Comparison of conjunctival pedicle flap to corneal adhesion achieved by Tisseel® fibrin glue, ethyl cyanoacrylate adhesive, ReSure® hydrogel sealant, and conventional suturing with 8-0 VICRYL® suture

Background: Conjunctival pedicle flaps are one of the most frequently employed surgical interventions used to address a variety of sight threatening corneal diseases in veterinary ophthalmic practice. Securing the conjunctiva to the cornea is typically achieved through suturing, which is technically challenging and can result in prolonged surgical times, increased corneal edema, increased scar tissue, foreign body reaction, suture abscess and dehiscence. In human ophthalmology, a number of sutureless techniques to affix ocular tissues are being explored. Specifically, these approaches include synthetic tissue adhesives, bioadhesives, and hydrogel sealants. The proposed advantages of adhesives over suture, include reduced operative times, watertight seals, decreased foreign-body sensation and inflammation, faster healing times and tissue regeneration with original architecture restoration. Objective. To evaluate the maximum tensile force a conjunctival pedicle flap is able to withstand with respect to different fixation methods, i.e., Tisseel® fibrin glue, ethyl cyanoacrylate adhesive, ReSure® hydrogel sealant, or 8-0 VICRYL suture. Animals Studied. Ex-vivo porcine globes Procedures. Following a 500-micron restricted depth lamellar keratectomy, conjunctival pedicle flaps were dissected and secured to corneal defects with either the bioadhesive Tisseel®, or the synthetic adhesives ReSure®, ethyl cyanoacrylate, or 8-0 VICRYL® suture. Harvested corneoconjunctival flap interfaces were clamped to an accelerometer and potentiometer device, and loaded under video surveillance until the point of failure. Peak load at failure was determined for each test and used to compare between sample types. Results. 40 flaps underwent tensile force testing, with 6 being omitted for dehiscence prior to tensile testing. Of the 34 tests included in analysis, 10 conjunctival flaps were secured with suture, 10 with cyanoacrylate, 8 with ReSure® hydrogel sealant, and 6 with Tisseel® fibrin glue. A significant increase in maximum withstood tensile force was recorded between sutured flap fixation when compared with cyanoacrylate glue (p=0.02474), ReSure® hydrogel sealant (p= 0.00000), and Tisseel® fibrin glue (p= 0.00002). Cyanoacrylate fixation was significantly stronger when compared with ReSure® hydrogel sealant and Tisseel fibrin glue (p=0.01194 and 0.01798 respectively). There was no significant difference in adhesion strength between ReSure® hydrogel sealant and Tisseel® fibrin glue (p=0.95675). Conclusions. Conjunctival pedicle flap fixation using 8-0 VICRYL® suture fixation was able to withstand significantly greater maximum tensile force application in comparison with the ReSure®, Tisseel®, or cyanoacrylate adhesives.