Preclinical Investigation of Ab Interno Goniotomy Using Three Different Techniques

PURPOSE: To evaluate incisional or excisional tissue-level effects of ab interno goniotomy techniques on human trabecular meshwork (TM). METHODS: The TM from human cadaveric corneal rim tissue was treated using three devices: (1) Kahook Dual Blade (KDB) GLIDE, (2) iAccess, and (3) SION. Two human corneal rims were used for each of the iAccess and SION devices and one with the KDB GLIDE, with 360 degrees of TM treated in each case. Sections were then prepared for analysis and comparison between devices. Tissue samples underwent standard histologic processing with H&E stain, followed by comparative analyses. RESULTS: Areas treated with the KDB GLIDE device resulted in nearly complete excision of TM overlying the canal of Schlemm without injury to surrounding tissues. The iAccess device can be used as a focal trephine to create holes or dragged for TM disruption. When used to create holes, iAccess punched through the full thickness of the TM and also disrupted the anterior scleral tissue. It caused some incisional openings through the TM but with significant leaflets remaining and minimal true “hole-punch” effect. When the device tip was dragged, iAccess incised the TM and left debris behind with little, if any, excision of tissue. SION led to both incision and excision of TM with incision predominating over excision. CONCLUSION: The various methods evaluated to perform ab interno goniotomy resulted in varying degrees of TM incision or excision. Only the KDB GLIDE device resulted in reliable excision of TM, while the other devices produced incision or minimal excision of tissue with residual leaflets and debris. Use of iAccess resulted in focal disruption of the anterior scleral wall. Because incisional approaches that leave longer residual leaflets may be more prone to fibrosis and closure compared to excisional treatments, clinical correlation will be necessary to better understand the significance of these findings with respect to relative effectiveness of intraocular pressure lowering in eyes with glaucoma.