulorhexis. However, it is important to disallow clearance of occlusion to avoid aspiration of the viscoelastic, he said. Stripping the pupillary membrane is another technique that some surgeons find useful, he said. A fibrotic membrane is often the cause of the pupil’s miosis. Another technique is to make mini-sphincterotomies with Rappazzo scissors, making incisions that are halfway through the thickness of the sphincter but are full thickness in the anterior and posterior dimension. “After making these minisphincterotomies we stretch these areas where we cut.This leaves a peripheral rim of muscular tissue in the pupillary sphincter, which allows for normal function postoperatively. I always reduce the pupil mechanically to reduce adhesions between pupil and capsule physiologically functional and cosmetically acceptable.” Dr Fine said that, as a final resort, he will use a pupillary expander ring implanted with either two forceps or with an injector. By providing a broad area of contact against the iris, the rings can safely and efficiently dilate very weak and most miotic pupils without damaging the iris. 27 EuroTimes 11-7 new 2 3/7/06 2:28 pm Page 28 Special Focus Enhanced viscocanalostomy Robert Stegmann MD concluded the symposium with a description of his new enhanced viscocanalostomy technique 28 While glaucomas represent a very heterogeneous group of conditions, one factor they all have in common is that they involve a collapsed, dysfunctional Schlemm’s canal, Dr Stegmann noted. Trabeculectomy, along with most of the non-penetrating techniques, are fistularising procedures, which direct the aqueous fluid to the conjunctiva where a filtering bleb is formed. In contrast, viscocanalostomy provides a channel for aqueous through the Descemet’s window into a scleral lake, from which the fluid drains out through Schlemm’s canal as it does in the normal healthy eye. Up to now the problem with viscocanalostomy has been that it has not been possible to open Schlemm’s canal throughout its complete circumference. However, a new microcatheter has made it possible to not only expand the canal completely but also to draw a suture through the canal to insure its long-term patency. The new microcatheter is produced by iScience and has a diameter of 200 microns and an atraumatic soft tip. A helium-neon light source shone through an optical fibre illuminates the catheter tip, which also contains a polyamide lumen for the injection of sodium hyaluronate. In addition, a new high-resolution ultrasound system, also produced by iScience provides accurate localisation of Schlemm’s canal and can also provide confirmation of the success of the procedure. Microcatheter technique When using the microcatheter, Dr Stegmann commences as he would with a conventional viscocanalostomy procedure. He first dissects a parabolic flap in the sclera to a depth of 250 to 300 microns and then dissects a further 300 or 400 microns down to a level that is just superficial to the choroid to create a scleral lake. He then dissects forward to reveal the canal of Schlemm and creates a Descemet’s window. He then gently insufflates the surgically created ostia with a viscoelastic, which serves as a lubricant to allow the safe insertion of the microcatheter. As he passes the microcatheter through the canal of Schlemm he uses a micrometer syringe to deliver 0.02ml of viscoelastic per 1/8 turn on the micrometer screw. Once he has passed the microcatheter 360 degrees through Schlemm’s canal and it emerges at the operative site he attaches two 10-0 prolene sutures to the catheter, which he then draws back through the canal. After withdrawing the catheter, he ties off the ends of the sutures with a special slipknot to create 20 grams of tension. “This opens the canal internally so that the ostia you have created will not close postoperatively,” he said. He noted that the high success rate in his African glaucoma patients, among whom the mean pre-operative IOP is 47-49 mmHg, suggests it should be even more effective in Caucasian glaucoma patients, among whom the mean IOP is 24-25 mmHg. Dr Stegmann said that he has had a success rate of about 79% in his African population, while his associates in America are reporting success rates of around 92%. “What is most encouraging is that with a maximum follow-up of 11 months, 92% of cases have reached episceral venous pressure.” [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Catheter just prior to insertion. Note the illumination of the catheter tip from the helium-neon light source The catheter tip at 9 o'clock. The illuminated tip informs the surgeon of the catheter’s location throughout the procedure The catheter tip at 6 o'clock. The illuminated tip informs the surgeon of the catheter’s location throughout the procedure The catheter being withdrawn after passing through the complete circumference of Schlemm’s canal Courtesy of Clive Peckar FRCS FRCOphth Capsular tension rings Alan Crandall MD followed with a presentation on the use of capsular tension rings in eyes with weak zonules, a condition that can occur in eyes of patients with conditions that make them prone to glaucoma and can also occur as a result of glaucoma surgery. “Capsular tension rings are used in about five per cent of cataract procedures and convert a high risk case into a routine case. They are designed to maintain the capsule’s contour and stretch the posterior capsule when there is zonular dehiscence or rupture occurs after blunt or penetrating injury, or surgical trauma, or when there is inherent zonular weakness.” Capsular tension rings can be used for intraoperative support and then removed later, or can be sutured in. In addition to facilitating IOL implantation, they promote IOL centration and can be used for resuturing a late dislocated in-the-bag intraocular lens. Among the indications for capsular tension rings are systemic conditions such as Marfan’s syndrome and WeillMarchesanie syndrome, ocular conditions such as pseudoexfoliation and high myopia, and eyes that have undergone previous glaucoma filtration surgery and previous RK. There are various models of capsular tension ring available.There are the standard capsular tension rings by Morcher and Ophtec, which include variations for highly myopic eyes.There are also the Sundmacher and Rasch Rosenthal Morcher models, which incorporate artificial irises for aniridia or iris trauma. Of particular value in the treatment of cataracts in glaucoma patients is the Cionni Capsular Tension Ring (Morcher), which has a special eyelet that sits above the capsule for scleral fixation.There are also new capsular tension ring segments that are smaller and are easier to use intraoperatively, and which can also be sutured to the sclera, Dr Crandall said. Capsular tension rings may be inserted at any stage of a phacoemulsification procedure, either with a Geuder injector or manually with forceps. Grieshaber iris hooks may be needed to suspend the bag prior to insertion of the ring. Hydrodissection facilitates the procedure and “slow motion” phaco is necessary, he noted. Inserting the rings prior to phaco affords greater nuclear stability although it is difficult in cases with dense lenses where there is a risk of iatrogenic zonular damage. The presence of the ring can also make cortical removal more challenging. Inserting the rings after phacoemulsification is generally easier. Iris hooks should be used during phaco and cortical removal, Dr Crandall advised, adding: “Early placement of a CTR does result in some bag torque and zonular stress therefore we suggest using it as late as you can during the procedure.”