Tight Scleral Flap Trabeculectomy With Postoperative Laser Suture Lysis

Tight Scleral Flap Trabeculectomy With Postoperative Laser Suture Lysis Shlomo Melamed, M.D., Isaac Ashkenazi, M.D., Joseph Glovinski, M.D., and Michael Blumenthal, M.D.

Thirty eyes of 30 patients underwent tight scleral ftap trabeculectomy. Of these eyes, 22 underwent laser lysis of the scleral ftap sutures, whereas eight eyes did not require such treatment because of low intraocular pressure and active filtering blebs. In the 22 eyes treated, preoperative intraocular pressure was 32.6 :t: 8.3 mm Hg, whereas postoperative and prelaser intraocular pressure was 29.3 :t: 7.4 mm Hg. Immediately after laser suture lysis, intraocular pressure dropped by 22.7 :t: 9.4 mm Hg (P < .01) to 6.6 :t: 7.0 mm Hg, with elevation of the conjunctival bleb in all eyes treated. After a mean follow-up of 14.4 months, intraocular pressure was controlled (s 18 mm Hg) in 20 of the 22 eyes treated (91%). The only major complication was a single case of anterior chamber ftattening with intraocular lens touching the corneal endothelium. Combination of tight scleral flap trabeculectomy with subsequent postoperative laser suture lysis is a safe and effective method for low-level intraocular pressure control. This technique seems to combine the advantages of fullthickness filtration and trabeculectomy by achieving relatively low intraocular pressures while minimizing complications caused by excessive aqueous runoff. FILTERING SURGERY for uncontrolled glaucoma involves the formation of a fistula connecting the anterior chamber and the subconjunctival space, with subsequent effective reduction of intraocular pressure. Two different surgical approaches are currently in use: full-thickness filtration, in which a full-thickness sclerostomy

Accepted for publication Nov. 17, 1989. From the Goldschleger Eye Institute Chaim Sheba Medical Center, Tel-Hashomer, Israel. Reprint requests to Shlomo Melamed, M.D., Goldschleger Eye Institute, Chaim Sheba Medical Center, Tel-Hashomer 52621, Israel.

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is made, connecting the anterior chamber directly to the subconjunctival space; and trabeculectomy, in which the sclerostomy is performed under a scleral flap, which is later sutured back to its original scleral bed in an attempt to minimize aqueous outflow runoff. The main advantage of the first technique is the lower intraocular pressure achieved postoperatively.v? Full-thickness filtration, however, is associated with more postoperative complications related to excessive overflow of aqueous, such as anterior chamber flattening, prolonged hypotony, peripheral anterior synechiae, and cataract formation.tv'" The advantage of trabeculectomy under the scleral flap is the tamponade effect provided by the dissected and resutured sclera over the sclerostomy, with subsequent reduction of aqueous flow-through. Although this procedure provides short-term postoperative stability, however, final intraocular pressure levels are usually higher than intraocular pressure levels after full-thickness filtration, and long-term success of intraocular pressure control is lower." In an attempt to benefit from the advantages of both techniques and minimize complications, trabeculectomy with tight closure of the scleral flap was performed in 22 eyes with uncontrolled glaucoma. Postoperatively, the scleral sutures were cut through the conjunctiva using the argon laser. This method, previously described by Savage and associates.r" provides protection from short-term excessive aqueous runoff followed by planned, controlled relaxation of the scleral flap sutures with modification of aqueous flow and reduction of intraocular pressure.

SUbjects and Methods Twenty-two eyes of 22 patients with uncontrolled glaucoma underwent argon laser suture MARCH,

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TABLE

1

CHARACTERISTICS OF THE STUDY POPULATION PATIENTS (N=22) CHARACTERISTICS

Sex Male Female Diagnosis Primary open-angle glaucoma Pseudoexfoliative glaucoma

NO.

