A C T A O P H T H A L M O L O G I C A
`61 (1983) 714-727
`
`Depadment of Ophthalmology (Head: A. Sokol),
`Sentralsjukehwet i Rogaland, Stavanger, Nomay
`
`SELECTIVE TRABECULECTOMY.
`A REPORT OF A NEW SURGICAL METHOD
`FOR OPEN ANGLE GMUCOMA
`
`BY
`
`FINN SKJERPE
`
`A new instrument, the trabeculectome, and an new surgical method for
`treating open angle glaucoma is described. The double-edged instrument
`makes 2 cuts through the trabecular meshwork while being pulled through
`Schlemm’s canal, thus cutting free a strip of the trabecular meshwork and the
`inner wall of Schlemm’s canal. The results of the 21 first operations are
`presented. The observation time is 9- 19 months. The characteristic post-
`operative pressure pattern is an immediate fall to 10-20 mmHg followed by a
`period of higher pressures which then converge to the range of 8- 16 mmHg
`with most eyes in the 10-14 mmHg range. Four patients need timolol
`treatment to obtain this, the remaining 17 have no medication. The thera-
`peutic results and additional observations are discussed with special interest to
`possible physiological mechanisms.
`
`Kq words: open angle glaucoma - trabecular meshwork - selective
`trabeculectomy - aqueous humour outflow.
`
`The treatment of the chronic glaucomas has improved during the later decades as
`new pharmacological agents have enriched our therapeutic armament.
`There seems, however, to be a rising activity in the field of surgical treatment.
`This may be the result of a rising understanding of the problem of patient
`compliance and of the danger of being satisfied with an ‘acceptable’ pressure level
`
`Received on March 14th. 1983.
`
`714
`
`Petitioner - New World Medical
`Ex. 1014, p. 1 of 14
`
`

`

`Skjzrpe
`
`Selective Trabeculectomy
`
`Fig. I.
`Histologic section of the anterior chamber angle where trabeculotomy has been performed.
`Note the very narrow slit through the trabecular lamellae. One can easily imagine that such a
`slit may close by tissue contact and scarring (haematoxylin and eosin, X 80).
`
`in the advanced glaucoma. It may also be a compensatory activity as it may have
`been hoped that the new glaucoma agents would solve the problem.
`Most advances in the surgical treatment of glaucoma have been improvements in
`making fistulas by stabbing the eyeball in more and more sophisticated ways, as in
`the different modifications of the so-called trabeculectomy, originally developed by
`Cairns (1968). But still these methods are mostly fistulizing in effect, as shown by
`Benedikt (1976) using a fluorescein technique investigating the aqueous outflow in
`normal eyes and in operated and non-operated glaucoma eyes.
`The various methods of trabeculotomy represent attempts to re-establish the
`normal drainage of the aqueous humour. Some years ago I performed trabe-
`culotomy in post-mortem eyes, removed a large corneal button and examined the
`chamber angle structures directly under the microscope. In some cases the
`trabeculotome created a flap hinged along the scleral spur. When the instrument
`was withdrawn, the flap fell back to its original position. This happened as a result
`of the elasticity of the trabecular tissue because there was no pressure gradient
`working on the flap. Even after trabeculotomy through the trabecular meshwork,
`tissue strands from the 2 sides of the slit may be brought in contact by the tissue
`elasticity and the intraocular pressure (Fig. 1). Fibrous bridges may form to close
`the slit totally or partially (personal investigation, not published).
`I have assumed that the reason why many trabeculotomies do not result in a
`desired or expected pressure level, is such a partial or total closure of the trabecular
`slit created.
`This paper presents a new instrument and a new surgical technique for the
`selective removal of the trabecular meshwork including the inner wall of Schlemm’s
`
`715
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`Petitioner - New World Medical
`Ex. 1014, p. 2 of 14
`
`

`

`Skjzrpe
`
`Selective Trabeculectorny
`
`canal through about 1/4 of its circle in order to obtain a free access for the aqueous
`humour into the collector canals. The method is built on the nylon filament probing
`technique of Smith (1962).
`
`Material and Methods
`
`The instrument
`The trabeculectome (patent pend.), a disposable instrument, is composed of a
`ring-like sharply edged cutting device attached to a flexible probe (Fig. 2). The
`edges emerging from the probe form an angle to fit to the scleral groove. The
`instrument has been under continuous development with different designs of the
`cutting parts used. All prototypes used in the first series of operations to be
`presented here, have had cutting edges made of steel attached to a 5-0 nylon
`monofilament.
`
`The working principle
`The free, blunt end of the probe is put through the canal of Schlemm over a sector
`of about 90". The cutting part is put into the anterior chamber and pulled by the
`
`Fig. 2.
`The trabeculectome. The cutting device is attached to a 0.15 mm thick flexible probe. The
`V-shaped cutting profile has in principle been the construction of the different prototype
`modifications used.
`
`716
`
`Petitioner - New World Medical
`Ex. 1014, p. 3 of 14
`
`

