RELATIONSHIP OF BASAL IRIDECTOMY TO SHALLOW CHAMBER FOLLOWING EXTRACTION

BY Kenneth C. Swan, M.D.*

A STUDY CONDUCTED at the University of Oregon Medical School since 1950 revealed that shallowing of the anterior chamber after cataract extraction was an uncommon, but sometimes serious, complication which developed under several circumstances. In patients observed prior to 1951, the anterior chamber occasionally did not reform during the first twenty-four hours after surgery. In those a wound leak usually was demonstrable. In 1951, we began to use a limbus-based flap of conjunctiva and Tenon's capsule to bury a half-lap type of limbal incision which had been closed with multiple catgut sutures (Figure 1). This technique virtually eliminated failure of reformation of the anterior chamber and epithelial ingrowth,' but it did not prevent a second type of shallow chamber which most commonly developed without a demonstrable wound leak seven to twenty-one days postoperatively. In 1957, Weisel and 12 described what we thought were the important clinical features of this second type of shallow anterior chamber (Table 1). It was associated with hypotony, choroidal separation, posterior vitreous detachment with forward dis- placement, and adherence of an intact vitreous face to the pupil and opening. The resultant vitreous obstruction to the flow of aqueous from the posterior into the anterior chamber contributed to the shallow chamber. This viewpoint was not widely accepted because the prevalent concept then was that pupillary obstruction would have to be associated with elevated tension. We felt that, in those eyes, there was hypotony, rather than , because the formation of aqueous wvas decreased. Chandler and Maumenee have provided evidence to stupport this concept.:' *Froimi the Tolhn E Weeks Inistittute of , University of Oregon Medical School. TR. AM. OP1ITH. Soc., vol. 60, 1962 214 Kenneth C. Swan

FIGURE 1 The half-lap type of limbal incision is begun perpendicular to the surface at the junction of opaque sclera and translucent limbal stroma. Halfway through the stroma, it is split forward and then extended to enter the anterior chamber near Schwalbe's line. The limbal incision is closed by multiple absorbable sutures buried under a limbus-based flap.

TABLE 1. MAJOR TYPES OF SHALLOW CHAMBER AFTER CATARACT EXTRACTION

(1) Delayed reformation-wound leak generally demonstrable (2) Late shallowing of chamber (4-21 days) wound leak seldom demonstrable (a) Onset 4-21 days after surgery (b) Gross detachment of choroid and ciliary body (c) Hypotony (d) Forward displacement of intact vitreous face with obstruction of pupil and iris coloboma

In some, but not all, of our cases of late shallow chamber without demonstrable wound leak, the anterior chamber reformed spon- taneously, a phenomenon which could not be depended upon, but which made the evaluation of therapy difficult. We did find that intensive use of mydriatics sometimes alternated with miotics generally restored the anterior chamber if initiated before adherence of the Shallow Chamber Following Cataract Extraction 215

FIGURE 2 Stereophotographs illustrating mydriatic treatment of shallow chamber with vitreous obstruction, hypotony, and choroidal detachment of three days' duration (top). The chamber has begun to deepen after 40 minutes (middle) and is deep with maximal mydriasis at 90 minutes (bottom). vitreous face to the iris became too firm. The effectiveness of this procedure has been confirmed by Chandler.4 In this (Figure 2), photographed twelve days after a seemingly uncomplicated intra- capsular extraction, a shallow chamber developed and persisted for three days. The anterior chamber reformed within ninety minutes after the topical administration of single drops of 1 per cent atropine sulfate, 5 per cent cocaine, and 1 per cent epinephrine bitartrate. Another non-sturgical measure was effective in some neglected caises; this was to rupture pupillary adhesions to the vitreous face by gentle point pressuire applied to the iris through the anesthetized . The maneuver was performed at the slit-lamp biomicroscope, 216 Kenneth C. Swait or with the operating microscope, if the patient was lying down be- cause magnification was desirable for visual control and observation of the results. Only topical anesthesia was required and no speculum was necessary. The lubricated tip of a glass rod was placed on the cornea midway between the pupillary margin and the limbus (Figure 3). Only gentle pressure indented the cornea and iris in those soft eyes. Often pupillary adhesions were seen to separate and the anterior chamber to reform within two to three minutes. NMy colleagues and I did not use the technique until at least eight days postoperatively, but noted no wound separations or other ill effects from the manetver.

FIGURE 3. IECHANICAL RIUPTURE OF IRIS ADHESIONS TO VITREOUS AT THE PUPILLARY MARGIN. With topical anesthesia the cornea aind underlyillg iris arc ectly indented witlh thc lubricated tip of al glass ro(l.

