Perspectives in
`trabecular surgery
`
`PHILIPP C. JACOBI, THOMAS S. DIETLEIN,
`GUNTER K. KRIEGLSTEIN
`
`Abstract
`
`The aim of trabecular surgery is to selectively
`combat the diseased structure central to the
`pathogenesis of chronic open-angle glaucoma,
`thereby reducing potential hazards during and
`after conventional filtering procedures. This
`overview considers new techniques in ab
`interno trabecular surgery. Special emphasis is
`placed on the description of each novel
`technique, its instrumentation, presumed
`mechanism of action and clinical results.
`Trabecular aspiration is evaluated as a method
`of clearing intertrabecular spaces of
`extracellular debris in pseudoexfoliation
`glaucoma with or without simultaneous
`cataract surgery or goniocurettage, while laser
`trabecular ablation is discussed for the
`treatment of absolute glaucomas. Where
`corneal haze has formed visualisation of the
`anterior chamber angle structures and
`trabecular surgery is performed with the aid of
`a microendoscope. Although the results are
`very promising it should be understood that
`some of these procedures are still in the
`experimental phase and are undergoing
`careful clinical evaluation, leaving plenty of
`room for refinements and further
`developments.
`
`Key words Goniocurettage, Microendoscopy,
`Trabecular aspiration, Trabecular photoablation
`
`Enormous progress has been made in
`understanding the complexity of the underlying
`causes of chronic open-angle glaucoma.
`However, indisputable concepts for effective
`treatment are still rare. To date, conventional
`filtering surgery remains the mainstay of
`surgical therapy in the management of
`glaucoma not controlled by medication.!
`Unfortunately, treatments involving full­
`thickness filtration are scarcely selective since
`healthy structures not primarily involved in the
`disease process are subject to surgical
`intervention. The application of adjunctive
`antimetabolites for inhibition of undesired
`episcleral fibroblastic proliferation dramatically
`increased the success rates for filtering
`procedures, but had the disadvantage of
`exacerbating serious side-effects, such as flat
`
`anterior chambers, prolonged post-operative
`hypotony and late endophthalmitis from
`infected filtering blebs?,3
`Mircosurgery on Schlemm's canal and the
`human aqueous outflow system for controlling
`intraocular pressure (lOP) in chronic open­
`angle glaucoma has been evolving over the past
`few decades. Theoretical considerations indicate
`that production of approXimately 10 to 15
`fistulae, each 10 !Lm in diameter, between the
`anterior chamber and Schlemm's canal should
`restore normal outflow facility in open-angle
`glaucoma.4 The basis for most of the current
`approaches to microsurgery of Schlemm's canal
`is the finding by GrantS that the largest
`proportion of resistance to outflow is located
`within the trabecular meshwork, namely the
`cribriform layer, and can be eliminated by
`incising the trabecular meshwork and entering
`Schlemm's canal. If one agrees that the site of
`the pathological resistance to aqueous humour
`outflow is this tissue, its partial removal, taking
`the utmost possible care not to damage the
`surrounding chamber angle structures, could be
`a new alternative in antiglaucomatous surgery.
`This sort of selective non-penetrating trabecular
`surgery would be equivalent to internal
`filtration surgery without transscleral drainage
`of aqueous humour into the subconjunctival
`space, and would thereby reduce the incidence
`of post-operative complications typically
`associated with filtering procedures.
`This review discusses different ab interno
`trabecular microsurgical techniques that are
`designed to facilitate outflow along its natural
`pathway. Each new technique is described in
`detail, newly developed instrumentation is
`discussed, and the presumed mechanisms of
`action are outlined. However, the reader must
`understand that none of these new
`microsurgical procedures threatens to replace
`conventional filtering approaches, since they are
`still in the experimental phase and under
`careful clinical evaluation, and there is plenty of
`room left for further refinements and
`developments. We hope this article will give
`impetus to the search for alternative strategies
`in antiglaucomatous surgery, and focus
`attention more closely on the diseased target
`structure in chronic open-angle glaucoma: the
`trabecular meshwork.