("!o)

12

(54.5)

10

(45.5)

10

(45.5)

4

(18.2)

Angle-closure glaucoma Posttraumatic glaucoma

3

(13.6)

2

(9.1)

Juvenile glaucoma Low-tension glaucoma

2

(9.1)

1

(4.5)

Visual field status Normal

1

(4.6)

Nasal step

8

(36.4)

Paracentral scotoma

3

(13.6)

Complete Bjerrum scotoma

2

(9.1)

5

(22.7)

3

(13.6)

Bjerrum scotoma broken to the periphery Isolated island of vision Glaucoma medications One Two Three Four Laser trabeculoplasty Previous ocular surgery None Extracapsular cataract extraction and intraocular lens implantation Cyclodialysis Penetrating keratoplasty

1

(4.5)

8

(36.4)

6

(27.3)

7

(31.8)

15

(68.2)

16

(72.7)

3

(13.7)

2

(9.1)

1

(4.5)

lysis after tight scleral flap trabeculectomy. The group included 12 men and ten women, and the mean age of the patients was 61.5 years. Diagnosis of glaucoma subtypes included primary open-angle glaucoma, ten eyes; pseudoexfoliative glaucoma, four eyes; chronic angle-closure glaucoma, three eyes; posttraumatic glaucoma, two eyes; juvenile glaucoma, two eyes; and low-tension glaucoma, one eye (Table 1). An additional eight eyes underwent tight scleral flap trabeculectomy but did not need postoperative laser suture lysis because of good control of intraocular pressure (10.2 ± 2.3 mm Hg) after trabeculectomy. The surgical procedure and postoperative care were performed by two of us (S.M. and

March, 1990

J.G.). The same surgical steps were followed in all eyes: 1. Retrobulbar anesthesia with 2% lidocaine and 0.5% bupivacaine hydrochloride solutions was used followed by the application of intermittent digital pressure. 2. A fornix-based conjunctival flap was dissected superotemporally or superonasally with meticulous hemostasis of episcleral and bleeding conjunctival vessels. 3. In cases where Tenon's capsule was especially thick, tenonectomy was performed using the Wescott scissors. 4. A 3- to 4-mm equilateral triangular scleral flap was dissected, half scleral thickness in depth, using the diamond knife and a Beaver No. 64 blade. 5. A beveled paracentesis was made with the diamond knife either at the 3:00 or 9:00 o'clock position, and patency was confirmed by the intracameral introduction of Balanced Salt Solution with the 30-gauge cannula. 6. A 2 x 2-mm trabeculectomy was performed under the scleral flap using the diamond knife followed by basal peripheral iridectomy with Vanna's scissors. 7. The scleral flap was closed with three 9/0 nylon sutures one at the apex and one at each side of the triangle. The tightness of these sutures was carefully adjusted to maintain the anterior chamber depth and restrict fluid runoff around the flap edges to little or no flow. 8. The conjunctiva was closed with two 7/0 silk sutures anchored at the corneoscleral limbus at each side. The wound was carefully checked for leakage after the intracameral introduction of Balanced Salt Solution and the application of 2% fluorescein solution. 9. A mixture of betamethasone and gentamicin was injected to the sub conjunctiva away from the filtration site. 10. Antibiotic ointment was applied to the cornea, and the eye was patched. Postoperative treatment included cycloplegic drops twice daily and corticosteroid drops four times daily starting from the first day after surgery. Visual acuity, intraocular pressure measurement, and slit-lamp examination of the anterior chamber and the appearance of the filtration bleb were performed daily for two weeks after surgery. Criteria indicating that the immediate relaxation of the scleral flap sutures was required included an intraocular pressure 18 mm Hg or higher and a flat filtration bleb with a deep anterior chamber. These criteria were believed to indicate high resistance to

