Eligibility Criteria and Determination of Follow-up Period

This retrospective case series was conducted in accordance with the tenets set forth in the Declaration of Helsinki and was approved by the Institutional Review Board at UCLA before the study began. Eyes that underwent trabeculectomy with intraoperative use of either MMC or 5-FU during the time interval between December 1993 and March 2013 and that were followed up for ≥1 year at the Jules Stein Eye Institute were included in the study. Eyes that underwent subsequent implantation of a glaucoma drainage device within the first postoperative year and those with a history of previous endophthalmitis or blebitis were excluded.

The follow-up period was determined as the interval between trabeculectomy and the last office visit. Intraocular surgeries such as the insertion of a glaucoma drainage device, scleral buckling, vitrectomy, combined surgery, or development of malignant glaucoma or phthisis marked the end of follow-up (ie, that eye was censored). The occurrence of a bleb-related infection was the event of interest (ie, failure), and the follow-up period was determined to be less than 1 year for those eyes that developed bleb-related infections during the first postoperative year. If both eyes of the same patient were eligible, both eyes were included in the study.

Surgical Technique

All eyes were operated with peribulbar anesthesia with 2–4 mL of 2% lidocaine. A conjunctival flap was created superiorly in either a fornix-based or limbus-based manner. The location of the bleb was determined from the operative notes. Typically, a superior peritomy was created about 4 clock hours (from 10 o’clock to 2 o’clock) wide for fornix-based flaps. For limbus-based flaps, the conjunctiva just anterior to the superior rectus insertion was elevated and cut, then the incision was extended temporally and nasally for a total of 8–10 mm. The Tenon capsule was then elevated and incised in a similar fashion. Exceptions occurred in 5 eyes where the blebs were made in the superonasal quadrant and in 1 eye where the bleb was made in the superotemporal quadrant. A scleral rectangular flap (approximately 3 × 3 mm) was outlined with light wet-field cautery. The episcleral bed was dried and a large (approximately 6 × 12 mm) Merocel sponge(Beaver-Visitec International Inc, Waltham, MA) soaked in either MMC (0.2–0.4 mg/mL) or 5-FU (50 mg/mL) was applied to the episcleral bed for 0.25–5 minutes.

After removal of the sponge, the exposed episcleral and Tenon areas were copiously irrigated with balanced salt solution. A partial-thickness scleral flap hinged at the superior limbus was made. A trabecular meshwork/corneal block 1 × 2 mm in size was resected under the anterior-most portion of the scleral flap. A basal iridectomy was performed and the scleral flap was sutured with 2–5 interrupted sutures to approximate the scleral flap onto the scleral bed. The conjunctiva was placed back and sutured in a watertight fashion. A paracentesis was made and the bleb was elevated by injecting balanced salt solution into the anterior chamber. The eye was inflated to a physiologic pressure with the anterior chamber completely formed. All surgery was performed by 5 glaucoma specialists at Jules Stein Eye Institute. Topical antibiotic eye drops were prescribed for 1 week after surgery and topical corticosteroids were used for 4–6 weeks postoperatively. Laser suture lysis was performed as needed with a diode laser from 1 to 6 weeks postoperatively. All patients were advised to avoid the use of contact lenses postoperatively.

Bleb revision was performed for the treatment of high thin blebs, bleb dysesthesia, bleb leak, and overfiltering blebs with hypotony maculopathy. The technique of surgical bleb revision followed a method previously reported. Resuturing of the trabeculectomy flap was performed in most of the revisions; in some cases a pericardial graft was required to reinforce the sclera. When indicated, drainage of choroidal effusions and reformation of the anterior chamber was also performed.

Data Collection and Definition of Parameters

Data were collected by retrospective review of medical records. Table 1 describes the clinical and demographic characteristics of the patients. Those with a history of any organ transplantation, chronic administration of oral corticosteroid or immunosuppressant, who were on chemotherapy, who were diagnosed as having seropositive human immunodeficiency virus (HIV), end-stage renal disease, or diabetes mellitus were considered to be immunocompromised.