`
`P.c. Jacobi
`T.S. Dietlein
`G.K. Krieglstein
`University Eye Hospital
`University of Cologne
`Cologne, Germany
`
`Philipp C. Jacobi, MD �
`Department of
`Ophthalmology
`University of Cologne
`Joseph-Stelzmannstrasse 9
`D-50931 Cologne, Germany
`
`Tel: +49221 4784345
`Fax: +49221 4784347
`
`Eye (2000) 14, 519-530 © 2000 Royal College of Ophthalmologists
`
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`Goniocurettage
`
`The underlying concept of goniocurettage is to remove
`rather than incise or disrupt pathologically altered
`trabecular meshwork and to open a route for aqueous
`humour to egress either into Schlemm's canal or, where
`the external wall of the canal is damaged, to ooze out
`through microsplittings in the posterior scleral wall.6 The
`procedure is conceptually similar to goniotomy, except
`that trabecular tissue is scaped away from the scleral
`sulcus using an instrument similar to a microchalazion
`curette (Fig. 1). The gonioscraper consists of a small
`handle and a slightly convex arm for intraocular use and
`closely resembles a cyclodialysis spatula. However, the
`tip of the instrument is shaped like a minature bowl,
`300 fLm in diameter, with sharpened edges. To abrade
`clockwise and counter-clockwise, the scoop is vertically
`angled at 90° to either side.
`Goniocurettage is usually performed under direct
`visualisation of the anterior chamber angle through an
`operating microscope and a surgical gonioscopy lens
`(Fig. 2). Following injection of viscoelastic, the
`gonioscraper is inserted into the anterior chamber
`through a clear corneal incision and directed against the
`trabecular meshwork on the opposite side. The scraper is
`lightly passed over 2 to 3 clock-hours to either side of the
`nasal circumference of the chamber angle. Great care is
`taken while peeling off the uveal meshwork not to
`
`(a)
`
`(b)
`
`Fig. 2. Ab interno goniocurettage is performed with the aid of an
`operating microscope under gonioscopic observation.
`
`traumatise adjacent intraocular structures, such as the
`corneal endothelium or the base of the iris.
`Intraoperatively, ragged strings of trabecular tissue can
`be seen to be removed by gonioabrasion, leaving an
`irregular pattern of a glistening white band
`corresponding to the denuded grey-white scleral sulcus
`(Fig. 3). At the end of the procedure, viscoelastic along
`with abraded trabecular debris is removed by means of
`irrigation-aspiration.
`Morphological analysis of the treatment zones in
`human donor eyes clearly indicated the potential efficacy
`of goniocurettage for completely removing the trabecular
`meshwork.6 From light microscopy of histological
`sections it is evident that, in addition to the peeling of the
`trabecular meshwork, goniocurettage also causes
`damage to intracanalicular septa and the endothelium of
`the external wall of Schlemm's canal, and in some
`instances a disruption along the posterior wall of
`Schlemm's canal. Flaps of uveal tissue, capable of
`returning to their predissection position, were not
`observed in the specimens. Scanning electron microscopy
`shows that the trabecular meshwork is pulled away from
`its attachments, leaving ragged structures of Schlemm's
`canal within the scleral sulcus exposing bare sclera
`(Fig. 4).
`
`Fig. 1. (a) The tip of the 'gonioscraper'. The external diameter of the
`bowl is 300 j.Lm and its edges are sharpened. (b) The intraocular arm of
`the gonioscraper is convex to avoid inadvertent damage to the iris-lens
`diaphragm.
`
`Fig. 3. After gonioabrasion, an irregular pattern of a glistening white
`band corresponding to the 'denuded' grey-white sulcus scleralis
`appears (black arrows).