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aqueous flow through the tightly closed scleral flap. Before laser treatment, gonioscopy was performed to confirm patency of the sclerostomy with no iris, ciliary processes, or fibrin clot occluding its entrance. For the laser suture lysis procedure, the following steps were taken in all eyes treated: 1. Proparacaine hydrochloride drops were applied to the treated eye. 2. The Hoskins lens" was placed against the conjunctiva overlying the scleral flap sutures. Gentle pressure with the lens was usually sufficient to blanch the conjunctival vessels, allowing a direct view of the scleral sutures (Figure). In cases where Tenon's capsule was thick or the conjunctiva was unusually vascular, and the sutures were obscured, more pressure with the lens usually resulted in better visibility and safe treatment. 3. Argon laser parameters are spot size of 50 11m, exposure time of 0.1 second, and power ranging from 500 to 1000 mW. Special care was taken to focus the laser beam posterior to the conjunctiva to avoid inadvertent burning or perforation. 4. One, two, or three sutures were cut, depending on the immediate response to treatment, extent of bleb elevation, anterior chamber shallowing, and intraocular pressure level. 5. Patients were followed up immediately after laser treatment and daily thereafter until the postoperative course was considered stable. Features examined included visual acuity, in-

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TABLE 2 INTRAOCULAR PRESSURE BEFORE AND AFTER TRABECULECTOMY IN 30 EYES INTRAOCULAR PRESSURE (MM HG)

MEAN

S.D.

RANGE

Preoperative Postoperative

31.4 21.4

7.9 12.7

20-48 2-45

traocular pressure level, filtration bleb appearance, anterior chamber depth by means of ophthalmoscopy, and visual field analysis.

ResUlts

Twenty-two of 30 eyes underwent laser suture cutting through the conjunctiva after a tight scleral flap trabeculectomy. Preoperative intraocular pressure was 31.4 ± 7.9 mm Hg, whereas the intraocular pressure after surgery was 21.4 ± 12.7 mm Hg, a mean drop of 10.0 mm Hg (Table 2). If only the 22 eyes treated are analyzed, however, the mean preoperative intraocular pressure was 32.6 ± 8.3 mm Hg, and intraocular pressure one day after trabeculectomy was 29.3 ± 7.4 mm Hg. In eight of 30 eyes operated on, the mean intraocular pressure dropped to 10.2 ± 4.9 mm Hg, and these eyes did not undergo laser suture lysis. After laser suture lysis in the 22 eyes, intraocular pressure

Figure (Melamed and associates). One of the scleral flap sutures seen through the Hoskins lens before laser treatment.

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TABLE 3 INTRAOCULAR PRESSURE BEFORE AND AFTER LASER SUTURE LYSIS IN 22 EYES INTRAOCULAR PRESSURE (MM HG)

MEAN

Preoperative Before laser After laser Last visit

S.D.

RANGE

32.6

8.3

29.3

7.4

20-48 18-45

6.6 14.2

7.0

1-27

5.8

8-34

dropped to 6.6 ± 7.0 mm Hg within one hour after treatment, which is a mean drop of 22.7 ± 9.4 mm Hg (P < .01) (Table 3). At the last visit, the mean intraocular pressure was 14.2 ± 5.8 mm Hg after a mean follow-up of 14.4 months (range, four to 24 months). Relevant clinical data after trabeculectomy and laser suture lysis are summarized in Tables 4 to 7. One day after trabeculectomy, intraocular pressure was greater than or equal to 18 mm Hg in 13 eyes and under 18 mm Hg in 17 eyes. Only two eyes displayed substantial anterior chamber shallowing, both because of conjunctival wound leak. Filtration bleb was flattened in 15 eyes and elevated in 15 eyes (Table 4). Analysis of the 22 eyes before laser suture lysis (Table 5) disclosed that all eyes had an intraocular pressure of greater than or equal to 18 mm Hg with deep anterior chamber and flat bleb. Eleven eyes underwent laser treatment one day after surgery (50%), five eyes underwent the procedure two days after surgery (22.7%), and six TABLE 5 CLINICAL FINDINGS ONE HOUR BEFORE LASER SUTURE LYSIS EYES (N = 22) CHARACTERISTICS

NO.