Shallow chamber associated wvith vitreotus block, lhypotoni, and choroidal detachment often is aI precursor to aphakic glaucoma associated with vitreous herniation and pupillarv obstruction. There- fore, it seemed logical to treat this type of shallow chamber along the same principles; that is, in both conditions, attempts were made to relieve the vitreous obstruction of the pupil and iris coloboma. (Table 2). If the anterior chamber could not be reformed by drugs or massage through the cornea, peripheral iridectomy was performed in the inferior temporal quadrant (Figure 4), rather tlhain wait Unltil extensive peripheral adlhesions or vitreous block glaucoma had de- veloped!5 Without evidence of continuous external leakage of aqueous, I did not deem it necessary to open the conjunctival and Tenon's Shallow Chamber Following Cataract Extraction 217

TABLE 2. ORDER OF TREATMENT OF SHALLOW CHAMBER WITHOUT DEMONSTRABLE WOUND LEAK

(1) Medical Intensive mydriatic therapy sometimes alternated with miotics to mobilize the pupil (2) Mechanical Point pressure on iris throuLgh cornea to mechanically disrupt iris adhesions to vitreous face (3) Surgical 1. Peripheral iridectomy 2. Other surgical procedures, rupture vitreous face, sclerotomy

FIGURE 4. INFERIOR TEMPORAL IRIDECTOMY FOR RELIEF OF VITREOUS OBSTRUCTION OF PUPIL AND OPERATIVE COLOBOMA. incision and explore the limbal wound. In our cases, leakage of aqueous under the conjunctiva did not appear significant. Robert Cowger and 16 reviewed our cases of unintentional filtrations which developed after cataract extraction (Figure 5). No correlation could be found between the occurrence of filtrations and shallow chambers. I reviewed over 3,000 cataract extractions which were performed on the services at the University of Oregon Medical School in the period from 1951 through 1961. During that period, peripheral iridectomy was performed on six eyes with postoperative shallow chambers associated with hypotony; three of these patients had not kept out- patient appointments after their discharge from the hospital and, 218 Kenneth C. Swan

FIGURE 5. UNINTENTIONAL FILTRATION WHICH DEVELOPED AFTER CATARACT EXTRACTION. No correlation could be found between the occurrence of this type of filtration and the incidence of postoperative shallow chamber. therefore, were not under control of the attending physicians for periods which allowed firm adhesions to develop between the vitreous face and iris. A fourth patient had a low grade uveitis and the fifth and sixth patients had had small hyphemias. Posterior synechias made it impossible for us to mobilize the pupil by non-surgical means. In all six eyes, lasting restoration of the anterior chamber was obtained by iridectomy alone. In addition, iridotomy was performed through limbal puncture wounds on two other eyes with shallow chambers, choroidal detachment, and hypotony. One of the iridotomies closed with recurrence of the shallow chamber, but a subsequent peripheral iridectomy was effective. In summary, restoration of the anterior chamber was obtained by iridectomy or iridotomy in all eight eyes without resorting to air injections, rupture of the vitreous, sclerotomy, or resuturing of the limbal wound. Two other patients were not in- cluded in this series because the surgeons ruptured the vitreous face when they attempted to separate the pupillary margins from the vitreous with a spatula. The chamber was restored in these cases; Shallow Chamber Followving Cataract Extraction 219 however, in one, there was bleeding into the vitreous with resultant reduction in visual acuity due to residual vitreous opacities and, in the other, the cosmetic result was poor due to tearing of the peri- pheral iris. As a result of these experiences coupled with the demon- strated effectiveness of iridectomy alone, attempts to free the pupil from the vitreous face were considered unnecessary and apt to add complications. During the same period from 1951 through 1961, there were observed on our services only six eyes with glaucoma associated with obstruction of the primary aqueous circulation by clear vitreous. Cases of pupillary obstruction due to organized hemorrhage, inflam- matory membranes, or remnants were not included in this series, although a number were observed. This relatively low incidence of vitreous block glaucoma verified Chandler's belief that this type of glaucoma was largely preventable. In addition to the six cases from our services, two other patients were referred for care by other sur- geons. Of the eight patients, three had had round pupil extractions with peripheral iridectomy; one had had a round pupil extraction with iridotomy; and the three others had had what were thought to be complete iridectomies, but the openings did not extend to the root of the iris. The eighth case had a radial iridotomy which did not extend to the base of the iris (Figure 6). In all eight, the iris colobomas as well as the pupils were obstructed by vitreous. The results of treatment of the eight cases of vitreous block glau- coma are summarized in Table 3. None responded to mydriatic therapy alone, but point pressure on the iris through the cornea was dramatically effective in one. In the other seven eyes, peripheral iridectomy was made. In five, the anterior chamber reformed promptly and lasting relief of the glaucoma was obtained without disruption of the vitreous face. In the sixth case, increased ocular tension and shallowing of the anterior chamber recurred within twenty-four hours. A second iridectomy with deliberate rupture of the vitreous face was successful. In the seventh case, the iridectomy was noted to become obstructed by vitreous, while the patient was still on the operating table. No appreciable deepening of the anterior chamber occurred in the ten to fifteen minutes after iridectomy and the remained relatively firm; therefore, the vitreous face was deliberately opened through the iridectomy. At first, viscid vitreous, and then watery fluid escaped. An anterior chamber developed promptly and the glaucoma was controlled. In the last two cases, I could not be certain whether the obstruction was at the point of contact of the vitreous 220 Kenneth C. Swan