`
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`minimal amount of blood staining the chamber angle
`could be seen to disappear within 2 or 3 days after
`surgery. However, inadvertent damage to prominent
`vessels within the chamber angle created a more serious
`intraoperative complication. Marked bleeding within the
`anterior chamber angle occurred in 16% cases leading to
`interruption of the procedure in 8%. Even careful
`observation of the target area cannot prevent this in
`every case. Tears in Descemet's membrane might be
`caused by the tip of the probe when it comes too close to
`the endothelium during rotation. Descemet's tears were
`usually small and were not followed by corneal oedema.
`Descemet's tears may, however, remain visible for a long
`period of time when blood-stained. Serious problems
`such as a shallow anterior chamber, choroidal
`haemorrhage or detachment, endophthalmitis, and
`leakage of aqueous humour under the conjunctiva did
`not occur after goniocurettage.
`In conclusion, this prospective study indicates that
`goniocurettage is an effective surgical treatment for
`various forms of chronic open-angle glaucoma, even in
`eyes with previously failed trabeculectomies. It is
`independent of conjunctival wound healing responses and
`associated with a relatively low risk profile. Although
`post-operative pressure levels after goniocurettage remain
`in the high teens, even with medication, this new
`procedure may in the future be considered as an
`alternative surgical treatment in selected cases of
`glaucoma. Further studies on glaucoma cases with an
`overall better prognosis and an evaluation of the effects of
`goniocurettage on visual field testing are required.
`
`Laser trabecular ablation
`
`Since laser trabeculopuncture was introduced by
`Krasnov in 1973,11 various lasers, such as the argon or
`Nd:YAG laser have been used in trabecular surgery.
`However, the effectiveness of these procedures decreases
`with time.12,13 Berlin and associates14 were the first to
`investigate the potential for photoablation of the
`trabecular meshwork using a XeCI-excimer laser,
`emitting at 308 nm, which can be used in conjunction
`with an optical fibre system. Vogel and co-workers15
`found that in 4 of 6 glaucomatous eyes lOP was reduced
`by 11 mmHg over a follow-up period of 5 months,
`whereas in 2 patients the lOP increased by 2 mmHg
`despite additional antiglaucomatous medication.
`However, it seems that the high initial outlay and
`running costs of such gas laser modules, as well as the
`potential hazards of intraocularly applied ultraviolet
`radiation, may render them unsuitable for routine use.
`Hill and associates16,17 have recently proposed a
`promising method for treating the trabecular meshwork
`directly. They described the use of photoablative mid­
`infrared lasers to create multiple micro-openings through
`the trabecular meshwork into Schlemm's canal with
`minimum collateral thermal damage. The authors
`achieved smooth ablations of trabecular tissue for the
`macropulsed Er:YAG (2.94 fLm) and the Er:YSSG
`(2.79 fLm) laser and termed the procedure laser
`
`522
`
`trabecular ablation. Radiation emitted from mid-infrared
`lasers is known to elicit a relatively narrow zone of
`thermal damage in biological tissue, with little
`mechanical stress. Among these the Er:YAG laser,
`emitting at a wavelength close to the absorption peak of
`water in the mid-infrared spectral region, has a short
`absorption length (25 fLm) in water-containing tissue and
`ablates with minimal thermal damage to contiguous
`structures.18,19 The Er:YAG laser thus seems to emit at
`the most favourable wavelength. It has been suggested
`that the removal of a larger segment of the trabecular
`meshwork in laser trabecular ablation may impair
`wound repair mechanisms and be another cause of
`surgical failure.17
`Laser trabecular ablation in porcine cadaver eyes,
`using a macropulsed Er:YAG laser (200 fLS; 5 mn,
`resulted in full-thickness ablation craters, with consistent
`ablation widths of 200-300 fLm; collateral thermal
`damage was less than 30 fLm (Fig. 5). Moreover, outflow
`facility measurements revealed a significant increase
`from 0.128 :±: 0.041 fLm min-1 mmHg-1 in controls to
`0.308 :±: 0.093 fLl min-1 mmHg-1 in treated eyes, thereby
`lowering outflow resistance by 70% from baseline - an
`achievement of clinical relevance,z°
`Although in vivo studies in rabbits revealed that
`ablation craters in the trabecular meshwork closed up
`within less than 60 days,21 preliminary results of laser
`trabecular ablation in adult open-angle glaucoma are
`promising. Dietlein and co-workers22 performed ab
`interno Er:YAG laser trabecular aspiration in 14 patients
`suffering from terminal optic nerve atrophy due to
`medically uncontrolled open-angle glaucoma, with a
`maximum follow-up of 14 months. Under gonioscopic
`observation each patient received 15 to 20 single laser
`pulses (6 mn to the trabeculum delivered via a 320 fLm
`quartz fibre endoprobe (Fig. 6). No patient was treated
`more than once, and all experienced a significant
`decrease in lOP and reduction in adjunctive medication.