(%j

Days postoperatively 1 2

11

(50.0) (22.7) (27.3)

~3

Intraocular pressure ,,;:18 mm Hg >18 mm Hg Depth of anterior chamber ,,;:2 corneal thicknesses >2 corneal thicknesses Bleb appearance Elevated Flattened

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5 6 0 22

(0.0) (100)

0 22

(0.0) (100)

0 22

(0.0) (100)

TABLE 4 CLINICAL RESPONSE ONE DAY AFTER TRABECULECTOMY EYES (N = 30) CLINICAL FINDINGS

Intraocular pressure ,,;:18 mm Hg >18 mm Hg

NO.

(%)

13

(43.3)

17

(56.7)

Anterior chamber depth ,,;:2 corneal thicknesses

2

(6.7)

>2 corneal thicknesses

28

(93.3)

15 15

(50.0) (50.0)

Bleb appearance Elevated Flattened

eyes underwent the procedure three days or more after trabeculectomy (27.3%). One hour after laser suture lysis, intraocular pressure was less than or equal to 18 mm Hg in 20 of 22 eyes treated (90.9 %). Filtration bleb was elevated in all eyes treated, and four eyes (18.2%) had substantial shallowing of the anterior chamber to less than two corneal thicknesses axially (Table 6). At the end of the follow-up period, the intraocular pressure was controlled (:5 18 mm Hg) in 20 eyes (90.9%). Anterior chamber was deep in all eyes, and the bleb was elevated in all eyes, but only 16 eyes had conjunctival microcystic changes. In the two eyes that failed, no such changes could be demonstrated (Table 7). Visual field analysis showed no change attributed to glaucoma from pretrabeculectomy values. The average interval between trabecuIectomy

TABLE 6 CLINICAL FINDINGS ONE HOUR AFTER LASER SUTURE LYSIS EYES (N=22)

Intraocular pressure ,,;:18 mm Hg >18 mm Hg Depth of anterior chamber ,,;:2 corneal thicknesses >2 corneal thicknesses Bleb appearance Elevated Flattened

NO.

(%)

20 2

(90.9) (9.1)

4 18

(18.2) (81.8)

22 0

(100) (0.0)

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TABLE 7 LONG-TERM RESULTS EYES (N;22) CHARACTERISTICS

Intraocular pressure :s18 mm Hg >18 mm Hg

NO.

(%)

20 2

(90.9) (9.1)

0 22

(0.0) (100)

22

(100)

0

(0.0)

Depth of anterior chamber :s2 corneal thicknesses >2 corneal thicknesses Bleb appearance Elevated Flattened

and laser suture lysis was 2.5 ± 2.7 days (range, one to 13 days). Cutting of the sutures with the argon laser was successful in 21 of 22 eyes. In one eye, we were unable to lyse the sutures even with a laser power of 1,500 mW, probably because of episcleral bleeding absorbing the argon laser energy. In this patient, Nd:YAG laser was used successfuIly with seven pulses of 1.2 m] each. to open the sutures without complication. . In five eyes (22.7%), lysis of one suture only was sufficient for intraocular pressure control and active bleb formation. Nine (40.9%) and eight (36.4%) eyes had two and three sutures cut respectively for achieving the same goal. The average laser power required for lysis of one suture was 700 mW (range, 500 to 1,000 mW), with applications totaling two per suture. In 20 eyes, laser treatment was associated with a sharp drop of in traocular pressure within the first hour after treatment. AIl of these eyes had an elevated filtration bleb, and four (18.2%) responded with shaIlowing of the anterior chamber, which usuaIly resolved within one to three days. There was no conjunctival perforation or leak after laser treatment. There was one case of mild subconjunctival bleeding, which resolved spontaneously after two days. One pseudophakic eye responded with excessive shalIowing of the anterior chamber with forward dislocation of the intraocular lens and lens-corneal contact. This condition resolved after three days of conservative medical treatment, and no surgical deepening of the anterior chamber was required. After a mean foIlow-up of 14.5 months, intraocular pressure was controlled in 20 eyes. Of

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these eyes, only four required antiglaucoma therapy (20%). AlI eyes that failed had flat or vascular filtration blebs, whereas among successful eyes, high blebs with microcystic changes were noted in 16 of 20 eyes (80%). Visual acuity improved in two eyes, worsened in five eyes, and remained unchanged in 15 eyes. Documented progression of cataract was detected in the five eyes with worsened vision.