FIGURE 6 Intracapstular cataract extraction with radial iridotomv 6 weeks after sturgery by resident physician (top, left). revealed that coloboma did not extend to periphery of the iris and vitreous was herniating into it (bottom). Actute vitreotus block glaucomiia developed two weeks later (top, right). witlh the iris, or by the vitreous face with posterior flow of aqueous, as postulated by Leonard Christensen and Robert Shaffer.7 These two cases, and observations that the iris coloboma as well as the pupil bad to be plugged by forward displacement of the vitreous face to pro- duce either shallow chamber with hypotony, or shallow chamber with glaucoma, led us to change our terminology from "pupillary block glaucoma" to the more accurate designation of "vitreous block glaucoma." I observed hundreds of eyes in which the pupil appeared Shallow Chamber Following Cataract Extraction2221 to be completely obstructed by the herniation of the intact vitreous face, but neither shallow chamber nor vitreous block glaucoma de- veloped as long as some part of the iris coloboma was open. This directed our attention to the relationship of the vitreous to the peri- pheral iris in .

TABLE 3. EIGHT CASES OF VITREOUS BLOCK GLAUCOMA

(1) None cured by mydriatics (2) One cured by mydriatics plus point pressure through cornea (3) Five cured by peripheral iridectomy (4) Two cured by peripheral iridectomy plus rupture of vitreouis face

Beginning in 1955, the position of the vitreous face in relation to the peripheral iris and the wound of entry into the eye was studied by slit-lamp biomicroscopy and gonioscopy in all aphakic eyes observed in our clinic. The anterior face of the vitreous generally was found to be quite convex with the apex in the pupillary area; therefore, ad- herence of the vitreous seldom occurred to incisions entering the globe at Schwalbe's line. In uncomplicated intracapsular extractions, hernia- tions of the intact vitreous face through the periphery of the iris colobomas seldom were seen provided that a relatively basal opening was present, but herniations through the pupil were found to be re- latively common. In the first months after intracapsular cataract extraction, the vitreous face, as observed with a gonioscope through the operative coloboma, seldom was in contact with the back surface of the peri- pheral one-third of the iris, but often was in contact with the iris in the pupillary area (Figure 7). This observation was confirmed by the study of aphakic eyes in the John E. Weeks Laboratory and in published microphotographs. In most eyes, the protrusion of ciliary processes into the eye make it impossible for the intact vitreous face to contact the extreme periphery of the iris; consequently, a posterior chamber usually persists in aphakic eyes (Figure 8). Persistence of a peripheral posterior chamber explains why it usually is possible to perform peripheral iridectomy in aphakic eyes without loss of vitreous; also, it seemed logical that in the conduct of an iris opening in the periphery would be less apt to be plugged by forward herniation of the vitreous than an opening placed close to the sphincter. Clinical observation proved this to be the case. What is the clinical importance of this anatomical fact? 222 Kenneth C. Swan

FIGURE 7 After uncomplicated cataract extraction the vitreous face is most prominent in the pupillary area and often herniates through it. In the periphery the vitreous usually is behind the level of the iris and not in contact with it.

FIGURE 8. PERSISTENCE OF POSTERIOR CHAMBER IN PERIPHERY OF APHAKIC EYE OBTAINED POST MORTEM. The ciliary body and processes prevent the vitreous from contacting the extreme periphery of the iris. Shallow Chamber Following Cataract Extraction 223 Last year, in a paper presented before this Society, Chandler ex- pressed the belief that vitreous block glaucoma was more common with round pupils than with complete iridectomy.4 John McLean did not agree. Gonioscopic studies conducted at Oregon may resolve this argument. No significant difference was found in the incidence of shallow chamber with later vitreous block glaucoma, in cases with peripheral versus complete iridectomy, provided that an adequate opening was obtained in the extreme periphery of the iris. Postoperative gonioscopy was performed in nearly 2,000 aphakic eyes; these studies revealed that in one out of every four cases operated by our resident staff what had been intended to be a com- plete iridectomy often did not extend to within one millimeter of the root of the iris; however, one out of three peripheral iridectomie3 was not basal. This higher incidence of inadequate openings in the periphery of the iris accounted for what at first seemed to be a higher incidence of shallow chambers developing after our round pupil extractions. The incidence of delayed shallow chamber (with evidence of vitreous b!ock and without demonstrable wound leak) was 5 per cent (29 out of 585 eyes), without an adequate peripheral iris opening, as compared to slightly less than 2 per cent (27 in 1412 eyes) in which the iris opening extended within one millimeter of the iris root (Table 4).