`As a rule, reflux of blood from Schlemm's canal occurred
`at the site of laser ablation. Moderate reflux bleeding was
`
`Fig. 5. Scanning electron microscopy following laser trabecular
`ablation in porcine cadaver eyes. The macropulsed Er: Y AG laser
`ablation results in full-thickness ablation craters with ablation widths
`varying between 200 and 300 JLm; collateral thermal damage is less
`than 30 JLm.
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`anterior chamber angle in many cases. Removal of the
`cloudy corneal epithelium does not always improve
`visibility, so that gonioscopic identification of the
`anterior chamber angle structures is not possible in every
`case. Intraocular microendoscopy is an exciting
`development that affords the surgeon new opportunities
`in the management of vitroretinal disease,25
`cyclophotocoagulation,26 complicated transscleral
`intraocular lens fixation,27 and possibly in the
`management of antiglaucomatous trabecular surgery.
`Following earlier in vitro studies, anterior segment
`microendoscopy has already been successfully applied as
`a diagnostic too128,29 or in combination with various
`trabecular microsurgical procedures.30,31
`Recently, we conducted a prospective, non­
`randomised study in human glaucomatous eyes in order
`to assess the surgical technique, practicability, surgical
`outcome and intraoperative complication rate of
`microendoscopic trabecular surgery.32 In 15 patients with
`medically uncontrolled open-angle glaucoma and
`advanced corneal opacification, visualisation of the
`anterior chamber angle structures and trabecular surgery
`was performed under microendoscopic control.
`Exclusion criteria were a visual acuity of more than
`20/200 in the treated eye, worse visual function in the
`contralateral eye, a history of uveitis, herpetic keratitis,
`ocular trauma, narrow angle, traumatic or rubeotic
`glaucoma and young age (less than 40 years).
`In this study, we used an ophthalmic microendoscope
`(Endo Optiks, Little Silver, NJ), which is basically a
`triple-function endoscope consisting of three fibre
`groupings: the image guide (3000 and 10 000 pixels), the
`light guide and a diode laser guide. In the current
`experiments the laser guide was disconnected. This
`endoscope came with a 20 gauge (0.88 mm diameter)
`probe, providing a 70° field of view and a depth of focus
`ranging from 0.5 to 15 mm. Additionally, an 18 gauge
`(1.2 mm diameter) endoscope with the same three
`components was used. The field of view in this iteration
`is 110° with a depth of focus ranging from 1 to 30 mm.
`The advantages of the larger-diameter endoscope are the
`greater clarity provided by the image bundle and the
`panoramic field of view that it creates. The
`microendoscope is used in conjunction with a light
`source, video camera, television monitor and video
`recorder. Both intraocular endoscopes were gas-sterilised
`before surgery. Trabecular surgery was performed using
`either laser trabecular ablation or goniocurettage.
`Patients were randomly assigned to treatment with one
`of the two techniques.