Table 1

Results From Survival Analysis of Eyes That Underwent Trabeculectomy

Parameter	Total Number of Eyes	Number of Bleb-Related Infections (%)	Log-Rank Test	Generalized Estimating Equation
Demographic characteristics
Sex a
Male	857	7 (0.8)	.159	.151
Female	1102	17 (1.5)
Age a
≥50 years	1761	18 (1.0)	.044	.074
<50 years	198	6 (3.0)
Race			.298	.210
White	1160	17 (1.5)
Asian	276	5 (1.8)
Black	185	1 (0.5)
Hispanic & others	338	1 (0.3)
Systemic conditions
Diabetes mellitus
No	1766	21 (1.2)	.524	.546
Yes	193	3 (1.6)
Hypertension
No	1396	18 (1.3)	.895	.895
Yes	563	6 (1.1)
Immunocompromised state (diabetes included)
No	1756	21 (1.2)	.634	.646
Yes	203	3 (1.5)
Types of glaucoma a			.000	.000
POAG	1411	15 (1.1)
PACG	141	1 (0.7)
Pigmentary glaucoma	39	4 (10.3)
Juvenile glaucoma	18	2 (11.1)
All other secondary	350	2 (0.6)
Lens status
Phakic	1309	19 (1.5)	.311	.293
Pseudophakic, aphakic	650	5 (0.8)
Laterality
OD	977	11 (1.1)	.657	.656
OS	982	13 (1.3)
Surgical factors
Antimetabolites a
MMC	1926	22 (1.1)	.019	.084
5-FU	33	2 (6.1)
Application duration of MMC (min)
MMC <3	1804	19 (1.0)	.365	.397
MMC ≥3	122	3 (0.2)
Type of conjunctival flap
Fornix	968	11 (1.1)	.597	.601
Limbus	991	13 (1.3)
Two or more filtration surgeries
No	1663	21 (1.3)	.422	.398
Yes	296	3 (1.0)
Previous trabeculectomy
No	1857	24 (1.3)	NA	NA
Yes	102	0 (0.0)
Postoperative interventions
Laser suture lysis
No	1183	18 (1.5)	.371	.359
Yes	776	6 (0.8)
Needling and/or 5-FU injection
No	1843	23 (1.2)	.717	.703
Yes	116	1 (0.9)
Bleb revision
No	1791	22 (1.2)	.759	.752
Yes	168	2 (1.2)
Surgical complications
Early leak a
No	1797	18 (1.0)	.003	.013
Yes	162	6 (3.7)
Shallow or flat anterior chamber
No	1861	24 (1.3)	NA	NA
Yes	98	0 (0.0)
Hypotony maculopathy
No	1899	23 (1.2)	.905	.906
Yes	60	1 (1.7)
Choroidal effusion a
No	1693	17 (1.0)	.056	.082
Yes	266	7 (2.6)
Hyphema a
No	1751	17 (1.0)	.018	.037
Yes	208	7 (3.4)
Hypotony a
No	1581	15 (0.9)	.127	.145
Yes	378	9 (2.4)
Prolonged hypotony
No	1880	22 (1.2)	.516	.384
Yes	79	2 (2.5)
Late leak (positive Seidel) a
No	1854	8 (0.4)	.000	.000
Yes	105	16 (15.2)
Cataract surgery during follow-up
No	1215	12 (1.0)	.707	.707
Yes	744	12 (1.6)
Bleb morphology
Avascular bleb
No	1177	2 (0.2)	.000	.000
Yes	782	22 (2.8)
High bleb
No	1909	20 (1.0)	.001	.012
Yes	50	4 (8.0)
Thin-walled bleb
No	1441	5 (0.3)	.000	.000
Yes	518	19 (3.7)
Low bleb
No	1282	22 (1.7)	.006	.002
Yes	678	2 (0.3)
Fully functioning bleb a
No	841	2 (0.2)	.000	.000
Yes	1118	22 (2.0)
Blepharitis
Total blepharitis
No	1741	18 (1.0)	.082	.115
Yes	218	6 (2.8)
Chronic blepharitis a
No	1917	21 (1.1)	.001	.016
Yes	42	3 (7.1)
Episodic blepharitis
No	1783	21 (1.2)	.798	.801
Yes	176	3 (1.7)
Chronic use of oral steroid
No	1929	24 (1.2)	NA	NA
Yes	30	0 (0.0)
Use of punctal plugs a
No	1921	22 (1.1)	.011	.068
Yes	38	2 (5.3)
Groups a			.000	.000
Group 1 b	1661	10 (0.6)
Group 2 c	167	1 (0.6)
Group 3 d	131	13 (9.9)

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