`

`Skjserpe
`
`Selective Trabeculectomy
`
`Fig. 3.
`Composite cross section and gonioscopic view showing the traheculectome cutting free and
`collecting a strip of the trahecular meshwork. It leaves an opened Schlemm’s canal.
`
`probe part with the edges protruding into the anterior chamber (Fig. 3). The edges
`in this way make 2 cuts through the trabecular meshwork, one along the scleral
`spur, and the other along the line of Schwalbe. The trabeculectome thus cuts free a
`strip of the trabecular meshwork including the inner wall of Schlemm’s canal, an it
`may remove the strip like a biopsy, leaving the outer wall and the openings of the
`draining canals.
`This technique has been worked out in post-mortem eyes, and the eyes have been
`examined microscopically. Fig. 4 shows cuts through the chamber angle of a
`
`Fig. 4.
`Histologic sections of the anterior chamber angle in a post-mortem eye, a) through a normal,
`unoperated sector and h) through a sector where selective traheculectomy has been
`performed. The trahecular meshwork which has been cut free, hut in this case not removed
`from the eye, is seen in the chamber angle. (haematoxylin and eosin, x 80).
`
`717
`
`Petitioner - New World Medical
`Ex. 1014, p. 4 of 14
`
`

`

`Skjaerpe
`
`Selective Trabeculectomy
`
`Fzg. 5.
`a) A radial incision through the deep scleral layers and the outer wall of Schlemm’s canal is
`made under a thick scleral flap. The inserted probe part of the trabeculectome is picked up
`through an angulated limbal incision about 10 mm from the first. b) Photograph shows the
`probe running through Schlemm’s canal between the two incisions.
`
`post-mortem eye, both through a not operated sector and through a sector where
`selective trabeculectomy has been performed. In these examinations no damage to
`any other intraocular structure than the trabecular meshwork and Schlemm’s canal
`was detected.
`
`The surgical procedure
`Schlemm’s canal is opened through a radial incision under a thick scleral flap,
`taking care not to cut through the inner wall and the trabecular meshwork (Fig. 5).
`The rounded probe end of the trabeculectome is inserted into the canal, clockwise
`or counterclockwise, and picked up through a new incision about 10 mm from the
`first. This second incision is angulated to make the opening big enough to let
`through the cutting part of the trabeculectome after the cut has been completed.
`The cutting part is brought into position under the scleral flap either by pushing or
`by pulling the probe through Schlemm’s canal.
`A triangular microflap is then performed at the insertion site under the scleral
`flap, making an opening big enough to allow the cutting part to be rotated and
`
`718
`
`Petitioner - New World Medical
`Ex. 1014, p. 5 of 14
`
`

`

`Skjwpe
`
`Selective Trabeculectomy
`
`Fig. 6.
`A triangular flap is made at the insertion site to allow the cutting device to be a) put into the
`anterior chamber and b) rotated against the scleral spur and pulled into position.
`
`pushed into the anterior chamber (Fig. 6). The microflap may be closed with a
`10-0 nylon suture, and the scleral flap is closed with 6-8 interrupted 10-0 nylon
`sutures taking care to secure a watertight wound. In order to avoid instrumental
`damage to the iris, the anterior chamber is, prior to the pull, filled with air in order
`to press the iris backwards. This injection is made through a separate corneal
`incision.
`The instrument is then pulled along Schlemm’s canal while twisting the probe
`slightly to press the posterior edge against the scleral spur. A slight rasping
`resistance is felt. The globe should be fixed with a toothed forceps at the edge of the
`scleral flap.
`A trabecular strip may follow the instrument out of the eye, or it may lie in the
`opening. Any strip is cut at the canal level. A periferal iridotomy or iridectomy is
`performed. A watertight closure is made at the pull out opening using 3 inter-
`rupted 10-0 nylon sutures, an the conjunctiva is pulled over with 1 stitch. Care is
`taken to leave the conjunctiva between the 2 incisions undisturbed to keep the
`water-veins undamaged.
`
`Post-operative treatment
`All patients have been given chloramphenicol and dexamethasone drops post-
`operatively and all pre-operative glaucoma treatment has been discontinued. The
`anit-inflammatory treatment has been given for as long as 1-2 months. However,
`because of a low grade and shortlasting post-operative reaction this treatment has
`
`719
`
`Petitioner - New World Medical
`Ex. 1014, p. 6 of 14
`
`