`Seven eyes were treated by means of laser trabecular
`ablation and 8 eyes by means of goniocurettage. The
`average age at surgery was 69.7 ± 9.1 years (mean ± SD)
`(range 55-83 years). Twelve of 15 patients had
`undergone previous antiglaucoma procedures involving
`the conjunctiva. Four eyes had failed trabeculectomy
`with adjunctive mitomycin C and 8 eyes had argon laser
`trabeculoplasty before trabecular surgery. The average
`follow-up time was 21.1 ± 3.0 months (range 19-28
`months).
`
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`
`Fig. 6. Under gonioscopic observation the quartz fibre tip of the
`endoprobe is inserted into the anterior chamber and directed against the
`trabeculum. The ablation process is initiated under tissue-instrument
`contact.
`
`assessed as an intraoperative sign of full-thickness
`perforation of Schlemm's canal, which is continuous with
`episcleral veins. No patient had heavy bleeding,
`hyphaema formation or undue inflammation post­
`operatively. The minimal amount of blood staining of the
`chamber angle could be seen to disappear within 2-3
`days after surgery. Melamed and associates23,24 also
`reported blood reflux as an intraoperative result of
`photodisruptive openings into Schlemm's canal. Post­
`operative gonioscopy of the treatment area revealed
`neighbouring ablation craters within the trabecular
`meshwork, easily identified in most patients by a distinct
`loss of pigmentation (Fig. 7). Long-term studies on laser
`trabecular ablation in adult glaucoma are now being
`performed to assess the full potential of this promising
`procedure.
`
`Microendoscopic trabecular surgery
`
`Of great importance to the success of trabecular surgery
`is a clear cornea to observe and identify the fine details of
`anterior chamber angle structures. Unfortunately, the
`scarring and corneal oedema frequently associated with
`lOP dysregulation hamper the gonioscopic view of the
`
`Fig. 7. Post-operative gonioscopy of the treatment area reveals
`neighbouring ablation craters within the trabecular meshwork, easily
`identified by a distinct loss of trabecular pigmentation.
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`Fig. 8. Following the injection of viscoelastic, the microendoscope is
`introduced into the anterior chamber through a 1.2 mm paralimbal
`clear corneal tunnel incision.
`
`Intraoperatively, the microendoscope was introduced
`into the anterior chamber through a 1.2 mm paralimbal
`clear corneal tunnel incision followed by the injection of
`viscoelastic (Fig. 8). While the endoscope was pushed
`forward to the pupillary margin, the posterior cornea
`and anterior lens surface simultaneously came into view
`on the video screen. The goniocurette or the laser
`endoprobe entered the anterior chamber through a
`second paralimbal paracentesis. Following insertion the
`surgical instruments came instantly into view on the
`monitor, helping to avoid inadvertent damage to any of
`the internal structures as the endoprobes were advanced
`into the anterior chamber angle. When using the Er:YAG
`laser the He-Ne aiming beam of the laser was readily
`identified on the trabecular meshwork, and the tip of the
`microendoscope moved between 0.5 to 7.0 mm away
`from the chamber angle structures (Fig. 9).
`
`Fig. 9. Endoscopic view of the anterior chamber angle as the laser
`probe approaches the trabecular meshwork. Laser ablation craters can
`be distinguished by a 'whitening' of the trabeculum. Resolution and
`clarity of the endoscopic picture are somewhat higher when observed in
`real time than they are in a freeze-frame.
`
`524
`
`Fig. 10. Endoscopic view of the anterior chamber angle as the
`gonia curette approaches the trabecular meshwork. The white reflex at
`the tip of the instrument is the bowl of the curette.
`
`Laser trabecular ablation at 6 mJ pulse energy
`reproducibly yielded round to oval tissue whitening
`post-operatively. At the time of treatment, all 7 eyes
`demonstrated low-thermal photovaporisation of the
`trabecular meshwork and various degrees of exposure of
`the outer wall of Schlemm's canal. A reflux of blood from
`Schlemm's canal into the anterior chamber was observed
`at the treatment site. Gas bubble formation and heavy
`pigment dispersion did not, however, occur. No frank
`hyphaemas were detected.