TABLE 4. INCIDENCE OF SHALLOW CHAMBER IN RELATION TO IRIS OPENING

5.1% without adequate basal opening (29 in 581 eyes) 1.9% with adequate basal opening (27 in 1412 eyes)

It was evident from the above described studies that an inadequate peripheral iris opening could not be the sole cause of shallow chamber due to vitreous obstruction, but actually was an important factor. There were noteworthy clinical examples which could be documented by photography. Figure 9 shows the eyes of a patient who developed a vitreous type block glaucoma six weeks after cataract extraction. The surgeon thought that he had performed a complete iridectomy, but it can be seen that the iridectomy did not extend to the base of the iris. Peripheral iridectomy inferiorly re- lieved the shallow chamber and glaucoma. Cataract extraction with a complete iridectomy extending to the root of the iris was performed on the other eye without complications. The eye of another patient who developed vitreous block glaucoma was photographed through 224 Kenneth C. Swan

'1%

:.., iii.s

FIGURE 9 Intracapsular cataract extraction O.D. (left) was followed by glaucoma. The initial iridectomy did not extend to the base of the iris and was blocked by vitreous. The glaucoma was cured by iridectomy in the inferior temporal periphery. Course of O.S. (right) was uncomplicated because the iridectomy extended peripheral to forward curve of vitreous face.

FIGURE 10 "Complete" iridectomy viewed through the front surface (center) of an Allen- Thorpe gonioscope appears adequate, but the lower mirror reveals that the iridectomy did not extend to the periphery. Shallow Chamber Following Cataract Extraction 225 an Allen-Thorpe gonioscope (Figure 10). In a direct view through the flat front surface of the lens, a complete iridectomy of adequate size appears to have been made, but it can be seen in the lower mirror that the iridectomy did not extend to the base of the iris. The intact vitreous face blocked both the pupil and the coloboma! An inferior peripheral iridectomy was effective. These clinical and anatomical studies led to a review of our tech- niques of iris openings in relation to the incision. On my services since 1951, all cataract operations have been performed with a half- lap type of incision (Figure 1), but some other members of the faculty have continued to use keratome and scissors. In both tech- niques, we observed that it was difficult to obtain an adequate peripheral opening in the iris if the incision entered the anterior chamber forward in the cornea; this was dramatically demonstrated in microscopic studies of the eye of a patient who died nine days after an intracapsular cataract extraction performed by a resident surgeon. At death, the patient had a shallow anterior chamber with choroidal

>'YVitreous face

FIGURE 11. POSTMIORTENM SPECIMEN OBTAINED 11 DAYS AFTER CATARACT EXTRAC- TION, COMPILICATEJ) B'Y SHALLOW CHAMBER, HYPOTONY, AND CHOROIDAL 1)ETACHMENT. Inicision entered the anterior chaimiber too far forward, and the iridectomy was not basal. Vitreous was adherent to edge of coloboma and pupil, with resultant obstruction of aqueous flow. Wound separated by trauma of enucleation. 226 Kentneth C. Swani detachment and forward herniation of the vitreous. A wound leak was not demonstrable clinically or by inspection of the wound post mortem. Unfortunately the half-lap incision was separated by the trauma of enucleation. As shown in Figure 11, the surgeon excised iris only back to the point of entry of the incision into the eye. As the incision entered the anterior chamber well forward in the cornea the iridectomy was not basal. Vitreous was adherent to the iris only near the edge of the pupillary margin and a posterior chamber was present. A more basal iridectomy in this eye would have been less likely to have been blocked by the vitreous face which was well away from the iris periphery. The importance of a basal iridectomy was illustrated in another eye enucleated with the vitreous block type of glaucoma (Figure 12). Again, it can be seen that a basal iridectomy had not been made. The vitreous was adherent only to the edge of the opera- tive coloboma. Again, a peripheral posterior chamber was present and the vitreous was well away from the periphery of the iris. In this eye also a more basal iridectomy would have had less chance to become obstructed.