`

`Skjmpe
`
`Selective Trabeculectorny
`
`now been cut down to 1 or a few weeks duration. The first 5 patients were given
`oculoguttae atropini, but the following patients have been given shortacting
`mydriatics in case of suspected formation of posterior synechiae. Patients with a
`pre-operative shallow anterior chamber have been given pilocarpin intermittently
`when judged necessary in order to reduce the risk of goniosynechiae formation.
`
`Material
`23 eyes in 23 patients have been operated. 12 eyes had Glaucoma simplex (primary
`open angle glaucoma). 7 eyes had Glaucoma capsulare. 4 eyes had Glaucoma
`(1 posttraumatic, 2 postiridocyclitic and
`secundarium angulo aperto
`1
`haemorrhagic postrombotic glaucoma). 1 1 patients are women. 12 patients are
`men. Mean age: 74.8 years.
`All eyes have pre-operatively had maximal tolerable medical therapy and most
`patients had far advanced glaucomas with as long as 14 years treatment.
`19 eyes have been operated in an upper sector between the 10 or 1 1 o’clock and
`the 1 or 2 o’clock positions, and 2 eyes have been operated in a mid-nasal quadrant.
`4 eyes had 1-3 years previously undergone an ordinary fistulizing trabeculec-
`tomy, and one of these eyes was aphakic.
`The observation time in this material is 9- 19 months.
`
`Results
`
`Selective trabeculectomy has been carried through in 2 1 of the 23 eyes. In 2 eyes the
`operation could not be completed as intended, but was terminated as an ordinary
`fistulizing trabeculectomy. In one eye the cause was the inability to find Schlemm’s
`canal in a longstanding haemorrhagic glaucoma with fibrotic changes of the
`trabecular meshwork. In the other case the canal was found impossible to probe for
`more than 2 mm. At that time I had trabeculectomes made only for clockwise pull,
`and consequently the operation could not be continued by probing the canal in the
`opposite direction.
`In 8 patients a trabecular strip has been obtained and verified microscopically. In
`the remaining 13 patients only small strands or no trabecular tissue was obtained.
`Where the trabecular strip has been removed, there is a gonioscopically visible
`groove anterior to a thin, white line representing a naked scleral spur. In 2 of these
`cases where a strip is obtained, there is a thin sheet-like remnant with sparce
`pigmentation. It looks like the endothelial and corneal meshwork has been stripped
`off, and what remains looks like a sheet of the uveal meshwork.
`In the cases where a trabecular strip was not obtained, the trabecular meshwork
`
`720
`
`Petitioner - New World Medical
`Ex. 1014, p. 7 of 14
`
`

`

`Skjaerpe
`
`Selective Trabeculectomy
`
`is, gonioscopically seen, ploughed up and hinged along the scleral spur creating a
`slitlike or broad opening to Schlemm’s canal. The scleral spur is, also in most of
`these cases, seen as a distinct white line. In 3 of the cases the trabecular flap has
`fallen back to its original position. These failures have been related to the use of a
`prototype modification not in use any more.
`In most cases where an opening to the canal of Schlemm is obtained, there is,
`during gonioscopy, a visible retrograde flow of blood seeping into the anterior
`chamber from red dots in the scleral groove. This phenomenon has been observed
`more than 1 year after the operation. I have never seen any sign of blood seeping
`into the anterior chamber except during gonioscopy and in 2 cases spontaneously in
`the immediate postoperative period (first post-operative day).
`Changes are seen in the episcleral venous vessels in most cases. One finding is a
`dilution of the blood running through the episcleral venous plexus with a high flow
`
`120
`4 10
`i
`
`~
`
`30
`-
`A
`,-a
`20
`I
`-
`
`-
`
`10
`r
`0 )
`E -
`E
`
`1
`
`I
`
`Trabecular strip not obtained
`
`1
`
`,
`
`1
`
`1
`
`1
`
`1
`
`,
`
`1
`
`
`
`~
`
`l
`
`,
`
`,
`
`l
`
`l
`
`l
`
`l
`
`I2O 0 01 10
`] E l
`4 1 2
`n = l l
`
`l
`
`l
`
`360 420
`
`Fig. 7.
`Standard deviation curves (Mean ? 1 SD) and median values for the post-operative
`intraocular pressures in the group where a trabecular strip has been removed, are compared
`with the curves for the group where a trabecular strip has not been obtained. The separately
`plotted curve represents a patient with postoperative goniosynechiae to the operated sector.
`
`Acta ophthal. 61, 4
`
`46
`
`72 1
`
`Petitioner - New World Medical
`Ex. 1014, p. 8 of 14
`
`