Discussion

The partial-thickness glaucoma filtering procedure, commonly known as trabeculectorny, is currently the most widely used surgical treatment for glaucoma. The procedure, first described by Cairns in 1968,12 is associated with fewer complications than full-thickness operations, which include complications such as prolonged hypotony, flattening of the anterior chamber, corneal decompensation, peripheral anterior synechiae, and cataract formation.1.2.4.7.13.16 The main advantage of the full-thickness filtering procedure, however, is the lower intraocular pressure achieved postoperatively.!" This low intraocular pressure is especiaIly crucial for eyes with advanced glaucoma where the optic nerves are already severely damaged and only intraocular pressure of less than or equal to 15 mm Hg is considered sufficient for preventing further damage. Because achieving these intraocular pressure levels is usuaIly associated with excessive overfiltration of aqueous and shortterm complications related to aqueous overflow, this technique has been abandoned by many glaucoma surgeons. Our study, as well as others,":" suggests that combining the tight scleral flap trabeculectomy and early suture lysis with the laser is advantageous. The 91 % success rate with an anterior chamber shaIlowing rate of only 18% indicates that this method is efficient and relatively safe. Our results suggest that despite the surgeon's effort to tightly seal the flap with three sutures, the intraocular pressure dropped postoperatively to the low teens (~ 15 mm Hg) without laser suture lysis in eight eyes. We did not predict which eye would have intraocular pressure reduction. The release of the apical suture seems to have had the most dramatic effect on both reduction of intraocular pressure and bleb formation. Because we believed during surgery that the

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apical suture was the most effective suture in closing the flap, it was chosen to be the first suture to be lysed. In 16 eyes, however, this was not sufficient to effectively lower the intraocular pressure or form a functioning bleb, and two sutures (nine eyes) or three sutures (eight eyes) had to be released. Unlike Savage and associares." we could not demonstrate more hypotony and shallowing of the anterior chamber after the release of the key suture (in our case, the apical suture). We agree, however, that some sutures may contribute more to aqueous flow resistance, depending on the tightness of the suture and the position of scleral flap edges. One day postoperatively, eight eyes treated with laser developed shallowing of the anterior chamber. Only one eye, however, had lenscorneal contact jeopardizing the corneal endothelium. Eyes treated with laser two days after surgery did not display anterior chamber shallowing, and this lag time may be considered safe. Apparently, proper sealing of the conjunctival flap is already significant two days after surgery. This sealing with the subsequent increase in resistance to aqueous flow is preferred before laser suture lysis, because it minimizes the rate of anterior chamber flattening and risks such as corneal damage, cataract formation, and prolonged hypotony. To address whether trabeculectomy and laser suture lysis is superior to trabeculectomy or full-thickness filter alone, one must compare success and complications rates. The success of the procedure must be compared with the fullthickness operations, because the goal is to attain low intraocular pressures. If the definition of success is an intraocular pressure of 16 mm Hg or less, the success rate drops only to 81.8% (18 patients), which is still high. If success is defined as an intraocular pressure of 18 mm Hg or less, our success was 91 % (20 patients), which is comparable to the success rate of 94% reported two years after full-thickness filtration." The rate of complications was surprisingly low in our series. Interestingly, there was no conjunctival burning, perforation, or leak after laser suture lysis. Early cutting of sutures was associated with anterior chamber shallowing in four of 11 eyes treated one day posttrabeculectomy with laser suture lysis (36.4%), and flattening with lens-corneal contact in one eye only. Long-term decrease of visual acuity related to cataract progression has been detected in five eyes (22%), which is similar to the rate of cataract progression of 16% after a similar Pro-

cedure," or 21 % described after trabeculectorny," but substantially less than the rate reported after full-thickness filtration (34% to 38%). The results of our study strongly suggest that tight scleral flap trabeculectomy with subsequent laser suture lysis is a safe and efficient method for controlling intraocular pressure at relatively low levels while minimizing complications associated with aqueous overflow. Sequential release of sutures starting at least two days after surgery will further reduce the rate of anterior chamber flattening and other related complications.