FIGURE 12. VTITIkEOIJS BILO(CK CGIAUC(OMA RlSULTING FROAI INAI)EQUATF I Ff1 IP-IE Al, IBAIS OPENING. The vitreouLs was a(ldherent to the edges of the ptipil anid the colohoina, but at posterior chamber was preseint. The ciliary body aind processes might have prevented the vitreous from blocking a peripheral iris opening. Shallow Chalmalber Following Catar-act Exttaction 227 What lessons did we learn about the technique of iridectomy in cataract extraction? First, we learned that an incision entering the anterior chamber in the region of Schwalbe's line permitted an ade- quate opening to be made in the peripheral iris and that suich an incision was less apt to be obstructed by either iris or vitreous than a corneal incision. Figure 13 illustrates a patient with a corneal in- cision who was referred to me with vitreous block type of glaucoma. Both iris and vitreous were adherent to the corneal iincision. The iridectomy which relieved the glaucoma and shallow chamber canl be seen inferiorly. A new pupil was created later by photocoagulation. In the performance of a complete iridectomy, our resident staff has been instructed to grasp the iris just behind the sphincter, rather than at the sphincter, as is advised in many surgical textbooks. If the iris is grasped behind the sphincter, the peripheral iris is stretched into the wound and can be excised, whereas if the iris sphincter only is grasped, the peripheral iris is relaxed an(d may not be drawn into the incision. An inadequate peripheral opening may result as shown

FIGURE 13. ADHERENCE OF IRIS AND VITREOUS TO A CORNEAI. INCISION FOR CATARACT EXTRACTION. The smllall updrawn puipil lecallle obstructed by vitreous. The resultanlt ,l.4aucoma was cured by the peripheral iridectomy made inferiorly. 228 Kenneth C. Swan in Figure 10. I do not advocate tearing of iris (iridodialysis) because there is danger of inducing serious bleeding. Simple iridotomies are no longer performed intentionally on my services. The custom used by some surgeons of introducing the scissors' tips into the anterior chamber to snip the iris almost invariably leaves an opening which is relatively small and too far from the base of the iris (Figure 14). This is particularly apt to occur if the pupil has been widely dilated to facilitate delivery of the lens. To perform an adequate

FIGURE 14. UNDESIRABLE TYPE OF IRIDOTONIY RESULTS WHEN SCISSORS ARE INTROI)UCED INTO THE EYE AND THE IRIS IS SNIPPED WITHOUT THE USE OF FORCEPS. The opening is small and not in the periphery. It is apt to be plugged by the vitreous forward curve of the face. peripheral iridectomy, forceps should be used to grasp the extreme periphery of the iris. I have observed that radial iridotomies or sphincterotomies advocated by some surgeons to reduce the size of the coloboma are particularly apt to be plugged by vitreous because often the opening does not extend to the periphery of the iris (Figure 6). In this presentation, I have not touched on all aspects of shallowing of the anterior chamber; for example, I have not discussed the re- lationship of trauma, inflainmationi, clhoroidal lhemorrlhage, or a number of otlher possible factors predisposing to these conditions, such as structural abnormalities in the vitreous or causes of its forward displacement in some eves. Fuirthermore, I recognize that even in the Shallow; Chla ber Follow(ingf Cataract Extliction2229 surgical technique there are factors, other than iridectomny, suchli as exacting wound closures which are important. In this paper, my primary concern has been witlh the relationship of the oplening in the iris and placement of the incision in connection with obstruction by the intact vitreous face. Attention to this and other factors dis- cussed in this paper has reduced significantly the incidence of late shallowing of the anterior chamber following seemingly uncomplicated cataract extraction, on my services. For example, in 1957, W7eisel and 12 reported an incidence of 7 per cent (14 out of 200 cases). In a comparable series, observed in 1961 and 1962. I found an incidence of 2 per cent (4 out of 200 cases).