`In endoscopically controlled goniocurettage the
`minicurette was observed to pass alongside the scleral
`spur, tending to push trabecular tissue ahead of it, but
`usually leaving the anterior portion of the trabecular
`meshwork and Schwalbe's line in place (Fig. 10).
`Endoscopically, it was possible to see strings of
`trabecular tissue being removed intraoperatively, leaving
`a white band corresponding to the scleral sulcus.
`Complications included a small peripheral
`descemetolysis and a reflux of blood from Schlemm's
`canal within the treatment area, neither of which had any
`further sequelae.
`lOP was reduced in all eyes as a result of surgery. The
`average pre-operative lOP was 34.5 ± 6.1 mmHg
`(mean ± SD) (range 27-46 mmHg), compared with
`18.5 ± 3.0 mmHg (range 13-23 mmHg) after surgery at
`last follow-up. The average number of glaucoma
`medications used before surgery was 2.3 ± 0.6
`(mean ± SD) while the average number used post­
`operatively was 1.1 ± 0.7. Considering all treated eyes,
`the mean pressure reduction after endoscopic trabecular
`surgery was 15.9 ± 4.3 mmHg (range 9-23 mmHg). This
`represents a 46% decrease from baseline (�%), which is
`statistically significant (p < 0.05). There was no
`statistically significant difference in pressure-reducing
`effect between eyes receiving laser goniopuncture and
`those treated by goniocurettage. Transient phases of
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`hypotony (lOP in the 0-6 mmHg range), choroidal
`effusion or flattening of the anterior chamber were not
`observed.
`Since the surgeon was applying microendoscopy of
`the anterior segment of the eye for the first time, great
`caution had to be exercised during the procedure. Video
`monitor control and non-stereoscopic viewing
`demanded particular technical adaption. In our series,
`however, substantial complications related to the
`endoscopy itself were not observed. Patients enrolled in
`this study were treated only once and experienced a
`decrease in lOP and reduction in adjunctive medication.
`Moderate reflux bleeding occurred in most patients and
`was assessed as an intraoperative sign of full-thickness
`perforation of Schlemm's canal. None was detected to
`have heavy bleeding, hyphaema formation or undue
`inflammatory response. The minimal amount of blood
`staining of the chamber angle was seen to disappear
`within 2 or 3 days after surgery. However, before this
`procedure can be considered as a viable concept in
`glaucoma surgery, i.e. in the treatment of primary
`infantile glaucoma, further experience in a greater
`number of patients is needed.
`
`Trabecular aspiration
`
`Despite the many different causes of secondary
`obstructive glaucomas, such as pseudoexfoliation (PEX),
`pigmentary, phacolytic and silicone oil glaucoma, all
`these conditions develop via the same pathogenetic
`pathway: lOP dysregulation arising from trabecular
`obstruction. Extraneous material within the anterior
`chamber eventually causes obstruction of the trabecular
`outflow channel, leading to a non-physiological pressure
`increase. Assuming that the primary pathogenetic factor
`in secondary obstructive glaucoma is obstruction of
`filtering pores of the trabecular meshwork (which, over
`time, become increasingly dogged by deposits of debris
`and pigment granules), a surgical procedure that relieves
`the uveal meshwork of its obstruction should, in theory,
`be effective.
