RELATIVE STRENGTH OF SCLERAL TUNNEL INCISIONS WITH INTERNAL CORNEAL LIPS CONSTRUCTED IN CADAVER EYES

We constructed scleral tunnel wounds with internal corneal lips and su tureless closures in ten cadaver eyes without previous intraocular sur gery. Each wound differed in width, total incision length, and interna l corneal lip size. At a low and high range of initial intraocular pre ssure (IOP, 10 to 15 mm Hg or 20 to 25 mm Hg), we compared the wounds' resistance to leakage during application of external pressure. A squa re wound with a 4.0 mm width and 4.0 mm overall length, including a 1. 5 mm corneal lip, had the optimum wound dimensions. These produced a s table incision that resisted leakage at external pressures up to 525 p ounds per square inch equally well at both IOP ranges. Leakage occurre d at lower external pressures for wounds with greater width, smaller c orneal lips, or wound widths that were greater than wound lengths; suc h wounds were also more prone to leakage at the low IOP range. When co nstructed properly and adequately, the 4.0 mm wide scleral tunnel inci sion with 1.5 mm internal corneal lip is a strong and safe wound for s utureless cataract surgery.