SUN1MARY A review of cases at the University of Oregon Mledical School re- vealed that failure of reformation of the anterior chamber after cataract extraction was virtually eliminated by the use of a limbus- based flap and a limbal incision carefully closed with buried sutures. However, late shallowing of the anterior chamber occurring with- out demonstrable wound leak and associated with choroidal detach- ment and hypotony still occurred in a few cases. Five years of addi- tional experience confirmed the observations reported by Weisel and me in 1957, namely, that obstruction of the pupil and iris coloboma by a forward displacement of the vitreous face was an important con- tributing factor in such cases. Rupture of the adherence of the vitreous to the iris by intensive mydriatic therapy sometimes alter- nated with miotics has been the most effective medical therapy. Point pressure on the iris through an anesthetized cornea with a lubricated glass rod may disrupt some of the pupillary adhesions and was found to be a valuable supplement to medical therapy. When non-surgical treatment was unsuccessful, peripheral iridectomy or iridotomy was performed with success in eight neglected cases without resorting to rupture of the vitreous face, sclerotomy, or air injections. Attention to the vitreous obstruction in the early stages after cataract extraction reduced the incidence of later vitreous block glaucoma to only six cases out of more than 3,000 cataract extractions. Postoperative gonioscopy revealed the incidence of shallow chamber due to vitreous obstruction of both the coloboma and pupil to be approximately the same in cataract extractions performed with peri- pheral, as compared to complete, iridectomy provided that an ade- quate opening was made near the base of the iris. The incidence of shallow chamber was 5 per cent when the opening did not extend 230 'CtIKenethl C. Stw(ian to witlini approximately one millimecter of the base(, bltt wvas less than 2 pcr cent when the opening wvas basal. Forward displacement of the vitreous face with herniation throtugh the pupil was common, but vitreous herniation into truly basal iris openings seldom was fouind. It was relatively frequent when the openings extended only imidway to the root of the iris. Clinical and microscopic studies re- vealed an anatomic explanation for these observations. In aphakic eves, the face of the vitreous usually was blocked from contact with the extreme periphery of the iris by the ciliary processes and ciliary body. It frequently was in contact with iris in the pupillary area. For cataract extraction an incision entering the anterior chamber in the region of Schwalbe's line is recommended. The iris and vitreous are more apt to become adherent to incisions entering the anterior chamber farther forward in the cornea and it is more difficult to (,btain a basal coloboma. For a complete iridectomy, it is recom- mended that the iris be grasped behind the sphincter so that the peripheral part can be stretched into the wound and excised. For peripheral iridectomy, delivery of the peripheral iris into the incision wvitlh forceps is recommended as preferable to snipping a hole in the iris with scissors introduced into the anterior chamber. Such openings wvere found to be small and seldom basal. Attention to these and other factors, in our cases, has significantly reduced, although not eliminated, late shallowing of the anterior chamber without demonstrable wound leak. REFERENCES 1. Christensen, Leonard, Epithelization of the anterior chamlber, Tr. Am. Ophth. Soc., 58:284-96, 1960. 2. Weisel, John, and K. C. Swan, Mydriatic treatment of shallow chamber after cataract extraction, Arch. Ophth., 58:126-9, Jtuly, 1957. 3. Chandler, P. A., and A. E. \Iaumenee, A mnajor cause of hypotony, Tr. Am. Acad. Ophth., 65:563-74, Jtuly-Aug., 1961. 4. Chandler, Paul, Glaucoma from pupillarv block in aplhakia, Tr. Am. Ophth. Soc., 59:96-102, 1961. D. Swan, K. C., Basal iridectomny for prevention and treatment of persistent shallow chamber after cataract extractioin, Eye Digest, WVatson Gailey Fotundation, Jan., 1958. 6. Swan, K. C., and R. C. Cowger, Mlydriatic treatment of slhallow chamber after cataract extraction, Correspondence, Arcl. Ophth., 59:151-2, Jan., 1958. 7. Shaffer, R. N., The role of vitreous detachment in aphakia aind malignant glaucoma, Tr. Am. Acad. Ophth., 58:217, 1954. 8. Irvine, S. R., Vitreous Changes Before and After Cataract Extraction. In Diseases and Suirgery of the Lens. St. Lotiis, C. V. Mosby, Co., 1957, pp. 166-85. 9. Swani, K. C., Surgical Anatomiiy, in Symposiumiii oIn Glatuicomai-It. St. Loutis, C. V. Mlosby, Co., 1959, pp. 46-9. Shallow Chamber Following Cataract Extraction 231 DISCUSSION DR. S. RODMAN IRVINE. The problem of delayed flat chambers, hypotony, and detached choroid, is to the ophthalmologist what slicing, hooking, and dubbing is to the golfer-a topic for ready discussion but one which is never resolved. Practically everyone in this audience has written on the subject or discussed it at one time or another. Dr. Swan has made three new observa- tions. (1) The "vitreous" block, as he calls it, may be corrected by mechani- cal rupture of the adhesions of the iris to the vitreous face by application of pressure to the iris through the cornea with the tip of a glass rod. And (2) the demonstration that a posterior chamber is usually present in aphakia and (3) that the adhesions form first around the pupillary margin. I think that most experienced surgeons agree with Dr. Swan that peri- pheral iridectomy, as he describes it, is advisable and is one factor in reducing incidence of the syndrome. Of course, as he cautions, one must not cut too peripherally and tear the iris so as to damage the major arterial circle of the iris. Dr. Swan stresses the importance