`In previous studies, we described a new form of non­
`filtering glaucoma surgery - trabecular aspiration -
`designed to facilitate trabecular outflow in secondary
`glaucomas such as PEX glaucoma?3-35 Morphological
`analysis of the trabecular aspirate dearly illustrated the
`efficacy of trabecular aspiration for removing
`pretrabecular and intertrabecular debris?3 Trabecular
`aspiration in combination with extracapsular cataract
`extraction substantially lowered the lOP in a small group
`of cataractous eyes complicated by medically
`uncontrollable PEX glaucoma?4 Moreover, when applied
`as primary therapeutic surgical intervention in PEX
`glaucoma, this procedure also turned out to be an
`effective tool for pressure management.35 These early
`results were obtained with a form of trabecular
`aspiration requiring a single-handed irrigation­
`aspiration device and a deep anterior chamber
`intraoperatively in order to avoid contact with the
`anterior surface of the crystalline lens in phakic eyes
`
`Fig. 11. Single-handed irrigation-aspiration device designed to sweep
`over the trabecular meshwork with negative suction pressure, thereby
`clearing the intertrabecular filtering pores in pseudoexfoliation
`glaucoma.
`
`(Fig. 11). As a refinement of the single-handed aspiration
`technique, which is easy and safe to use in combination
`with lens extraction, we now recommend the bimanual
`technique, in which irrigation and aspiration are
`separated from each other to further increase the safety
`and efficacy of the procedure (Fig. 12)?6
`The opening of the trabecular aspirator is 400 /-Lm
`wide and angled horizontally at 45° to comply with the
`configuration of the anterior chamber angle. The
`intracameral portion of the aspiration cannula is convex
`to prevent damage to the iris-lens diaphragm during the
`intraocular manoeuvre. For irrigation, a second cannula
`with an outlet diameter of 650 /-Lm is used. The surgical
`procedure is performed under the operating microscope
`without the use of a gonioscope. lntracameral access is
`gained by two self-sealing paracenteses at the limbus.
`The aspirator probe is pushed transcamerally into the
`opposite chamber angle and is directed against the
`trabeculum. Under gentle instrument-tissue contact,
`suction pressure of 100 and 200 mmHg is applied over
`4 to 5 dock-hours of the inferior and temporal
`circumference of the chamber angle. Thereafter,
`irrigation and aspiration probes are exchanged between
`hands so that the contralateral side of the chamber angle
`is accessible for aspiration treatment. Switching probes
`yields a potential treatment area of 270°.
`
`Fig. 12. Artist's rendering of the intraoperative view of the bimanual
`technique of trabecular aspiration. The aspirator is pushed deep into the
`anterior chamber angle, while the irrigation probe just enters the eye.
`Note the convexity of the aspirator's intraocular arm. Under constant
`tissue contact and negative suction pressure, the aspirator sweeps over
`the trabecular meshwork.
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`

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`The safety and efficacy of the bimanual technique of
`trabecular aspiration as a primary antiglaucoma surgical
`procedure was substantiated in a prospective study?6
`Twenty-two eyes of 18 PEX patients were treated by
`trabecular aspiration. Follow-up was continued for a
`minimum of 14 months and a maximum of 27 months
`(mean ± SD, 20.2 ± 4.5 months). The mean pretreatment
`lOP was 31.4 ± 7.1 mmHg (range 23-42 mmHg).
`Bimanual trabecular aspiration resulted in a consistent
`pressure reduction from the first post-operative week in
`19 eyes (86%). In the remaining 3 eyes (12.5%), trabecular
`aspiration neither reduced the lOP nor had any positive
`effect on the glaucoma medication post-operatively. Most
`interestingly, all these patients had had argon laser
`trabeculoplasty (AL T) prior to the aspiration procedure.
`With regard to the successfully treated eyes (n = 19),
`the mean pressure reduction after surgery was
`12.6 ± 0.7 mmHg (range 6-22 mmHg) at the final visit.
`At 6 months, the mean reduction in lOP from baseline
`was 12.5 mmHg. The mean reduction was 12.7 mmHg at
`1 year and 13.6 mmHg at 18 months. Before surgery,
`these 19 treated eyes required 2.3 glaucoma medications
`on average to control lOP. Post-operatively, the average
`number of medications was 0.3 at 6 months and 1.5 at
`18 months. At 6 months, 75% of patients were using no
`medication, and at 18 months 45% of patients were well
`controlled without glaucoma medication.