References 1. Watson, P.: Trabeculectomy. Trans. Ophthalmol. Soc. U.K. 89:523, 1969. 2. Drance, S. M., and Vargas, E.: Trabeculectomy and thermosclerectomy. A comparison of two procedures. Can. J. Ophthalmol. 8:413, 1973. 3. Spaeth, G. L., Joseph, N. H., and Fernandes, E.: Trabeculectomy. A reevaluation after three years and a comparison with Scheies procedure. Trans. Am. Acad. Ophthalmol. Otolaryngol. 79:349, 1975. 4. Blondeau, P., and Phelps, C. D.: Trabeculectomy vs thermosclerostomy. A randomized prospective clinical trial. Arch. Ophthalmol. 99:810, 1981. 5. Simmons, R. J., and Singh, O. S.: Shell tamponade technique in glaucoma surgery. In Cairns, J. E., Drance, S. M., and Hoskins, H. D., Jr. (eds.): Symposium on Glaucoma. Transactions of the New Orleans Academy of Ophthalmology. St. Louis, C. V. Mosby, 1981, pp. 266-279. 6. Lamping, K. A., Bellows, A. R., Hutchinson, B. T., and Afran, S. 1.: Long-term evaluation of initial filtration surgery. Ophthalmology 93:91, 1986. 7. Watkins, F. H., Jr., and Brubaker, R. F.: Comparison of partial-thickness and full-thickness filtration procedures in open-angle glaucoma. Am. ]. Ophthalmol. 86:756, 1978. 8. Savage, J. A., and Simmons, R. j.: Staged glaucoma filtration surgery with planned early conversion from scleral flap to full-thickness operation using argon laser. Ophthalmic Laser Ther. 1:201, 1986. 9. Simmons, R. J., Savage, J. A., Belcher, C. D., and Thomas, J. V.: Usual and unusual uses of the laser in glaucoma. In Beckman, H., Campbell, D. G., and L'Esperance, F. A., Jr. (eds.): Symposium on the Laser in Ophthalmology and Glaucoma Update. Transactions of the New Orleans Academy of Ophthalmology. St. Louis, C. V. Mosby, 1985, pp. 154176. 10. Savage, J. A., Condon, G. P., Lytle, R. A., and Simmons, R. J.: Laser suture lysis after trabeculectomy. Ophthalmology 95:1631,1988.

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11. Hoskins, H. D., and Migliazzo, c., Jr.: Management of failing filtering blebs with the argon laser. Ophthalmic Surg. 15:731, 1984. 12. Cairns, J. E.: Trabeculectomy. Preliminary report of a new method. Am. J. Ophthalmol. 66:673, 1968. 13. Drance, S. M., and Bargass, E.: Trabeculectomy and thermosclerostomy. A comparison of two procedures. Can. J. Ophthalmol. 8:413, 1973.

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14. Schwartz, P. L., Ackerman, J., Beards, J., Wessely, Z., Goodstein, S., and Ballen, P. H.: Further experience with trabeculectomy. Ann. Ophthalmol. 8:207, 1976. 15. Kietzman, B.: Glaucoma surgery in Nigerian eyes. A five-year study. Ophthalmic Surg. 7:52, 1976. 16. Shields, M. B.: Trabeculectomy vs full-thickness filtering operation for control of glaucoma. Ophthalmic Surg. 11:495, 1980.

OPHTHALMIC MINIATURE

The Chinese peasant, like the Egyptian, believed in the glow of the eat's eyes at night to ward off evil spirits, but the Chinese carried the Egyptian's fascination with the eyes a step farther. They believed it was possible to tell time this way-that from dawn the pupil in the eat's eye gradually contracted until it became, at noon, a perpendicular hairline. And then, during the afternoon, the hairline's dilation gradually increased until it was bedtime for people and guard time for cats. Cleveland Amory, The Cat Who Came for Christmas New York, Penguin Books, 1987, p. 86