`

`Skjmpe
`
`Selective Trabeculectorny
`
`velocity. However, the most conspicuous observation is the appearance of
`waterveins with a broad clear fluid laminar flow which has also a very high velocity.
`Especially where small veins empty into a scleral perforant aqueous vein carrying
`clear fluid, I have seen pronounced pulsations of the flow of blood from these veins
`into the aqueous-filled bigger vessel. These pulsations are synchronous with the
`patient’s arterial pulse rate. These perilimbal findings have been most prominent
`when the operation has been performed to cover some part of the mid-nasal sector.
`In one case there is also a pronounced flow of aqueous humour through
`water-veins far away from the operated sector.
`The intraocular pressure has, as far as possible, been measured daily from the
`first post-operative day with a Goldmann applanation tonometer for 1-2 weeks
`followed by frequenty controls.
`Standard deviation curves and plotted median pressure values clearly show the
`pressure pattern in the immediate postoperative period and the end result. (Figs.
`7-8).
`After the successful removal of a trabecular strip the characteristic and rather
`constant post-operative pressure pattern is an immediate fall to the range of
`10-20 mmHg followed by a rise after about 1 week, in some cases with a need for
`temporary medical treatment (Fig. 7). In these cases timolol and acetazolamide have
`a striking pressure lowering effect. After 4-8 weeks the pressures level off, in most
`cases to 8- 14 mmHg, and the medication, if any, is discontinued. In the group
`where a strip of the trabecular meshwork is not obtained, the pattern is in principle
`the same, but there is a slightly prolonged period of unstable and high pressures. In
`the cases where the operation covers a substantial part of the nasal sector, the
`intraocular pressure seems to fall to the final level more rapidly and with a less
`pronounced high pressure period than in the other cases.
`Seven patients with a conjunctival bleb are compared with the 14 without any sign
`of a fistula. The statistical curves in principle show the same pressure pattern in
`both groups with a convergence of the pressures towards the range of
`8- 16 mmHg, as in the former groups (Fig. 8).
`Of the 21 patients operated only 4 need post-operative treatment in order to
`reach the pressure level described above. In all 4 cases timo!ol alone is sufficient to
`obtain this. One of these 4 patients also needs acetazolamide for the other, not
`operated eye. One other patient with goniosynechiae to the operated sector and
`with no sign of fistulation has had post-operative treatment with epinephrine and
`acetazolamide for 13 months (timolol not tolerated because of asthma). With this
`treatment the eye has had a pressure of 18-22 mmHg. Pilocarpine was the
`prescribed, but the patient discontinued this after 1 day because of a pain-reaction.
`At the control 3 weeks afterwards the intraocular pressure had fallen to
`12 mmHg. At the same time a water-vein has was at one end of the operated sector.
`
`722
`
`Petitioner - New World Medical
`Ex. 1014, p. 9 of 14
`
`

`

`Skjaerpe
`
`::I
`
`30
`
`Selective Trabecu lectorny
`
`Visible conjunctival bleb
`
`I
`0
`
`E
`E
`
`l
`I
`I
`
`~
`
`-
`
`1
`1
`1
`dp. I0
`
`
`
`,
`
`-
`
`n=7
`
`1
`
`
`
`-
`
`I
`30
`
`50
`
`70
`
`YO
`
`1
`
`-
`
`
`
`110
`
`.--
`
`1 420
`
`Fig. 8.
`1 SD) and median values for the post-operative
`Standard deviation curves (Mean
`intraocular pressures in the group with a post-operative conjunctival bleb are compared with
`the curves for the group without any sign of a fistula. The separately plotted curve represents
`a patient with post-operative goniosynechiae to the operated sector.
`
`The medication with epinephrine has been discontinued (acetazolamide is needed
`for the other eye), and the pressure has stablized at about 14 mmHg. Because this
`patient represents an important type of complication and also shows an interesting
`course, these pressures are not taken into the statistic curves from about the 4th
`post-operative month, but are plotted separately to show the peculiar course in this
`patient (Figs 7 and 8).
`No deterioration of the visual fields has been registered during the observation
`time, except in 1 case where the change in a defect of the visual field had to be
`compared with a registration made 2 months pre-operatively.
`The complications have been as follows:
`
`Bleeding
`In 4 cases per-operative bleeding caused a post-operative hyphaema filling 1/4 of
`the anterior chamber. In 11 cases there has been a hyphaema 1 - 1.5 mmHg high.
`
`723
`
`46%
`
`Petitioner - New World Medical
`Ex. 1014, p. 10 of 14
`
`