of good wound closure in his newer technique of half lap type incision, but, even with this, his incidence of delayed flat chamber was 7 per cent until he paid more attention to the iridectomy, reducing it to 2 per cent by making the iridec- tomy more peripheral. Dr. Swan prefers peripheral iridectomy to posterior sclerotomy in the initial treatment of cases even though the eye is soft and no evidence of glaucoma has been established. Last year we heard Dr. Chandler discuss a later result of this syndrome, namely, normal or increased pressure, for which he advocated peripheral iridectomy. For the record, I would like to review the mechanism involved, as it appears to me. Aqueous has to go around or through the vitreous to get into the anterior chamber. I believe that, normally, aqueous can permeate the normal vitreous hyaloid [slide] but, certainly, if there is slight wound leak, or inflammation of any kind, the hyaloid can become altered and become adherent to the iris. The vitreous then comes forward, either because of detachment of the vitreous posteriorly, or because of pooling of the aqueous behind the vitreous, pushing it forward, or because of flattening of the chamber due to wound leak-or perhaps all of these. As a result of the vitreous coming forward, it coincidently contracts and pulls on the vitreous base, tending to open the supraciliary and supra- choroidal space, allowing transudation to occur here. This further increases the pressure in the posterior vitreous space relative to the anterior chamber, exaggerating the shallowing of the chamber. If the condition occurs suddenly, and the eye is very soft, one immediately suspects wound leak. As Dunnington and others have shown, these leaks are not always easy to demonstrate. Last year Shaffer suggested demonstra- 232 Kenneth C. Swan tion of leak by injecting weak fluorescein into the anterior chamber and I suggested study of the wound with the corneal microscope after peritomy. If no leak is found and the eye is still hypotensive one would have to assume decrease in aqueous formation due to separated choiroid. If the condition develops slowly, that is, with gradual flattening over a number of days, one might assume that there is a pupillary "vitreous" block with suppression of aqueous secretion, as is emphasized by Maumenee and Chandler. Now, as long as a posterior chamber is present, and Swan has demon- strated this with his pictures, iridectomy will equalize the pressure and tend to deepen the anterior chamber. I have proven this a number of times in shallow chamber following cyclodialysis and hypotony, by deepening the chamber simply by iridectomy. To attempt to prove this theory of relative pupillary block in a soft eye in phthisis bulbi with shallow chamber, I have deepened the chamber by simple iridectomy prior to enucleation. I believe this concept of relative pupillary block should be emphasized in our appraisal of these cases. If the entire back of the iris becomes adherent to a hyalinized vitreous, as sometimes occurs after loss of vitreous, simple iridectomy will not deepen the anterior chamber and one has to make an opening into the vitreous and trephining over the separated choroid, and, in some instances causing a vitreous fistula posteriorly, to reverse the flow of fluid so that the pressure becomes relatively lower in the vitreous and posterior chamber with respect to the anterior chamber. I discussed this in a lecture on the vitreous in 1955, at the Proctor meeting, and Shaffer has also discussed this concept, as have others. So, to summarize the treatment-one tries medical means, moving the pupil with miotics and mydriatics, as originally recommended by Reese, and now, by the new technique of Swan-massaging the iris with a glass rod- closing the wound leak if any is demonstrable-then peripheral iridectomy- then posterior sclerotomy-then section through the vitreous and creation of a vitreous fistula posteriorly, through a posterior sclerotory wound over the detached choroid. I want to present a final slide showing how the incidence of this complication can vary from year to year in the hands of a single surgeon [slide]. In all these cases, I made a keratome incision at the posterior limbus, after peritomy, and enlarged the wound with McGuire scissors. I used three to five post-placed 7-0 corneoscleral sutures on Greishaber needles. We see an incidence of delayed flat chambers comparable to what Dr. Swan reports. Prior to this series, in about 1300 cases, when I was using pure corneal sections with a knife, I so rarely encountered this syndrome that I considered it less important than the 2 per cent incidence of vitreous syndrome. I do believe that faulty wound healing is the primary problem, leading to the cycle of events of forward displacement of vitreous, traction on the supraciliary and suprachoroidal space, choroidal detachment, and Shallow Chamber Following Cataract Extraction 233 increased pressure in the vitreous chamber relative to that in the anterior chamber. For the past year, I have again used knife sections, more forwardly placed in approximately 100 cases and have rarely encountered the syndrome. Dr. Swan's presentation is most important and thoroughly appreciated by all of us experienced enough to have encountered delayed shallowing of the chamber, detached choroid, and hypotony. As he so aptly puts it-many causes may be contributory-and he has emphasized only the role of peripheral iridectomy. DR. WALTER S. ATKINSON. It is always stimulating to hear Dr. Swan's thoughtful presentations. Like other complications in cataract surgery, shallow or flat anterior chambers, particularly at the first dressing, are rare and usually are caused by a leaky wound which responds to repair if the condition persists. For those that occur later, after the