`Trabecular aspiration was not associated with any
`serious intraoperative complications or long-lasting side­
`effects. In 10 eyes (47%) a blood reflux from Schlemm's
`canal was observed intraoperatively, with 3 eyes (14%)
`showing small blot clots in the chamber angle post­
`operatively. However, no anterior chamber angle
`bleeding, hyphaema or marked inflammatory reaction
`was noted. In 4 eyes (19%), minor descemetolyses at the
`treatment site occurred. No corneal haze was associated
`with the treatment, and no episodes of hypotony,
`flattened anterior chamber depth or choroidal effusion
`were observed.
`The clinical importance of PEX syndrome lies in its
`reported association with open-angle glaucoma and age­
`related lens opacities.37-39 PEX syndrome as such does
`not induce optic nerve head damage but presents a
`relevant risk factor for lOP elevation.4o Various studies
`suggest that optic nerve head damage, visual field
`defects, higher lOP levels and reduced lOP tolerance are
`far more severe in glaucomatous eyes complicated with
`PEX than in those without PEX.41-43 Moreover, PEX eyes
`show a weaker response to medical therapy; thus, many
`of these eyes require early surgery.44 Besides, cataracts
`are more likely and their surgical correction more
`problematic in PEX syndrome than in non-PEX patients.
`Reported intraoperative difficulties include increased
`corneo-endothelial and iris pigment epithelial fragility,
`increased vascular leakage and inflammation, fibrin
`deposition, zonular instability often associated with
`zonular dialysis and vitreous 10ss.45-49 Post-operative
`problems may include an increased risk of synechia
`formation and pupillary block, rapid development of
`capsular thickening requiring laser capsulotomy, cystoid
`
`macular oedema in the presence of capsular trauma
`resulting in vitreous loss, transient lOP spikes, and
`progression of glaucoma optic neuropathy.48,49
`Consequently, PEX glaucoma coexisting with cataract
`poses a management dilemma. On the one hand,
`considering the potential intraoperative and post­
`operative complications in exfoliative eyes it would seem
`better to avoid or minimise perioperative problems by
`keeping the surgical procedure as simple as possible, Le.
`favouring a two-stage approach rather than a combined
`operation. On the other hand, a combined approach
`eliminates extra morbidity and costs, reduces the risk of
`transient post-operative pressure spikes, and may result
`in faster rehabilitation.
`In a recent study,50 we compared a randomised series
`of combined phacoemulsification, IOL implantation and
`trabecular aspiration (asp+ IOL) with a series of
`phacoemulsification and IOL implantation alone
`(IOL-alone). Performing the cataract incision temporally
`reduced the development of against-the-rule astigmatism
`and spared the superotemporal conjunctiva in both
`groups, making subsequent filtering procedures easier to
`perform. Trabecular-aspiration-treated eyes were also
`compared with a case-matched group that had
`undergone a standard glaucoma triple procedure (triple
`procedure). With the combined cataract and filtering
`approach, a temporal clear corneal incision also reduces
`inflammation around the filter, increasing the chances of
`a successful glaucoma procedure. We evaluated the
`impact of the two different approaches (Le. filtering
`versus non-filtering approach) in glaucoma triple
`procedure on post-operative visual acuity, the efficacy of
`the glaucoma procedure in reducing lOP and
`dependence on glaucoma medication, and complications
`experienced. Further evaluation of the efficacy of
`combined cataract and glaucoma surgery should
`enhance the surgeon's ability to make an informed choice
`for each cataract patient with PEX.
`The study group consisted of 74 eyes of 74 cataract
`patients with concurrent PEX glaucoma undergoing
`phacoemulsification with IOL implantation. Forty-eight
`consecutive patients were randomised to either
`adjunctive trabecular aspiration (asp+IOL group, 26
`eyes) or no trabecular aspiration (IOL-alone group; 22
`eyes). All patients who fulfilled the inclusion criteria