`

`Skjmpe
`
`Selective Trabeculectomy
`
`In the remaining 6 cases no bleeding has been seen except for some cells seen with
`the slit lamp, and a thin sheet of blood in the inferior chamber angle seen with a
`goniolens. All hyphaemas have disappeared in 1-4 weeks.
`
`Inflammation
`The inflammatory reaction has been slight with a minimal to moderate short-lasting
`flare except in 1 post-inflammatory and 1 post-traumatic glaucoma where a
`pre-existing flare has continued after the operation.
`
`Goniosynechia
`In 1 case peripheral goniosynechiae have developed in the operated sector. The
`peripheral iris covers the groove where the trabecular meshwork has been
`removed.
`
`Cataract
`In 1 case of glaucoma with a pre-operatively existing iridocyclitis there has been a
`progressive development of a posterior cataract. In 1 case a pre-operatively
`progressing senile cataract continued to progress post-operatively. In no other case
`has it been possible to detect a reduced visual acuity or any change in any existing
`cataract.
`
`Fistula
`In 7 cases a subconjunctival filtration bleb developed after 2-3 months. These blebs
`have vaned from ordinarily sized filtration blebs, as obtained after fistulizing
`procedures, to an almost invisible bleb-like formation at either of the incisions.
`Nothing has been done with these blebs except in one case in which the intraocular
`pressure fell to 6 mmHg. This fistula was closed surgically, and the intraocular
`pressure stabilized at 10- 12 mmHg which was also the pressure level before the
`fistula appeared. Four of these patients are among the first ones operated, and in
`these cases the wounds were closed with a braided suture (Dexon).
`
`Discussion
`
`The post-operative pressure pattern after selective trabeculectomy strongly indi-
`cates that the reduction of the intraocular pressure is caused by a restored flow of
`the aqueous humour through the collector canals into the water-veins. This
`statement is founded on the fact that the pressures seldom fall below a barrier of
`
`724
`
`Petitioner - New World Medical
`Ex. 1014, p. 11 of 14
`
`

`

`Skjzrpe
`
`Selective Trabeculectorny
`
`about 8 mmHg and seem to converge to a level not high above this barrier. This is
`consistent with our concept of the eye as a one way pump system with a recipient
`pressure for the aqueous humour in the episcleral veins of 6-8 mmHg. In such a
`system the intraocular pressure has to build up to exceed this counterpressure with
`an addition for the flow restistance through the collector canals.
`Initial high pressures in a few cases have possibly been caused by a visible blood
`clot in the anterior chamber angle of the operated sector.
`The existence of an opening for free fluid flow between the anterior chamber
`and the episcleral veins is proved by the observation of blood seeping in thin
`streams into the anterior chamber during gonioscopy. This communication seems
`to be the anatomic foundation of the pressure lowering effect of the operation.
`The main qualification for the low and stable pressures seems to be a ‘broad’ and
`permanent opening between the anterior chamber and Schlemm’s canal. This is
`supported by the observation that the pressure lowering effect seems to be related
`to the degree of visible opening to Schlemm’s canal because in the cases where there
`is a very narrow slit or a seemingly closed slit, the pressure is higher than in the
`‘broad-opening’ cases, and medical treatment may be necessary. The reason why
`the trabecular meshwork not removed in these cases seem to have less tendency to
`retain its original position compared with the trabeculotomy cases, may be a partial
`or subtotal cut through the trabecular tissue along the scleral spur.
`A second qualification is the number of the collector canals and the size of their
`ostia which have been made accessible for the aqueous humour. There is a potential
`circumferential flow through Schlemm’s canal. In one case there is a pronounced
`flow of aqueous humour through water-veins far outside the operated sector.
`However, one should not rely on the circumferential flow, because the openings of
`Schlemm’s canal at both ends of the operated sector may close by scarring. The
`findings of large water-veins, especially nasally, and even with signs of pulsating
`flow of the aqueous humour entering these veins, together with a seemingly more
`rapid stabilization of the intraocular pressure to its final level when the operation is
`performed to cover a substantial part of the nasal sector, indicate that the collector
`canals have their greatest draining capacity in the nasal quadrants. This is most
`interesting when compared with the findings of Benedikt (1976) that the water-
`veins are most numerous and even of greater caliber in the 2 nasal quadrants.
`Therefore, it seems correct to perform the operation in a sector where the widest
`and most numerous draining canals are found, that is, as already pointed out,
`nasally.
`The pathogenesis of the post-operative period with high and unstable pressures
`is not proved. Most pressures rise after a delay of 4-10 days. A post-operative
`oedema should be most prominent during the first days after the operation, and it
`should not last as long as 1 or 2 months. A few days treatment with dexamethasone
`
`725
`
`Petitioner - New World Medical
`Ex. 1014, p. 12 of 14
`
`