tenth day, the cause often is not easily demonstrated. At that time the pupil is usually dilated which may close the peripheral iridotomy or iridectomy openings made at the time of the round pupil extraction. It would seem logical to contract the pupil to open the peripheral hole or holes already present in the iris and allow the aqueous to come forward from the posterior to the anterior chamber as obtained by making a peri- pheral iridectomy as advocated by Dr. Swan. To dilate the pupil more when the chamber is flat one would expect the iris to become adherent to the wound forming anterior synechia. DR. KARL W. ASCHER. One question to the essayist and to the audience: Is the frequency of flat chambers after cataract operation greater when you use hyaluronidase? DR. HAROLD GIFFORD. Just one note on the technique of doing a complete iridectomy. Dr. Swan pointed out that it is important to get the root of the iris. A few years ago I showed a method of grasping the iris in the center between the sphincter and the base. When this is pulled out it pulls the base with the iris, and then you reverse the scissors. The usual iridectomy is done with the curve of the scissors against the eye. Reverse the scissors and cut the other way, the iridectomy comes out with straight pillars. By picking the iris up in the center you get a nice, full iridectomy with a clean bottom. It does away with the root that is left behinld. It leaves vou with beautifuil pillars. It is a most dramatic thliing to see the chambers deepen in your office. Put in a drop of 10 per cent nieosvnephrine and it will deepen while you watch it. The next day the chamber may be flat again. Put in another drop and it will deepen while you watch it. 234 Kenneth C. Swan As soon as the neosynephrine wears off the chamber flattens again. About the fourth day it remains deep and everybody is happy. I would like to ask Dr. Swan if he has any explanation of this effect. DR. HARVrEY E. THORPE. I want to thank Dr. Swan for calling this important subject to our attention. One of the things he has shown in this study is that by means of biomicroscopy and postoperative gonioscopy he was able to better arrive at the basic pathology of complications in these cases with shallow anterior chamber. His gonioscopic illustrations of postoperative findings demon- strated that the iridectomy one does and considers to be basal is frequently proven not to be basal and that the buttonhole iridectomy which one may think to be peripheral turns out not to be truly peripheral unless special pains are taken to make it so. At the risk of repetition, I wish to stress that peripheral iridectomy must be penetrating through all the iris layers and must remain patent to be effectual. Postcataract extraction iridovitreous adhesions may cause complete seclu- sion of the pupil as well as adhesion of the margins of the surgical coloboma. This leads to iris bombe and ultimate angle block. The essayist has demonstrated this sequence of events. He confirmed that the iridovitreal extensive adhesions are responsible for some of the pupil block phenomena which Chandler and others have described. Biomicroscopy can readily be done six or seven days after cataract extraction. Gonioscopy with our four mirror gonioprism can usually be performed without danger five to six weeks after surgery. These methods of examination afford an accurate appraisal of the complicating factors and point to the necessity of restoring communication between the anterior and posterior chamber by early forced mydriasis, by breaking posterior synechia in the manner shown by Dr. Swan and if necessary by surgical intervention. DR. SWAN. I wish to thank Dr. Irvine for his fine discussion, and particularly for bringing out the mechanism. Also I want to pay tribute to his studies of the vitreous after cataract extraction. He has conducted such studies for many years. He mentioned "wound leak." Dr. Cowger and I, some years ago, studied the relationship of unintentional filtration after cataract extrac- tion to shallow chamber. We found no correlation between the incidence of shallow chamber and even large filtrations under the conjunctiva. We concluded that a limbal leak was not a factor as long as the fluid was retained under the flap and did not leak out through the conjunctival incision into the fornix. Dr. Atkinsoni has brought up all importanit poinit. If the incision enters the anterior chamber well forward, it is coniceivable that wide dilatationl of the pupil might block anl iridectomy in the extreme periphery. This is onie reason why I like to have the incision enter in the region of Schwalbe's line. I wish I could answer Dr. Ascher's question about hyaluronidase. I assume Shallow Chamiiber Following Cataract Extractiotn 235 he means by retrobulbar injectioni. There is little doubt that it does enlhanice the spread of the local anesthesia, and that it may prolong anid iintensify hypotony when combined with epinephrine. Dr. Gifford has mentioned the shape of the iridectomy in relationi to the curve of the scissors. It is something that I will investigate. Recurrence of shallow chambers has bothered uIs. We also have had recurrence oIn the day following restoration with mvdriatics. At first I thought it might be related to the known depressant effect of epinephrine on the rate of formation of the aqueous. But in most of these cases, this function already is depressed. We have founld the solution to be more intense mydriasis, continued oIn a 24-hour schedule. I appreciate Dr. Thorpe's discussioni and particularly his emphasis oni the use of the gonioscope. The time of application of the gonioscope is important after cataract extractioni. Too early an applicationi mav cause serious trouble. Eight days, by the way, is the earliest we have applied the glass rod.