Post-Surgical Management of Glaucoma and Complications of Glaucoma Surgery

Overview

Differential Diagnosis Framework

A. INCREASED POSTOPERATIVE IOP AFTER FILTERING PROCEDURE

Grading of Anterior Chamber Shallowing

• Grade 1: Peripheral iris-cornea contact
• Grade 2: Entire iris in contact with cornea
• Grade 3: Lens (or lens implant or vitreous face) to corneal contact

Treatment (Step-by-Step)

1. Gonioscopy first - essential before starting any treatment to determine the cause.
2. Bleb not formed, deep anterior chamber: Apply light ocular pressure (Carlo Traverso Maneuver) to see if the sclerostomy will drain. In fornix-based procedures, take care not to disrupt the limbal wound.

   If the sclerostomy is blocked with iris, any globe pressure is contraindicated due to risk of further iris incarceration.

3. Laser suture lysis or removal of releasable sutures - may be indicated to increase filtration around the scleral flap.
4. Sclerostomy obstruction management:
   • Iris: Topical pilocarpine or slow intracameral acetylcholine (within 2-3 days). If failed: transcorneal mechanical iris retraction, argon laser iridoplasty.
   • Vitreous: YAG laser photodisruption of the sclerostomy.
   • Blood or fibrin: Time, or intracameral tissue plasminogen activator (tPA, 10 µg).
5. Tube (glaucoma drainage device) obstruction: Remove stent suture or lyse ligature suture. Use caution - IOP may drop dramatically if tube opened before postoperative month 1.
6. Suprachoroidal effusion/hemorrhage:
   • Mild IOP rise + formed chamber: observation + medical management.
   • Persistent chamber flattening, corneal-lenticular touch, chronic retinal fold apposition, intolerable pain: surgical drainage.
   • Delay drainage at least 10 days in cases of suprachoroidal hemorrhage.
7. If above measures fail: reoperation.

B. LOW POSTOPERATIVE IOP AFTER FILTERING PROCEDURE (Hypotony)

• IOP <7-8 mmHg: Risk of flat anterior chamber, choroidal detachment, suprachoroidal hemorrhage.
• IOP <4 mmHg: Risk of macular hypotony maculopathy and corneal edema.

Differential Diagnosis and Treatment by Bleb/Chamber Status

• A large bleb in the first few weeks is often desirable after trabeculectomy.
• Treat if: still present 6-8 weeks post-op, symptomatic, IOP decreasing, or anterior chamber shallowing.
• Treatment: topical atropine 1% b.i.d., intracameral viscoelastic, possibly autologous blood injection into the bleb.
• Observe if IOP is low but stable, vision stable, and anterior chamber deep.

• Cycloplegics (atropine 1% t.i.d.) and careful observation.
• If chamber becomes more shallow, IOP decreases as bleb flattens, or choroidal detachment develops: reform anterior chamber with viscoelastic.

• Perform Seidel test to check for wound leak.
  • If positive: aqueous suppressants, antibiotic ointment, bandage contact lens, patching, or surgical closure.
  • If negative: look for cyclodialysis cleft (gonioscopy + UBM) or serous choroidal detachments.
    • Cyclodialysis cleft: cycloplegics, laser/cryotherapy to close, or surgical closure.
    • Serous choroidal detachment: usually observed, resolves as IOP normalizes.

• Prompt correction required.
• Office-based: reformation with viscoelastic.
• Surgical: drainage of choroidal detachment, reformation of anterior chamber ± revision of scleral flap/tube, or cataract extraction ± other procedures.

C. BLEB INFECTION (BLEBITIS) - Section 9.19

Definition

Grading

Signs

• Grade 1: Milky bleb with loss of translucency, microhypopyon in bleb loculations, frank purulent material, intense conjunctival injection. IOP usually unaffected.
• Grade 2: Grade 1 + AC cell/flare ± anterior chamber hypopyon; no vitreous inflammation.
• Grade 3: Grade 2 + vitreous involvement (same appearance as endophthalmitis but with bleb involvement).

Symptoms

Workup

1. Slit lamp exam of bleb, anterior chamber, vitreous. Seidel test for bleb leak. Gonioscopy for microhypopyon.
2. Culture bleb or anterior chamber tap for Grade 2. If Grade 3: treat as endophthalmitis.
3. B-scan ultrasound to identify vitritis if visualization is difficult.

Common Organisms

• Early post-op: S. epidermidis, S. aureus, other Gram-positive organisms.
• Late (months-years): Streptococcus, Haemophilus influenzae, S. aureus, Moraxella, Pseudomonas, Serratia.

Treatment

• Option A: Fortified cefazolin or vancomycin + fortified tobramycin or gentamicin, alternating every 30 minutes (first 24 hours). Loading dose: 1 drop each every 5 minutes x 4 doses.
• Option B: Fluoroquinolones q1h around the clock after a loading dose.
• Reevaluate at 6-12 hours and 12-24 hours. Must not be getting worse.
• May treat concurrent bleb leak with aqueous suppressants and cycloplegia.

• Same as Grade 1, plus cycloplegics.
• Consider oral fluoroquinolones (e.g., ciprofloxacin 500 mg p.o. b.i.d. or moxifloxacin 400 mg daily).
• More careful, frequent monitoring.

• Treat as endophthalmitis. Preference for early pars plana vitrectomy - bleb-associated endophthalmitis is more fulminant than post-cataract endophthalmitis.

D. COMPLICATIONS OF ANTIMETABOLITES (5-Fluorouracil, Mitomycin C)

• Corneal epithelial defects
• Corneal edema
• Conjunctival wound leaks
• Bleb overfiltration
• Bleb rupture
• Scleral thinning and perforation
• Increased risk of blebitis (long-term)

E. COMPLICATIONS OF CYCLODESTRUCTIVE PROCEDURES

• Pain, uveitis, decreased vision
• Cataract
• Hypotony
• Scleral thinning
• Choroidal effusion
• Suprachoroidal hemorrhage
• Sympathetic ophthalmia
• Phthisis bulbi (end-stage globe atrophy)

F. MISCELLANEOUS COMPLICATIONS OF FILTERING PROCEDURES

• Cataracts
• Corneal edema, corneal delle (drying/thinning adjacent to bleb)
• Endophthalmitis
• Uveitis
• Hyphema
• Bleb dysesthesia (discomfort/foreign body sensation)

G. COMPLICATIONS OF TUBE-SHUNT (DRAINAGE DEVICE) IMPLANTS

• Cataracts
• Corneal edema
• Endophthalmitis
• Hyphema
• Scleral perforation
• Diplopia
• Tube/implant erosion through conjunctiva

Key Post-Operative Monitoring Points