What are the indications for using tissue adhesive (cyanoacrylate) without a Tenon's patch graft in cases of keratitis with corneal perforation?

Tissue Adhesive (Cyanoacrylate) Without Tenon's Patch in Keratitis

Tissue adhesive alone (without Tenon's patch graft) is indicated for small corneal perforations or areas of marked thinning/early descemetoceles in keratitis when the defect is ≤3 mm, located at the bottom of a crater (not ballooning), and has a clean, compact, dry base that allows proper adhesion. 1

Primary Indications for Tissue Adhesive Alone

Size and Location Criteria

• Small perforations ≤3 mm in diameter are the ideal candidates for tissue adhesive without additional patch grafting 1, 2
• Peripheral location may allow tissue adhesive to serve as definitive treatment, while central or paracentral locations typically require the adhesive as a temporizing measure before elective repair 1
• The defect must be at the bottom of a crater rather than a ballooning descemetocele for optimal adhesion 1

Wound Characteristics

• The base must be clean, compact, and completely dry for proper adhesion 1, 3
• The area should be de-epithelialized to create optimal conditions for glue adherence 1, 3
• Early descemetoceles with marked thinning but minimal tissue loss are suitable 1

Clinical Context in Keratitis

Progressive Corneal Stromal Thinning

• Tissue adhesive is indicated when there is extremely thin cornea, impending perforation, or frank perforation complicating bacterial keratitis 1
• It serves as one of several treatment options alongside penetrating keratoplasty and lamellar keratoplasty for progressive stromal thinning 1
• Application should occur after addressing the underlying infection with appropriate antimicrobial therapy 1

When to Add Tenon's Patch

• Larger perforations (>3 mm) require Tenon's patch graft with cyanoacrylate glue rather than adhesive alone 1
• The guidelines explicitly state that Tenon's patch with cyanoacrylate is "an effective option for the management of larger perforations" 1
• Research supports that perforations 3.5-4.5 mm benefit from intracorneal scleral patch supported cyanoacrylate application 4

Application Technique

Preparation

• Ensure the wound base is completely dry before application, as moisture prevents proper adhesion 1, 3
• For leaking descemetoceles, inject an air bubble into the anterior chamber to temporarily halt leakage while applying glue 1
• Use sterile product to reduce risk of secondary infection, though tissue adhesive is not FDA-approved for ocular use 1

Application Methods

• Apply using a 30-gauge needle, wooden end of cotton applicator, or micropipette 1, 3
• Use the minimum quantity necessary to seal or support the defect 1, 3
• A thin layer of adhesive can remain in place for 6 weeks or longer if applied to a clean and compact base 1

Post-Application Management

• Apply a bandage contact lens to prevent dislocation of the glue and provide comfort 1, 3
• Continue appropriate antimicrobial therapy for the underlying keratitis 1
• Monitor closely for signs of infection, as bandage contact lens use increases risk of microbial keratitis 5, 6

Critical Contraindications and Pitfalls

Do Not Use Tissue Adhesive Alone When:

• Perforation size >3 mm - these require Tenon's patch or other tissue support 1
• Ballooning descemetocele present - adhesive works poorly on convex surfaces 1
• Significant tissue loss exists - consider tectonic grafting procedures 7
• Base cannot be adequately dried - moisture prevents proper adhesion 1, 3

Important Warnings

• Never use fibrin glue for corneal perforations or descemetoceles, as it biodegrades too rapidly before healing occurs 1
• Approximately 16-27% of cases fail to seal with tissue adhesive alone and may require repeat application or progression to keratoplasty 8, 2
• 40-50% of perforations ≤3 mm heal with adhesive application alone, while others require subsequent penetrating keratoplasty 8, 2

Expected Outcomes

Success Rates

• Research shows 83.6% complete sealing for perforations ≤3 mm treated with tissue adhesive 8
• Mean healing time is approximately 33-34 days when successful 2
• Visual acuity improves in 71-78% of successfully treated cases 2

Morphological and Functional Outcomes

• Success correlates significantly with patient age, number of glue applications required, and presence of complications 8
• Infective keratitis is the major cause of corneal perforations requiring tissue adhesive 8
• The adhesive facilitates non-emergent repair of central defects, allowing for better surgical planning 1