• 6 SECTIONGlaucoma Angle Open

After Penetrating Keratoplasty

Key Facts

•Leading cause of blindness following corneal transplant

•Late glaucoma secondary to chronic angle closure with peripheral anterior synechiae formation

•Early elevated pressure secondary to inflammation, retained Healon, hyphema, angle closure, trauma, or angle compression due to over-tightening of sutures or small donor size

•Occurs in up to 31% in early postoperative phase and in 35% with long-term follow-up

•Increased risk in patients with history of glaucoma and aphakia

•Reduced incidence when donor corneal button is 0.5 mm larger than donor bed

Clinical Findings

•Corneal graft edema

•Corneal haze

•Pain

•Redness

•Decreased vision

•Peripheral anterior synechiae

•Excessively tight corneal transplant sutures

•Excessively large cornea donor graft may predispose to peripheral synechiae (Fig. 6.30)

Ancillary Testing

•Pneumotonometry is the most accurate way to measure IOP in patients with significant irregular astigmatism and corneal edema

•Pachymetry

•Visual field and imaging to test for optic nerve damage

•See Primary open angle glaucoma (p. 68)

Differential Diagnosis

•Primary open angle glaucoma

•Steroid response glaucoma

•Inflammatory glaucoma

•Neovascular glaucoma

Treatment

•Topical hypotensive agents

•Trabeculectomy successful in 69–91%

•Trabeculectomy results in corneal transplant graft failure in up to 18%

•Glaucoma drainage devices successful in up to 80% but frequently lead to graft failure

•Trans-scleral cyclophotocoagulation is successful in up to 80% but also leads to frequent graft failure

Prognosis

• Survival of graft is major factor in limiting visual function

• 6 SECTIONGlaucoma Angle Open

Hypotony Maculopathy

Key Facts

•Hypotony defined as IOP ≤5 mmHg but will vary based on central corneal thickness

•Maculopathy manifests with decreased and distorted visual acuity

•Increased incidence after trabeculectomy with antifibrotics (mitomycin-C and 5-fluorouracil)

•Increased risk in young male myopes

•Hypotony occurs in up to 30% of patients after use of antifibrotics during trabeculectomy

•Maculopathy occurs in approximately 10% of patients with hypotony

Mechanism

•Wound or bleb leak

•Over-filtration through sclerostomy site

•Cyclodialysis cleft

•Aqueous hyposecretion (possibly from mitomycin-C exposure)

Clinical Findings

•Decreased vision • Shallow anterior chamber • Iris and/or lens cornea touch • Anterior chamber cell reaction • Anterior and/or posterior synechiae formation • Corneal edema • Cataract formation • Choroidal folds (Fig. 6.31) • Macular edema • Optic nerve head swelling • Choroidal effusions

Ancillary Testing

•Dilated fundus examination

•B-scan ultrasonography may show choroidal effusions

•Optical coherence tomography to evaluate macula

•Ultrasound biomicroscopy may show cyclodialysis cleft

•Fluorescein angiography shows choroidal folds (Fig. 6.32)

Differential Diagnosis

•Bleb over-filtration • Aqueous hyposecretion • Wound leak • Retinal detachment • Choroidal detachment • Uveitis • Phthisis

Treatment

•Identify and manage underlying cause

•Post-trabeculectomy: most often will require surgical revision

•Wound or bleb leak: bandage contact lens, antibiotics, possibly aqueous suppressants, may require surgical correction

•Over-filtering bleb: autologous blood injection, laser to conjunctiva

•Cyclodialysis: close cleft

Prognosis

•Chance of full visual recovery decreases with increased duration of hypotony maculopathy