`

`Skjserpe
`
`Selective Trabeculectomy
`
`is expected to be sufficient to reduce such an oedema. Post-operative oedema
`therefore seems to be an unsatisfactory explanation of the temporarily elevated
`pressures.
`Johnston et al. (1979) have shown that the endothelial cells of the blood vessels in
`the limbal area in avian eyes are mesodermally derived. This means that the
`endothelium of Schlemm’s canal most likely is mesodermally derived, and therefore
`supposed to have the capacity of regeneration. This endothelium, damaged during
`the operation, will swell up to take a spheriod shape when multiplying. The ostia of
`the collector canals may in this way be obstructed during the endothelial repair.
`Such a swelling will of course affect the flow less where the ostia have their greatest
`diameter. A process like this, I think , is a probable explanation of the post-
`operative high pressure period.
`As a whole, by pulling the trabeculectome along Schlemm’s canal it is possible
`either to remove a strip of the trabecular meshwork including the inner wall of
`Schlemm’s canal, or to plough up the tissue so widely that it will seldom fall back to
`its original position. The operation seems to re-establish the normal drainage of the
`aqueous humour. The intraocular pressure is stabilized at a rather ideal, low level.
`Post-operative hypotension and a shallow anterior chamber is avoided. The
`operation is performed in a way that secures a retreat through an ordinary
`fistulizing trabeculectomy in case Schlemm’s canal is not found or is found
`impossible to probe. The results of 35 subsequent operations with factory made
`trabeculectomes have been similar to the results obtained in the 2 1 first patients.
`A new design of the cutting part is now under development. This cutter will be
`shaped to fit as completely as possible into the anatomical structures of the chamber
`
`Fig. 9.
`The new and improved trabeculectome is expected to be ready for production during the
`winter 1982/1983. Note that the cutting profile is shaped to fit into the scleral groove and
`around the scleral spur in order to secure an as perfect as possible removal of a trabecular
`strip in as high a percentage of the cases as possible.
`
`726
`
`Petitioner - New World Medical
`Ex. 1014, p. 13 of 14
`
`

`

`Skjwpe
`
`Selective Trabeculectomy
`
`angle (Fig. 9). it will hopefully facilitate a complete removal of a trabecular strip in a
`higher persentage than up to now. If a strip is not removed, the cutter will, because
`of its shape, plough up the tissue so widely that it is not expected to fall back again to
`close the opening once obtained. The cutting part will be moulded in very hard
`plastic, a technique suitable for mass production. The trabeculectome is a
`disposable instrument. Because of its assymmetry, it will be made in 2 versions, one
`for clockwise and the other for counter-clockwise pull. Before the instrument
`comes onto the market, samples for the interested surgeon may be available by
`request to the author.
`
`Acknowledgments
`
`This work has in part been supported by Sigval Bergesen & Co. DY. (Sig. Bergesen & hustru
`Nanki’s alrnennyttige Stiftelse), and Elf Aquitaine Norge AIS.
`
`References
`
`Benedikt 0 (1976): Die Darstellung des Kammerwasserabflusses normaler und glaucom-
`kranker menschlicher Augen durch Fulling der Vorderkammer mit Fluorescein. Albert
`von Graefes Arch Klin Ophthalrnol 199: 45-67.
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`66: 673.
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`
`Author’s address:
`Finn Skjzrpe, M.D., Department of Ophthalmology,
`Sentralsjukehuset i Rogaland, N-4000 Stavanger, Norway.
`
`727
`
`Petitioner - New World Medical
`Ex. 1014, p. 14 of 14
`
`